Posted August 18, 2011

       

In Celebration of Psalm Nineteen:
"God's handiwork in Creation

Body Plans:
Beginnings of the Eukaryotic Phyla

ca. 600 Ma

"...a great plan, having its original in the Divine Mind, which has gradually fitted the earth to be the habitation of intelligent beings, and has introduced upon the stage of time organism after organism, rising in dignity, until all have found their completion in the human nature, which, in its turn, is a prophecy of the spiritual and Divine."
Hugh Miller, Sketch-book of Popular Geology (4th  Ed, 1869)
preface by Lydia Miller

The presence of fossils in the geologic formations gives a chronological account of when the first examples of each phylum appeared. Of course the account only gives a latest date, because an earlier origin may have occurred without leaving fossil evidence -- at least evidence that has been discovered to date.

This page gives the earliest fossil examples of the Eukaryotic phyla using the nomenclature of Lynn Margulis in Kingdoms and Domains, 4th Edition (2009). As has been noted elsewhere, Margulis divides eukaryotic life into four kingdoms:

• Kingdom Protoctista, the single-celled eukaryotes,

• Kingdom Animalia, the multi-celled animal eukaryotes, and

• Kingdom Plantae, the multi-celled plant eukaryotes, and

• Kingdom Fungi, the eukaryotic fungi.



Plants and Animals.

"The Animal kingdom, one in system from the beginning."
Dana, Manual of Geology,  p. 1029

The Difference between Plants and Animals. It is clear that the familiar world of visible life divides into fungi, plants and animals. Leaving aside the fungi, the question of what distinguishes a plant from an animal is surprisingly complex -- or at least it requires the use of a surprising array of esoteric technical considerations. At the level of single-celled creatures -- the protists -- the distinction seems almost arbitrary: Are diatoms plants and rotifers animals? Margulis avoids this by defining plants and animal kingdoms to be multicellular. Still, one might think that for the familiar world of the living, it should be easy to see the distinction. It is not.

Naively, plants are fixed in place and animals move around. But that is not a satisfactory distinction: some animals such as the hydras, sponges, and other ocean bttom dwellers -- not to mention barnacles and the like -- spend most of their lives fixed in place. Again, naively, plants do photosynthesis but animals do not. But not all plants photosynthesize!


The Difference between Plants and Animals

What is a plant and what is an animal? The answer is not easy. From one viewpoint, this difficulty borders on the absurd: everyone knows the difference. But the problem lies in the borderline cases -- in the lower plants and animals. The question arises in the study of fossils: is this fossil an animal or a plant? It is an interesting fact that the 19th century geologists generally did not try to make the distinction -- or perhaps they assumed that the distinction is obvious1.

As obvious as the distinction between plants and animals may seem in daily life, the modern systematists use surprisingly non-intuitive ways to make the distinction. Lynn Margullis, for example, distinguishes between the Plant kingdom (Plantae) and the Animal kingdom (Animalia) based on the nature of the sperm, egg and embryo at fertilization: in plants the embryo is contained in a multicellular ovule at fertilization; in animals, fertilization produces a single-celled zygote, which then forms a multicellular blastula through cell clevage (mitosis). For Margulis, both plants and animals are multi-cellular by definition -- with all single-celled eukaryotes placed into the kingdom Protoctista -- a reasonable move because they never form multi-celled species, although they may form "colonies" that behave as if they were multicellular creatures1.1.

Plants - Zygotic/Sporic Meiosis
Animals - Gametic Meiosis
Zygotic/Sporic Meiosis
Haploid cells duplicate after meiosis and prior to fertilization, which occurs within a multi-celled ovule containing the egg. The ovule includes nutrients for initial growth.
Gametic Meiosis
Haploid cells fertilize without duplicating, forming a zygote which then divides by mitosis to form a blastula. The (larger) egg includes nutrients for the initial cell division.
Figure 1.1
Plant and Animal Fertilization and initial growth

While this distinction between plants and animals may be technically accurate, it does not seem to get at the essence of plants and animals. It is difficult to see why this difference should lead to the vast difference between plants and animals; it seems more an accidental attribute than an essential one.

There are two obvious differences between plants and animals. First, plants do not appear as elaborately organized as animals. Tree branches seem to be somewhat randomly designed, perhaps subject to growth rules, but allowing a broad range of variation within those rules. Animals also have some variation, but an animal body conforms to a much more detailed specification that seems to be determined by placement within an overall body design. We can summarize this difference by referring to plants as algorithmically designed, and to animals as
topologically designed.

See also
Algorithmic and Topological Body Plans



The Earliest Fossils of the Protist Phyla2

Margulis places all single-celled eukaryotes in the kingdom Protoctista, the Protists, which avoids discussion of whether they are plants or animals -- and leads to a clean definition of the plant and animal kingdoms at the embryonic level. Thus, for example, some classification schemes place diatoms (Pr-18) in the Plant kingdom, and place Forams (Pr-3) and Radiolaria (Pr-31) in the Animal Kingdom.

Many Protist (single-celled eukaryotes) phyla are absent in the fossil record, because many are soft-bodied and don't readily fossilize. Exceptions include occasional species (such as the Foraminifera, Pr-3 and Radiolaria, Pr-31) that have skeletons, shells or other hard parts (spicules), and colonies (algal mats, etc.) -- especially when (as in bacterial stromatolyte colonies) they entrap or excrete minerals (calcium, silica, etc.).

The known examples represented in the fossil record are (Using the nomenclature of Margulis):

PR-3 - Granuloreticulosa (Foraminifera).   Forams first appeared in the early Cambrian era, about 542 Ma. They secete a mucilage that c
ements together tiny particles gathered from the sea floor into an agglutinated shell. All species are benthic (bottom-dwelling); however some species moved about on the sea floor while others are stationary either by attaching themselves to the bottom or by burrowing into it.  Forams are a commonly found in core samples as agglutinated tubes 3-4 cm (1-1.5") in length
2.1.

Cambrian Foraminifera
Figure 2.1
Foraminifera
Platysolenites antiquissimus
Cambrian Era (445 Ma)
Upper - cross-section (squashed)
Lower - typical agglutinated tubular form

For images of recent foraminifera, see the H.M.S. Challenger reports: Henry Bowman Brady, Report on the Foraminifera (1884); and W. B. Carpenter, Report on the Orbitolites. (1883).

Pr-04 - Xenophyophora "No proven fossil record" [Margulis p. 143]

Pr-05 - Dinomastigota "Significant fossil record from base of Cambrian"  [Margulis] The dinoflagellates are notable because their internal structure is quite peculiar. The chromosomes are formed in a unique way, and mitosis is also peculiar, leading some to speculate that they are half-way between bacteria and eukaryotes
02.2. This peculiar structure implies ancient roots, and indeed dinoflagellates appear throughout the geological record, from the cambrian to the present with strong likelihood that their pedigree may include some precambrian fossils.

dinoflagellate
Figure 2.2
Dinoflagellates

Pr-18 - Bacillariophyta. This is the phylum that includes the diatoms. Since Margulis classifies all single-celled eukaryotes as protists, the diatoms are not classified as plants (as other naming schemes do), even though they conduct photosynthesis. Diatoms are plankton that can be found in floating algal mats. The name refers to the two-part silicon skeleton.

Diatoms have two useful functions: they fix carbon through photosynthesis, and they remove silicic acid from the oceans. In both of these functions, they play a major role. The silicon deposits on the cell wall to form skeletons of amorphous silicon dioixide
(SiO2) in beautiful and fantastic shapes which are a favorite object to view under a SEM microscope (Figure 2.3).  The details of how diatoms remove silicon from the water are not yet well-understood, but it is thought that the diatom interiors manage to maintain dissolved silicon in a supersaturated condition by an unknown process, which then precipitates the silicon on the cell walls to form the skeletons
02.3.


Lower Cretaceous Diatoms diatoms
Figure 2.3a
Lower Cretaceous Diatoms
From Core Samples, Weddell Sea (Antartica)
 Evolution of the Diatoms (2006)
Sims, et al., Figs. 11-16
Figure 2.3b
Modern Diatom skeletons

Major diatom deposits date from the Cretaceous era (144-65 Ma) -- forming extensive beds of diatomaceous earth. Diatoms could well originate at a much earlier date, but the
silicon crystallizes under pressure, so early examples may not have survived deep burial -- see Sims, et. al.

For images of recent diatoms, see the H.M.S. Challenger report by Conte Abate Francesco Castracane degli Antelminelli, Report on the Diatomaceae (1886).


Pr-25 - Hapatomonada.  Single-celled golden-brown algae. The algae have two forms during their life cycle: the "resting state"
Coccolithophores with disc-like coccoliths (Calcium Carbonate "scales of renown to paleontologists" which had a major part in creating the world's chalk deposits), and the mobile haptomonad with a single whip-like undulipod (often mis-named a flagellum). The coccoliths are detailed and very distinctive and changes over time make them good markers of geologic time. Coccoliths have been reported in Devonian deposits in China (ca 360 Ma). These are apparently the oldest examples; until this discovery, the earliest fossils came from the Triassic Era (250-200 Ma)
02.4.


Triassic Coccolith
Figure 2.4
Coccolith
Left: Modern -- Wiki
Right: Early Triassic (??) (250 Ma)

Pr-28 - Chlorophyta (green algae).

Pr-31 - Actinopoda (Radiolaria). The radiolaria are protists that produce mineral skeletons and spicules (rods). Among the many families the skeletons are formed of various minerals -- silica (SiO2) or opal (hydrated silica - SiO2•nH2O), and strontium sulfate. The skeletons exhibit a fantastic variety of detailed and elaborate forms -- for stunning drawings of radiolaria from the HMS Challenger Expedition, see Ernst Haeckel, Report on the Radiolaria (1887)
02.5. One remarkable feature is that the microtubule spicules (at least in some species) appear to be used as oars may be "found rowing in the Mediterranean with the splendor of a Roman galley." [Margulis, p. 207].

Radiolaria fossils have been discovered in China from the lower Cambrian (545 Ma) -- See Figure 2.5, with many others from the Ordovician and later
02.6.

Early Cambrian Radiolarian
Figure 2.5
Lower Cambrian Radiolarian (545 Ma)
Yangtze Platform, China

For images of recent radiolaria, see the H.M.S. Challenger report by Ernst Haeckel, Report on the Radiolaria, (1887).


Pr-32 - Gamophyta (green algae). green Algae secrete calcium carbonate which assists in fossilization. The fossil record begins in the Cambrian Era, although it is possible that they may have existed prior to that time -- since the body plan is somewhat indefinite, it is hard to classify some earlier candidates with confidence.


Margaretia-dorus green algae
Figure 2.6
Middle Cambrian Green Algae
Margaretia dorus
Wheeler Shale, Millard County, Utah
The Virtual Fossil Museum

Cambrian-GreenAlgae Yuknessia
Figure 2.7
Middle Cambrian Green Algae
Yuknessia
non-mineralized fossil
Huaqiao Formation, China

Pr-33 - Rhodophyta (red algae). 
"Unicellular rhodophytes, of which there are a few living today, may go back well into the Precambrian, but since none of the Precambrian fossils in question contain pigments, they cannot be identified confidently as red algae. Multicellular rhodophytes were present in the late Precambrian; the oldest may be as old as 1.25 billion years... Because of their ability to secrete calcium carbonate, calcareous red algae have a better Phanerozoic fossil record than many other groups of algal protists... Most limestone deposits of reef origin consist largely of the skeletons of coralline algae, and because these are often associated with petroleum deposits, there has been a great deal of attention focussed on these fossils. Despite this attention, we still do not fully understand how the rhodophytes precipitate calcium carbonate; the mechanism is not as well studied as those in bone and shell deposition. " -- Rhodophyta: Fossil Record.


The Cambrian Fossil Record and the Origin of the Phyla


The Animal Phyla: First Appearances in the Fossil Record03 
"The Lower Cambrian species have not the simplicity of structure that would naturally be looked for in the earliest Paleozoic life. They are perfect of their kind and highly specialized  structures. No steps from simple kinds leading up to them have been discovered; no line from Protozoans up to Corals, Echinoderms, or Worms, or from either of these groups up to Brachiopods, Mollusks, Trilobites, or other Crustaceans. This appearance of abruptness in the introduction of Cambrian life is one of the striking facts made known by geology."

The known examples represented in the fossil record are (Using the nomenclature of Margulis):


A-3 Phylum Porifera (Spongia). Early Cambrian fossils include a short-lived (about 10My) but prolific blossoming of a sponge Archaeocyathans. They are the first are reef-building animals, conical shaped with a calcium carbonate (calcite) shell -- similar in overall shape to the later rugose corals. Because of their brief span they are an index fossil for the lower Cambrian.

Cambrian Sponge archeocyathid
Figure 3.1
Lower Cambrian archeocyathid

Sponges commonly have needle-like spicules which they use for movement and defense. The following figure shows a number of Cambrian sponges with spicules.



Cambrian Sponges0
Figure 3.2
Cambrian sponge Choiacarteri
Burgess Shale


The following Mid-Cambrian fossil sponges are listed by Charles Walcott
03.1. Note the surface pores of the sponges indicated in the figures.

Walcott-sponge-p002-02
Figure 3.3a
Mid-Cambrian Sponge Leptomitus zitteli.
Georgia Formation, Parker's Quarry, Vermont
Middle Cambrian Hyalouema
showing silicious spicules. natural size.
Walcott, Cambrian Faunas, plate 2
Walcott-sponge-p004-01
Figure 3.3b
Mid-Cambrian Sponge
Ethmophyllum Whitneyi
Silver Peak, Nevada.
Note the pores in the magnified section.
Walcott, Cambrian Faunas, plate 4
Walcott-sponge-p005-01
Figure 3.3c
Mid-Cambrian Sponge
Ethmophyllum rensselaericum
Georgia Formation, Troy, NY length 0.3"
Note the pores in the magnified section.
Walcott, Cambrian Faunas, plate 5

For images of recent sponges, see the H.M.S. Challenger reports:

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Porifera
Report
Author
Year
Hexactinellida: Part LIII F. E. Schulze
1887
Tetractinellida: Part LXIII W. J. Sollas,
1888
Monaxonida: Part LIX Stuart O. Ridley
1887
Keratosa: Part XXXI N. Poléjaeff
1884
Deep-Sea Keratosa: Part LXXXII Ernst Haeckel
1889


A-4 Phylum Coelenterata (Cnidaria). All Coelenterates have stingers called cnidaria; hence this is an alternative name for the phylum.  The phylum includes hydras, medusas, jellyfish and corals. Often the life-cycle of a species may pass through several of these forms.

Middle Cambrian Microfossils
Late Cambrian Macrofossils
Cambrian Narcomedusa Cambrian medusa
Figure 3.4a
Medusa -- Narcomedusa
Marjum Formation (Utah)
fossils up to 8mm across.
(bar = 2mm (??))
Figure 3.4b
Medusas -- Scypohzoa
Krukowski Quarry, Mosinee, Wisconsin
(Individual medusas up to 2 ft. diameter)
Note water ripple marks


Cambrian Coral
Figure 3.5
Middle Cambrian Coral
Conasauga Shale, Cherokee County, AL

The Cnidaria are unique among the animal phyla in the presence of their namesake stingers (cnidaria). These stingers are remarkable examples of exquisite design and engineering -- see the box on Cnidaria.

For images of recent Coelenterata, see the H.M.S. Challenger reports:

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Coelenterata
Report
Author
Year
Siphonophoræ: Part LXXVII Ernst Haeckel
1888
Deep-Sea Medusæ: Part XII Ernst Haeckel 1882
Hydroida: Part XX, LXX G.J. Allman
1883
Corals: Part VII H. N. Moseley
1881
Reef Corals: Part XLVI John J. Quelch 1886
Actiniaria: Parts XV, LXXIII Richard Hertwig
1882,
1888
Pennatulida: Part II Albert V. Kölliker
1880
Calcarea: Part XXIV N. Poléjaeff
1883

A-5 Ctenophora. Comb jellies. Ediacaran (Australia) fossil beds show abundant remains of an early animal named
Funisia dorothea (Figure 3.6) viewed by some as a comb jelly, and by others as a kind of sponge. Consistent with the view that they are early comb jellies is the view of one line of research (based on cladistic studies of gene structure) that the comb jelly was the earliest form of complex life, earlier than the sponge. Thus "the relatively complex comb jelly at the base of the tree of life suggests that the first animal was probably more complex than previously believed."03.2

The earliest known Ctenophore (if Funisia is classified as a sponge) is an embryonic comb jelly of the lower Cambrian03.3.

Ediacaran-Funisia Comb Jelly?
Figure 3.6
Funisia
Ediacaran (600 Ma)
Early Comb Jelly?


A-6 Gnathostomulida.
Early Cambrian "protoconodonts" are currently believed to be the unrelated remains of chaetognaths (or "arrow worms"). Margulis classifies Conodonts in Phylum A-37 (Craniata).

A-7 to A-19 are mostly soft-bodied and many are worms
.

A-11 Nematoda.
(Nematodes).


Cambrian Nematode
Figure 3.7
Nematode (horsehair worm)
Lower Cambrian  (~525 Ma)
Cricocosmia jinningensis
Chengjiang Formation, China
Note intestine (darkened area).

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Nemertina (A-10)



A-12 Nematomorpha
(horsehair worms). A lower Cambrian worm of phylum Nematomorpha, in quite remarkable preservation, was discovered in 1999 in the Chengjiang Maotianshan Shales of China (Figure 3.8).

Lower Cambrian Maotianshania-cylindrica, Chengjiang
Figure 3.8
Early Cambrian Nematomorph worm
Maotianshania cylindrica


A-20 Phylum Chelicerata
. The Chelicerates include horseshoe crabs, scorpions, spiders and mites. Some classification systems combine chelicerata with crustaceans and mandibulata into a single arthropod phylum [Margulis, p. 294]. The shells are somewhat soft and may not fossilize well.

The Cambrian fossils that are classified as Chelicerates lack the Chelicera (front pair of clawed, jointed "legs")03.4-- but otherwise appear to be the proper form.

The oldest horseshoe Crab fossil comes from the Ordovician Era, about 445 Ma (Figure 3.9).

Oldest Horseshoe Crab
Figure 3.9
Oldest Fossil Horseshoe Crab
Ordovician Era (445 Ma)
Left: Fossil; Right: Modern


Extinct Phylum Trilobita. The Trilobite is perhaps the most remarkable Cambrian fossil. It appeared suddenly as a fully formed arthropod, and lasted for over 200 My, becoming extinct in the Permian Extinction (about 250 Ma). Trilobite fossils represent the earliest clearly defined occurrence of compound eyes. In most classification schemes the trilobite is placed in its own phylum because of its unique body structure which consists of multiple segments each with three lobes (left to right). The only comparable animal is a newly-hatched trilobite larva of the horseshoe crab (a Chelicerate), so-named because its body plan resembles a trilobite. The Cambrian trilobites are mostly small, but in later times some fossils are quite large -- up to 28 inches. See Chapter 9 for further remarks on the trilobite, particularly the trilobite eyes.


trilobite Early Cambrian
Figure 3.10
Early Cambrian Trilobite

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Arthropoda (Chelicerata and Mandibulata)

Pelagic Hemiptera: Part XIX
Pycnogonida: Part X
Brachyura: Part XLIX
Anomura: Part XLIX
Macrura: Part LII
Schizopoda: Part XXXVII
Stomatopoda: Part XLV
Cumacea: Part LV
Phyllocarida: Part LVI
Isopoda: Parts XXXIII, XLVIII
Amphipoda: Part LXVII
Cirripedia: Parts XXV, XXVIII
Copepoda: Part XXIII
Ostracoda: Part III

A-21 Phylum Mandibulata. This phylum includes the classes Hexapoda (Insecta) -- insects and spiders, Crustacea -- crabs, shrimp and lobsters, and Myriapoda -- centipedes and millipedes.

Cambrian Crustacean Phosphatocopid
Figure 3.11
Cambrian Crustacean Phosphatocopid
with preserved body parts03.5
SEM photograph

A-22 Phylum Annelida
.  segmented worms -- Earthworms, etc.

Spriggina is a possible pre-Cambrian annelid. It is a segmented worm about 3 cm in length. It appears to be armored with interlocking plates. There are no Cambrian examples.


Cambrian Spriggina Annelid? (WIKI)
Figure 3.12
Ediacaran (pre-Cambrian) Annelid?
Spriggina

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Annelida:

Annelida: Part XXXIV

A-26 Phylum Mollusca. A Cambrian fossil Mollusc (class Monoplacophora) is named Knightoconus. This was thought to be extinct, until ten living species were discovered in 1952. Since that time a number of other specimens have been found. Modern species live on the ocean bed in deep water. "All extant classes of molluscs, except Scaphopoda, began at various times during the Cambrian."03.6


Cambrian Mollusc Class Monoplacophora
Figure 3.13
Cambrian Mollusc
 Class Monoplacophora.  Knightoconus
top: fossil; bottom: living representation

Cambrian Mollusc Class Monoplacophora
Figure 3.14
Cambrian Gastropod Mollusc
A. attleborensis
a snail, Class Gastropoda
Aldanella ex.gr. attleborensis (Shaler & Foerste, 1888).

Cambrian Mollusc bivalve
Figure 3.15
Cambrian Bivalve Mollusc
 Phosphatocopina Müller, 1964 (Larva)
SEM micrograph, Oblique view.
Original size up to 5mm.
D. Walossek, Ulm03.7

Cambrian Molluscs
Figure 3.15a
Cambrian Molluscs
Dana, Manual of Geology p.472
   

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Mollusca

Brachiopoda: Part I
Polyzoa: Parts XXX, L, LXXIX
Cephalodiscus: Part LXII
Phoronis: Part LXXV
Cephalopoda: Part XLIV
Pteropoda: Parts LVIII, LXV, LXVI
Nudibranchiata: Part XXVI
Marseniadæ: Part XLI
Heteropoda: Part LXXII
Scaphopoda & Gasteropoda: Part XLII
Polyplacophora: Part XLIII
Lamellibranchiata: Part XXXV
Anatomy of Deep-Sea Mollusca: Part LXXIV

A-27 Phylum Tardigrada
Tardigrades are microscopic animals that range from 100 µm to 1,500 µ
m in size

Cambrian Tardigrade 530 Ma
Figure 3.16a
Cambrian Tardigrade (530 Ma)
Orsten Formation
Modern Tardigrade
Figure 3.16b
Modern Tardigrade


A-28 Phylum Onychophora. This phylum includes the lobopods or velvet worms. Lobopods are segmented and typically bear legs with hooked claws on their ends.

Cambrian-Lobopod
Figure 3.17
Lobopod -- Microdictyon sinicum
Chengjiang, China
Lower Cambrian
Length: 7.7 cm.

A-29 Phylum Bryozoa. Bryozoans are sometimes called "moss animals". Individuals are small and tubular in shape with a looped digestive tract so that the mouth and anus are both located at one end. The individuals usually live in colonies.  Until recently, this phylum was thought to begin in the Ordivician Era; however, in 2010, a Cambrian bryozoan was reported03.8.


  Ediacaran-Funisia Comb Jelly?
Figure 3.18
Bryozoa - Hallopora
Ordovician (North America)


A-30 Phylum Brachiopoda. The following Mid-Cambrian shellfish are listed by Charles Walcott in his book CambrianFaunas (1886). Numerous fossils of this sort have been found (Figure 3.19).


Walcott-Brachyopod-p007-01
Figure 3.19a Brachiopoda
Lingulella caelata, 2x
Middle Cambrian, Georgia Formation
ridge East of Troy, NY
Walcott, Cambrian Faunas, plate7
Walcott-Brachyopod-p008-01
Figure 3.19b Brachyopoda
Acrotreta gemma, 3x
Middle Cambrian
Pioche, Nevada
Walcott, Cambrian Faunas, plate 8
Walcott-Brachyopod-p009-04
Figure 3.19c Brachiopoda
Acrothele subsidua
Middle Cambrian
Antelope Springs, Utah
Walcott, Cambrian Faunas, plate 9



Cambrian Brachiopods
Figure 3.19d
Cambrian Brachiopods
Dana, Manual of Geology p.471


According to Wikipedia, The genus Lingula (Bruguiere, 1797) is "among the oldest known animal genus that has extant species.... Shells of living specimens found today in the waters around Japan are almost identical to ancient Cambrian fossils."

A-33 Phylum Hemichordata. The Hemichordates (acorn worms) are marine worms -- often live planktonic lives as larvae and benthic (ocean floor) lives as adults. The name "half-chordate" is a misnomer [Margulis] since they do not have a notochord.

Cambrian-Hemichordata Yannanozoon lividum
Figure 3.20
Earliest known Hemichordate
Yannanozoon lividum
Chengjiang, China
Lower Cambrian (525 Ma)
Length 2.3 cm.


A-34 Phylum Echinodermata. The Echinoderms include starfish, sea lilies, sea urcins, and sea cucumbers.  Most of these appear later in the Ordovician Era. The sea lilies (Crinoids), or at any rate, crinoid-like fossils, occur in the Cambrian Era. Gogia is the most common example.



Cambrian Gogia Spiralis Crinoid
Figure 3.21
Middle Cambrian Crinoid
Gogia Spiralis  length 5.8 cm
Wheeler Shale, Utah


Cambrian Gogia Parsleyi-blastozoan Echinoderm
Figure 3.22
Middle Cambrian Echinoderm Blastozoan
Gogia Parsleyi
Upper Murero Formation NE Spain

H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Echinodermata:
Holothurioidea: Parts XIII, XXXIX
Echinoidea: Part IX
Ophiuroidea: Part XIV
Asteroidea: Part LI
Crinoidea: Parts XXXII, LX
Myzostomida: Parts XXVII, LXI

A-35 Phylum Urochordata (Tunicata). Urochords are the only animals that can produce cellulose [See note 1.3].
 
 

Cambrian-Tunicate Shankouclava shankouense
Figure 3.23
Lower Cambrian Tunicate
Shankouclava
Maotianshan Shale, China03.9
Right: Reconstruction.


H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Tunicata
Report
Author
Year
Tunicata: Part XVII
William A. Herdman
1882
Tunicata: Part  XXXVIII William A. Herdman 1886
Tunicata: Part LXXVI William A. Herdman 1888

A-36 Phylum Cephalachordata.

Cambrian - Pikaia a "pre-vertebrate cephalochordate from the Cambrian Burgess Shale"

 Carbonaceous-Foliage
Figure 3.23a
Pikaia


A-37 Phylum Craniata.
The craniates have a central, hollow, fluid-filled nerve cord ending in a brain that is enclosed in a cranium (brain-case). In the embryo, all craniates have a flexible rod called a notochord, which in vertebrates is replaced in maturity by a bony or cartilaginous backbone.[Margulis]

The earliest (probable) chordate is Haikouichthys, a 2-3 cm. length fish-like Cambrian fossil from China reported in 1999, with additional fossils reported in 2003 that show well-developed eyes, and other sensory structures characteristic of the cratiates, as well as the muscle blocks typical of early vertebrates
03.10. Bony fish officially date to the Ordovician Era.

Cambrian-Haikouichthys
Figure 3.24
Haikouichthys
Lower Cambrian
Chengjiang China

Conodonts, also classified as Craniates (based on living species) may also date from the mid-Cambrian -- see the box on Conodonts in Chapter 9.


H.M.S. Challenger Expedition (1873-1876) Reports of Species in Phylum Vertibrata (Craniata)

Human Skeletons:   Parts  XXIX, XLVII
Seals: Part LXVIII
Bones of Cetacea: Part IV
Marsupialia: Part XVI
Birds: Part VIII
Anatomy of Petrels: Part XI
Anatomy of Spheniscidæ: Part XVIII
Fishes: Parts VI, LVII, LXXVIII




The Plant Phyla: First Appearances in the Fossil Record


Moving to the Land04

In the move to land, Land dwellers (plants and animals) need to combat:
• Gravity: no longer buoyant
• Cosmic radiation: no longer filtered out by water medium
• Desiccation: no longer surrounded in liquid
• Lack of dissolved oxygen/carbon dioxide: need to process gaseous air
• Lack of water to aid in reproduction
• Lack of dissolved nutrients in surrounding medium: need other ways to get food
• For animals: different senses (sound moves slower and more weakly, pressure and electric senses don't work, air has different refractive index than water, etc.)

Plants (excluding the Protists) are designed specifically to combat these problems.
All plants have three tissue systems:
• A dermal system - an outer protective layer;
• A vascular system - veins that move water into the plant (the Xylem) and move nutrients within the plant and to the roots (the Phloem)
• Ground tissue - the rest of the plant (including food storage, photosynthesis, etc.)
Plants maintain their shape and structure in the face of gravity with one or more of:
Cellulose
Lignin (woody material)
Osmotic pressure to maintain shape.


    Moving to land began seriously about 470 My ago, some 100 My after the Cambrian explosion. By this time corals, mollusks, and other sea creatures were long established. Some early fungi appeared at about 500 My and mosses about 470 My, both in the Ordovician era. The evidence for this is not found in actual plant fossils but in spores which appear at this time, and are markers of plant life (see the box). These early colonizers of the land lack real roots, so they can only be small and can only grow in water or wet surroundings. However, they could move from shorelines to the interior of land masses, provided the necessary bacteria had preceeded them to supply food and nitrogen, and the spores have the ability to go into a dormant state during dry periods.

    Cosmic and solar radiation at this time was still severe, but for these simple plants, that was only an inconvenience, because every plant zapped by radiation became food for other plants. Various means could be used to minimize the effects of radiation, including the use of shelter, damp locations and subterranean growth. As long as plant reproduction could keep ahead of the destruction, they were able to cope.

    The really serious issue was water, more precisely, the retention of water in the plants that were exposed to dry land and air. By the start of the Silurian age, 430 My ago, the algae and mosses appear with waxy coats that prevent drying out, and stomata which controlled the plant respiration and moisture content.  From this time plants spread all over the dry land. The waxy coating and stomata are characteristic of all land plants from this time on.
   
    Unlike the animal phyla, the various plant phyla appear on earth over a long period of time, with the crowning achievement, the flowering plants, first appearing in the fossil record around 145 Ma. There is a clear reason for this: all animals first arose in the oceans; plants live in (or near to) the atmosphere -- that is, on dry land or adjacent shallow water. Although permanent dry land first appeared around 2 Ga, as a result of plate tectonics, hard cosmic and solar radiation sterilized it. This condition continued until the oxygen in the atmosphere could build up an adequate outer-atmosphere ozone layer. Only microbes and simple plants and animals with high reproduction rates could survive the race against destruction by radiation. Once that ozone layer built up, dry land was open to colonization.

When the flowering plants arrived, the colonization by animals took place in parallel. There was a close symbiosis between the development of new plant types and animal types  -- particularly the insects -- that need each other for food and fertilization.


Fossil Record of Plant Development
See also Plant Innovations

See Wiki article, Evolutionary history of plants

Phylum
Innovation
Date (Ma) of earliest fossils

Cyanobacteria (B-6) photosynthesis
nitrogen fixing
heterocysts
atp synthesis (energy storage)
sucrose cycle (Calvin cycle)
proton pump
spores (akinetes)
Spores protect the living cell by surrounding the cell with a thick wall that can resist dessication, heat, and even the vacuum of space for prolonged periods of time.
3,500 Ma


The first fossil living species were already colonial -- witness the cyanobacterial chains and the stromatolyte formations. Cells in a colony differentiated their tasks -- for example, nitrogen fixing heterocysts had to be specialized because fixing is poisoned by the oxygen byproduct of normal cell metabolism. After the invention of the eukaryotic cell, multicellular plants and animals arose. Multicellularity is caused by a delay in the process of cell separation after division.



Eukaryotic Cells
~1,500 Ma



First Multicellular Plants and Animals
~600 Ma?? (Ediacara)


Kingdom Fungi Not considered part of the plant kingdom by Lynn Margulis."fungi are clearly more closely related to animals than to lants, considering that chitin is the main component of both fungal cell walls and the arthropod exoskeleton. Plant cell walls instead contain cellulose."[Margulis p. 382].
~500 Ma (Ordovician)


Kingdom Protoctista
single-celled eukaryotes
Algae, seaweeds slime-molds. Do not develop from an embryo as in plants; therefore, not considered part of the plant kingdom by Lynn Margulis. Many are mobile with undulipodia (a special kind of flagella or cilia) during part of their life cycle.[Margulis, p. 120]
~540 Ma (Cambrian)


The earliest animals appear in the fossil record before the earliest fungi and plants. A possible reason is that the early animals all developed in water environments, protected from harmful cosmic rays. Plants and fungi are basically land-based, and so could not fully develop until the cosmic rays were at least partly mitigated by the ozone layer.




Migration to Land
~470 Ma.


Migration to land faced a number of problems:
Cosmic Radiation. The atmosphere's ozone layer protects land plants and animals from most high energy cosmic and solar rays. It first became effective around 400 Ma. Some early fungi appeared at as early as 500 Ma and mosses about 470 Ma, both in the Ordovician era. Cosmic and solar radiation at this time was still severe, but for these simple plants, that was only an inconvenience, because every plant zapped by radiation became food for other plants. As long as the plants could find some shelter from direct rays (overhangs, soil, depressions, water) and their reproduction could keep ahead of the destruction, they were able to cope.
Dessication. A more serious problem for migration to dry land was the need for water. This limited the earliest land plants to moist environments.
Structural Support. A water environment provides  considerable support for weighty bodies, but when plants grew into the atmosphere, they had to support their own weight. Thus early land plants were limited to low-rising masses.




Vascular Plants.
~450 Ma


Club Mosses,
Lycopods  (PL-4)
At one time were very prolific -- heights to 40m in the carboniferous age (350-290 Ma). No true root -- grow from rhizomes as do some of the non-vascular plants  (mosses, etc.)
400 Ma. Carboniferous


Horsetails (PL-6)
Prolific in carboniferous age  -- heights to 15m.



Ferns (PL-7)
Prolific in carboniferous age  -- heights to 25m. Require moist environment for fertilization.




dessication resistance This innovation was needed before plants could thrive in a dry atmosphere. Major innovations involved:
     • Pollen Tube. This allows fertilization in a dry environment [Margulis, p. 419]. From the Gincko (Pl-9) and later.
     • Leaves (flat areas for chlorophyll) originated in the Devonian Era (around 400 Ma).
     • Cutin -- a waxy layer to retain moisture in all plant surfaces that exist in an air environment (such as leaves and stems); and
     • Stomata -- pores in the leaves that can open or close to control respiration.
"Leaves did not become widespread in fossil floras until 50 million years after the emergence of vascular plants." ref (Devonian around 400 Ma)




Early Seed Plants (Lyginopterids) in Devonian.
The earliest-known seeds date back 365 million years ago

380 Ma


During the late Devonian (390-365 Ma) there was massive diversification of plants and the creation of many new species. However this levelled and eventually started to decline at about 360 Ma at the same time as there ware major animal extinctions. During this time, there were significant "improvements" evolving in plants.  ... True leaves first appear in the fossil record in the mid to late Devonian (390-354 Ma) and belong to one of two groups, the microphylls and megaphylls which are both seen in the modern flora. By the middle of the Devonian Period most of the features recognised in plants today are present, including roots, leaves and secondary wood, and by late Devonian times seeds had evolved04.1



cell wall/woody structures




gametes/sexual reproduction




gymnosperms



Flowering Plants (Anthophyta -- PL-12)
angiosperms (flowering plants) (Co-evolved with Bees)
 -- the angiosperm seed "The greatest of all evolutionary innovations"[Margulis, p. 457].
NOTE: The Cretaceous era extends from 145.5 ± 4 to 65.5 ± 0.3 million year. It is characterised by chalky formations. The genesis of the Flowering Plants coincides with this era.
140 Ma (pollen grains)


-- family Garamineae or Poaceae
grasses (Graminoids)
    included bamboos (grow from bottom???)
First appear during the Eocene, around 50Ma. From this time onward, many modern species appear in the fossil record.

• Grow from stem up (unlike most other plants which grow from the tips)
50 Ma




Plant Kingdom
Figure 4.1
The Plant Kingdom Phyla
From Margullis, Kingdoms & Domains p.412
   
For following table see:
Mansfield State (Ohio) Evolution of Plants.


Formation
Timespan (Ma)
Plant Fossil evidence (Compare with Timeline of Plant Evolution)
Innovations
Cambrian
542 to 488.3
algae (protists), but no evidence of fossil plants

Ordovician
488.3 to 443.7
Disputed evidence of  mosses (Phylum Pl-1)04.2

tetrad spores

Silurian
443.7 to 416.0
Rhyniophyta (an extinct phylum)04.3. First vascular plants: Cooksonia, Psilophyton,  Disputed evidence of Lycopod (Pl-4 Baragwanathia).
vascula?
leaves?
somata?
rhizome?
Devonian
416 to359.2
Rhyniophyta (Rhynia Chert) Lignin
cellulose



Plant timeline (media-2.web.britannica.com)
Figure 4.2



The Plant Phyla in the Fossil Record
Description and First Appearances of the Plant Phyla

"The evolution of the first land plants was a major event in the history of Earth. It cleared the way for the irresistible development of animal life on the land."

Spores.  Spores provide the earliest evidence of plant life in the fossil record.  Terrestrial plants produce extremely resistent spores and pollen which are easily transported by wind and water. Trilete spores which are unique to plants,  appear in the MId-Ordovician Age (~470 Ma), and are taken as the earliest evidence of life on land [Wiki]. These spores are produced during sexual reproduction (meiosis) whereby the mother (diploid) cell divides to form 4 haploid cells04.4.


These spore indications of plant life preceed actual plant fossils by 50 My
.  See the box on spores and seeds. Figure 4.3a shows trilete spores and Figure 4.3b shows a fossil (!) spore capsule ejecting sperm cells. Both of these figures come from the Rhynie Chert (early Devonian).

Devonian-SporeTetrad.gif Devonian-Spores.jpg
Figure 4.3a
Spore Tetrads
Rhynie Chert
Lower Devonian
Figure 4.3b
Archegonium ejecting sperm cells
Rhynie Chert
Lower Devonian



The  Rhynie Chert04.5 
The Rhynie Chert is a formation of smooth, dark bule-grey Devonian rock (396±12 My) located near Rhynie, Scotland. It was discovered in 1912 by William Mackie. The fine-grained siliceous rock preserves an abundance of early fossil plants in their original undisturbed positions. The preservation is so detailed and complete that it is as if the plants had been photographed in an instant of time, including "live" action shots such as the ejection of sperm cells from sporangia (Figure 4.3b). The plants were preserved almost instantly by silica-rich water from rapidly rising volcanic hot springs04.6. The fossils include algae, fungi, plants and animals preserved in their natural cohabitations, preserved in microscopic detail.
The Rhynie plant fossils are in remarkably preserved 3-dimensional form including microscopic structural details, not flattened and distorted as is frequently the case with fossils. Individual cells can be seen, including stomata but not true leaves.

The vascular land plant Rhynia is a characteristic fossil of this formation. These ferns have rhyzoids but no roots, true leaves or seeds but do  have vascula and stomata on the stems. The rhyzoids of both the fossils and living species host symbiotic fungi.

Rhynia Stem
Fossil Stem
Rhynia Cross-section
Cross-section of Fossil
Figure 4.4
Rhynia gwynnevaughanii
Fossil from the Rhynie Chert
extinct phylum Rhynophyta

The rhynia fossils sometimes are preserved in dense "forests" of plants in their natural position (Figure 4.5).

Devonian-RhynieChert.jpg
Figure 4.5a
Rhynie Chert
Devonian
Rhynia gwynne-vaughanii
Figure 4.5b
Algaophyton major
Devonian
Rhynie Chert
"A branched rhizome system with a limited number of upright stems that branched dichotomously. All axes terminated in sporangia." Does not possess a tracheal system -- it is more like hydroids of modern mosses04.7.



The known examples represented in the fossil record are (Using the nomenclature of Margulis):

extinct phylum Rhynophyta. Cooksonia is often regarded as the earliest known fossil of a vascular land plant, and dates from 425 Ma, in the late Silurian Age. This phylum became extinct in the mid-Devonian (about 380 Ma). It was a small plant, only a few centimetres high. Many more examples of this phylum exist in the Rhynie Chert. They are the "oldest known anatomically preserved vascular land plants." The fine-grained quartz rocks preserve the fossils in exquisite detail, and also include many co-existing fossils of early animals (protists and arthropods) in the actual life positions. Figure 4.5 shows a thicket of Rhynia preserved in life position in the chert (size ~ 5 x 8 cm). The leafless stems had stomata.


The following nomencature follows Margulis.

Non-Vascular plants
(Subkingdom Bryata, Phyla Pl-1 to Pl-3)

Margulis suggests of the first three plant phyla that "Hornworts, mosses and liverworts probably evolved independently of one another ... and give rise to no other plant lineage." These phyla include all non-vascular plants -- that is, they do not have an organized way (xylem and phloem) to move liquids throughout the plant. As a result the plants are small in size and require dampness to grow (although they may have remarkable abilities to survive dessication).

Because these plants are small and soft-bodied, early fossil evidence is problematic and depends on special fossilizing conditons.

Pl-1 Bryophyta. Mosses are non-vascular, so they are necessarily small and must live in wet or damp areas. Reproduction  must occur in the presence of water so that the male sperm can swim to the female sex organ. The fertilized spores generally disperse in wind currents. Some mosses are also capable of asexual reproduction.

The mosses are soft-bodied and small, and so fossils are rare. Figure 4.6 is the oldest fossil moss, Pallavicinites devonicus, from the Upper Devonian (ca. 370 Ma) of New York.

Earliest Fossil Moss
Figure 4.6
Fossil Bryophyte
Devonian ca. 370 Ma


Bryophytes in Amber. The Dominican amber is one of very few sources of fossil mosses04.8. The amber was fossilized in the Eocene era (56-34 Ma) from an extinct species of Hymenaea, a large tree found in forest areas from Mexico to Brazil.

Moss  in Amber
Figure 4.7
Calyptothecium duplicatum
Fossil Moss in Dominican Amber
Eocene (56-34 Ma)


Pl-2 Hepatophyta. Liverworts. Non-vascular. The name comes from the liver-shaped head of the male spore-producing stalk. Compared with mosses, liverworts have flattened leaf-like body  attached in a ribbon-like branching structure and rhizoids which function much like roots for attachment and food uptake. The earliest liverwort fossils are mid-Devonian (Hernick et al., Earth's oldest liverworts, Review of Palaeobotany and Palynology, Volume 148, Issues 2-4, January 2008, Pages 154-162). Liverworts are the only plants that do not have proper stomata, although some have pores which, however, cannot close as do stomata.

Pl-3 Anthocerophyta. Hornworts. Non-vascular. The name comes from the horn shape of the male spore-producing stalk. Some varieties are host to nitrogen-fixing bacteria, so that they can derive nitrogen from the air and live on bare rock. This makes the hornwarts one of the first successful invaders of sterile land.

The hornworts are relative late-comers in the fossil record, first appearing in the Cretaceous Era (144-65 Ma) contemporary with the flowering plants and grasses. This seems very late from an evolutionary point of view. The "horn" is unusual because -- like grasses -- it grows from the base -- an undifferentiated "stem cell" called the meristem: most plants grow from their tips.


The earliest unambiguous fossil hornwort was preserved in Dominican Amber, dated to about 15 Ma04.9.


Vascular plants
Subkingdom Tracheata, Phyla Pl-4 to Pl-12).

All vascular plants have vascular tissue which transports nutrients and water throughout the plant. Because of this specific provision for circulation, the vascular plants can (in principle) grow much larger than the non-vascular plants -- although other changes have to accompany the provision of vascula -- such as ways to preserve and control moisture content, strengthening of cell walls for support, and ways to promote vascular flow in the face of gravity.

The vascula consist of the Xylem and Phloem. The xylem draws dissolved nutrients and water up from the soil, and the phloem moves food (mostly sugars) from the place of photosynthesis throughout the plant.

Pl-4 Lycophyta. Lycopods -- club mosses. All living lycopods are herbaceous; all woody lycopods (lepidodendrids) are extinct. Fossil woody lycopods reached over 100 ft. in height and were common in the Carbonaceous. The woody material was formed by defunct tracheids (xyla) constructed with lignin04.10.

The lycopod Baragwanathia (Figure 4.8) from the late Silurian was the first plant that had true leaves with vascular tissue04.11. It reached 30 cm. in height.



Silurian-Baragwanathia.jpg
Figure 4.8
Baragwanathia
mid-Silurian Lycopod
Lower Plant Assemblage (Australia)
   
Club Moss Pennsylvanian Modern Lycopod
Figure 4.9a
Club Moss -- Pennsylvanian Era
Llantwit seam, South Wales
Figure 4.9b
Modern Club Moss


Pl-5 Psilophyta. Whisk Ferns. There is no fossil record of this phylum04.11a.

Pl-6 Sphenophyta. Horsetails. Modern horsetails are only a dim shadow of their resplendent past which reached a peak in the Carboniferous Age (359.2 to 299.0 Ma). They first appear in the late Devonian age.

The modern horsetail fern is a genuine "living fossil" on the same order of the Gincko tree. These small plants are commonly found in woods. Like true ferns, they reproduce by spores.

The first fossils that can be unambiguously placed in the Sphenophyta are Late Devonian in age04.12. They were abundant during the Carboniferous Era (450 Ma), the giant Calamites growing to heights of over 100 ft. They became extinct in the early Permian04.13.

Carbonaceous horsetail
Figure 4.10
Horsetail Fossil
Carboniferous Era
   

Pl-7x Seed Ferns (Extinct) -- the First Seed Plants. Seed-bearing ferns are a phylum of plants -- the Pteridosperms -- that is now extinct. Ferns today are seedless -- Phylum Pl-7 Filicinophyta (Pteridophyta), the seedless ferns. This is the first appearance of seeds, and it is thought by many biologists that all seed plants descended from this phylum. Prior to the appearance of this phylum, all plants propagated sexually with spores. These are the first extinct phylum of vascular plants identified solely by examining the fossil record04.14. The Carboniferous era has been called the age of ferns -- actually, the age of seed ferns which often grew to the size of large trees.

Seed Fern
Figure 4.11
Adiantites machanekii
Seed Fern, Carboniferous Era
Teilia Quarry, England

Pl-7 Filicinophyta -- true ferns. Ferns, Pterophyta. The earliest fossils of true ferns occur in the Carboniferous era, contemporary with the seed ferns (see above). Ferns similar to modern families rose later, in the  Cretaceous era (145 to 65 Ma) during the heyday of dinosaurs, and also the era of the earliest flowering plants (angiosperms).

True Fern Pennsylvanian(?)
Figure 4.12
True Fern -- Pecopteris
Pennsylvanian Era (320-286 Ma)
Francis Creek Shale
Coal City, Illinoi

Pl-8 Cycadophyta -- Cycads. Cycads are gymnosperms -- "naked" seed plants; that is, they lack the food (derived from the ovaries) that surrounds other seeds. This phylum first appeared in the early Permian Era (299-251 Ma). "The Cycad fossil record is generally poor." -- Wikipedia. Cycads resemble ferns, but typically have fern-like leaves that surround a central seed cone. One variety is the Sago Palm (actually not a palm but a Cycad).

Cycad-Fossil Modern Cycad
Figure 4.13a
Fossil Cycad
ca. 60 Ma??
Figure 4.13b
Modern Cycad


Pl-9 Ginkgophyta -- Ginkgo tree. The modern Ginkgo Balboa tree is the only living species of this phylum which has a fossil record from the Permian Era. Note the leaf varieties in the fossil species, compared with the varieties in the modern Ginkgo Balboa -- all varieties can show up on a single tree (a similar variation occurs in sassafras trees).

Ginkgo Cordilobata
Figure 4.14
Ginkgo cordilobata
Lower Jurassic (~ 180 Ma)
Ishpushta, Afghanistan

Ginkgo Leaf Variety Ginkgo Modern Leaf Variety
Figure 4.15a
Fossil Ginkgo Leaf Varieties
Upper Cretatious and Jurassic Eras
Edward W. Berry, Smithsonian (1918)
Figure 4.15b
Modern Ginkgo Leaf Varieties
All varieties may occur on the same tree


Pl-10 Coniferophyta -- Conifers. Conifers are woody gymnosperm plants that first appear in the upper Carbonaceous era but flourish in the Mesozoic Era (250-67 Ma) between the Permian Extinction (251 Ma) and the Chicxulub extinction (65 Ma), the K-T boundary which defined the end of the Cretaceous era and the start of the Tertiary Period. The Mesozoic Era begins with the Triassic Era (250-200 Ma) and ends with the Cretaceous Era.

Conifer Fossil
Figure 4.16
Conifer Fossil
Mid-Triassic (225 Ma)
Kühwiesenkoph Fossil Repository

Pl-11 Gnetophyta. Gnetophytes are also gymnosperms. Many of them are woody climbers. The earliest clearly identifiable fossils are from the Cretaceous, but some fossils with possible identity as Gnetophytes go back to the Permian.

Cretaceous-Gnetophyta
Figure 4.17
Gnetopyte with cones and leaves
Lower Cretaceous (~140 Ma)
Nova Olinda, Brazil

 
Pl-12 Anthophyta -- Angiosperms = flowering plants. Flowering plants arose in conjunction with the arrival of bees and insects that are adapted specifically in pollenation04.15. This period is characterized by the appearance of very large animals -- it is still a feature today that the largest land animals feed on plants (perhaps because plants must be eaten in bulk in order to provide sufficient nourishment).

Archaefructus Sinensis Archaefructus Sinensis Reconstructed
Figure 4.18a
Earliest Flowering Plant
ArchaefructusSinensis
Upper Jurassic Jianshangou Bed (145 Ma)
Liaoling Province, China
Figure 4.18b
Earliest Flowering Plant
Reconstruction


Cretaceous-Eudicot
Figure 4.19
Eudicot - Leefructus mirus
Flowering Plant
Cretaceous 127 Ma
Yixian Formation, China
height 16 cm.
   
Flowering plants appear to have developed concurrently with insects that could aid in pollination. "prior to the evolution of bees [angiosperms] didn't have any strong mechanism to spread their pollen, only a few flies and beetles that didn't go very far."
04.16.

Bee Fossil Amber Bee Fossil Amber Sketch
Figure 4.20a
Oldest Fossil Bee in Amber
Melittosphex burmensis
mid-Cretaceous (100 Ma)
Hukawng Valley of Myanmar (Burma)
Figure 4.20b
Bee in Amber
Diagram



Grasses. only appear after 65Ma. A remarkable characteristic of grasses (and whisk ferns, Pl-5) is that they grow from their base rather than from the tip. Thus damage to the blades by grazing animals do not kill the grasses, because they continue to grow from the base of the blade. Other plants, such as trees, grow from the stem and branch tips.



fractal

ENDNOTES

Meiosis Overview (Wiki)  Figure 4.21 is an overview of Meiosis as it concerns the generation of haploid spores in plants. This is the reason why meiosis always results in four "daughter" spores.

Meiosis_Overview_Wiki.gif
Figure 4.21
Meiosis Overview


all land plants have alternation of generation as the reproductive cycle
     All plants have a diploid sporophye which generates haploid spores. For flowering plants, the sporophyte is the main phase of life (the plant, tree, etc.). Similarly all plants have a haploid gametophyte. The fusion of male and female gametes produces a diploid zygote which divides by mitosis into a sporophyte. In bryophytes (mosses, etc.), the "normal" mode is the gametophyte.

All plants produce spores by meiosis

Note: Dana, Manual of Geology (1896)  has a sketch of a fossil mayfly wing (p. 600). This sketch is taken from Samuel H. Scudder XIII. Relation of Devonian Insects to Later and Existing Types, in Annals and Magazine of Natural History, Vol. VII, #39, 255-260 (March, 1881). Cites Hermann August Hagen, The Devonian Insects of New Brunswick (1881), which includes a plate identical to Dana p. 600. Hagen disputed Scudder's claim that the wing is Devonian. Apparently it is in the same slab with a fern characteristic of the Carboniferous. For a modern review of the problem see Randal F. Miller, History of Geological Investigation of Saint John, New Brunswick: "Along with plants the site yielded reptile/ amphibian tracks. Arthropods, particularly insect remains, attracted attention from geologists worldwide. At the time the rocks were considered to be of Devonian age, making the insect assemblage the oldest known in the world... Subsequent work by British paleobotanist Marie Stopes (1914) in a Geological Survey of Canada Memoir proved the Carboniferous age of the rocks."]  Thus Dana misplaced this fossil in the Devonian; it should be the Carboniferous.




The Cnidaria (Coelenterata)
Phylum A-4


The Cnidaria are relatively simple animals -- they have few of the body parts of higher animals. But a defining feature of the phylum is the presence of stingers (nematocysts) used for food-gathering and other tasks. The nematocysts are complex marvels of engineering sophistication.

The Cnidaria are relatively simple animals -- they have few of the body parts of higher animals -- no enclosed digestive tract, nerve network, circulatory system, vision, skeletal structure, or appendages to aid in movement -- but they have a means of communication to coordinate actions. They are radially symmetric and digest food in an open interior sac. The phylum includes corals and jellyfish (= medusas).They are soft-bodied, but corals secrete calcium carbonates that form the hard coral reefs that house millions of individual animals. A few corals show up in the Cambrian era (520 Ma) , but become abundant about 100 My later, in the Ordovician era . The modern corals date from the Devonian era (about 240 Ma).

"The distinctiveness of cnidae, the production of which unambiguously diagnoses a cnidarian, also make them unsuitable for determining evolutionary relationships of [organisms] that otherwise seems closely related to cnidarians."

There are a large variety of nematocysts, which may even vary geographically for the same or similar species. This implies that there is a robust evolutionary mechanism at work which supports variability around a basic gene package. I conjecture that this evolutionary variation occurs primarily in the parameters of gene expression.


The Engineering of Stingers


  The geologist Buckland once marvelled at the exquisite attention to engineering detail that is revealed in ancient fossils.

“We are almost lost in astonishment, at the microscopic attention that has been paid to the welfare of creatures, holding so low a place among the inhabitants of the ancient deep…. If there be one thing more surprising than another in the investigation of natural phenomena, it is perhaps the infinite extent and vast importance of things apparently little and insignificant.”
Buckland, regarding Crinoid fossils ibid. p.441, p.445

Our own fascination is with the Cnidarians - Phylum A-4, which includes corals and medusas. All species in this phylum are radially symmetric and have stingers, called nematocytes. The cnidarians are (relatively) immobile, and gather food with stingers which inject neuro-poisons (hypnotoxin) to immobilize their victims.

The nematocysts have been called the "most complex organelles of animal cells".
05.00 They are small -- about the size of an average bacterium (up to 60 µm in length).

nematocyst
Figure 5.01
Nematocyst


A cnidarian may have many thousands of these nematocysts with various specialized functions. When fully mature they appear able to function somewhat independently of the host. Some species eat cnidarians and preserve immature nematocysts (called "kleptocnidae") for their own defensive use05.01.

The engineering challenges are as follows
05.02:

• The cell wall is super-strong, to resist extreme pressure without bursting. One scientist estimated that "the tip of the nematocyst thread is forced out of the capsule [by hydrolic pressure, although some authors assert that electrical repulsion initiates the explosion - dcb] at the astounding acceleration of 40,000g!" This is over 30 times the water pressure at the deepest part of the ocean (16,000 psi ~ 1,100 atm) and is strong enough to penetrate almost any biological structure, including shells and exoskeletons
. Despite this, water can pass through the cell wall05.03.

• A hollow tube is tightly coiled under tension inside the cell, which leads to the question: how does the coil get packed into the cell? (An analogous packing problem exists for packing of viral dna inside its capsule). This tube is packed inside-out with barbs along the inner surface (which will be the outer surface once the tube is discharged). The venom may be stored in the tube[CHECK].

• The propulsion is provided by a concentrate of calcium ions that are stored in a water-tight sac. When the cyst is triggered, these ions rush into the cell, and immediately cause a severe osmotic imbalance  so that water rushes into the cell, swelling it rapidly to the point of explosion directed through the lid. The hollow piercing barb penetrates the victim's skin; the coiled tube passes through the tube and poison is ejected through the tip of the tube or through the tube wall.[GET REFS -- is this consistent with Fig below??]

• The activation time is the fastest in the animal kingdom: the entire process is complete in 3 ms
05.04. Electric triggering causes the cell volume to increase by 10%, which opens the lid, and the dart ejects in a few µs, propelled by hydrostatic (osmotic) pressure."

• The triggering mechanism is generally a combination of mechanical and chemical response, so that discharge occurs when the trigger is touched by the right prey[FOOTNOTE: REF??]. Either mechanical or chemical response alone is not sufficient.[GET REF]

At present, the details of the nematocyst's life cycle are uncertain. Figure 5.02 summarizes one current view (expressed in general terms with some details missing). Ultimately, of course, every detail must be explained in terms of ordinary chemistry, but many questions remain.

Nematocyst Life Cycle
Figure 5.02
Model of the Nematocyst Life Cycle
Berking & Hermann Fig. 3  (2005)

There does not appear to be full concensus on the details of the  discharge mechanism -- how the remarkably rapic high pressure impulse is created. The wikipedia article credits "a large concentration of calcium ions"; the above references assume electrical repulsion and osmotic pressure; other discussions assume a role for spring tension in the coil. It seems fair to conclude that this is still an unsettled question.

Similarly the storage of the toxins, or how it enters the victim does not appear to be fully settled.




Plant Innovations
Ordovician (488 - 443 Ma) to Lower Carboniferous (Mississippian) (359 - 316 Ma) Eras.

Marine plants first appear late in the Ordovician Era, but the Devonian era (416 to 359 Ma) saw the
true "greening" of the land. The massive invasion of plants onto the continents had to wait until the ozone layer first grew to a level that could filter out the most harmful cosmic rays. This is a time in which many major innovations in plants occurred.

Plant Innovations
Figure 06
Plant Innovations
Ordovician to Carboniferous




Pollen, Spores and Seeds

Plants may have both sexual (requiring fertilization of a male and female cell) and asexual means of reproduction -- as is also the case with most single-celled species of life. Sexual reproduction of plants involves spores or seeds. The primary distinction between spores and seeds, is that spores fertilize outside the parent's body, whereas seeds fertilize and mature within or on the parent's body. [CHECK!!!] Seed plants may disperse a powder-like Pollen of male cells to provide cross-fertilization between plants, with the actual fertilization occurring within plant ovaries. This accomplishes the cross-fertilization that spores also provide.

Spores. Spores appear first in the fossil record during the middle Ordovician Era (~470 Ma). Spores form in groups of four called spore tetrads. There are two types of spore anatomy: monolete and trilete which differ in the way the original mother spore (sporophyte) divided into four[FOOTNOTE: The sporophyte is diploid (double strand chromosomes). The sporophyte divides once and then each part forms two haploid (single strand chromosomes) spores, hence four spore form togeether[FOOTNOTE: See the New World Encyclopedia entry on Spore Formation Note that ?? these spores are haploid - only half of a chromosome?? --- add Meiosis_overview pic to show 4 spores after meiosis] If they divide like orange slices, the result is a monolete spore with a single scar marking the joining point. If they divide like a tetrahedron, the result is a trilete spore with three scars marking the joining point with the other spores.

Spores Early Devonian
Figure 07
Early Devonian Spores
Jauf Formation
NW Saudi Arabia
Pierre Breuer et al. A Classification of Spores (2007)


Devonian Spores
Figure 08
Spores
Middle Devonian
Chigua Formation, Bolivia and Brazil
note trilete marks

[FOOTNOTE: For further images of pollen and spores see ref. Eckart Schrank below.]

Seeds. Seeds made it possible for plants to live away from moist environments during reproduction. [Rich p386].
All seeds are the product of fertilization and are diploid combinations of the haploid male sperm and female egg. In contrast, spores may be haploid or diploid -- that is they may form before (generally) or after fertilization [CHECK].

Carbonaceous Seed
Figure 09
Carboniferous Era Seeds



How long can pollen, spores and seeds survive?


Spores --  note two classes of spores mono and tri. etc.  intexine and exoexine
Pollen --

See http://www.benbest.com/misc/DNAamber.html Claims to get dna from amber appear to be false -- due to contamination. Not reproducible. ... There are sound theoretical reasons for believing that DNA could not survive hydrolysis & oxidation under such conditions for more than 50,000 to 100,000 years [NATURE; 365:700 (1993) and NATURE; 366:513 (1993)]. But deep ice cores taken from Greenland permafrost have revealed DNA sequences from plants and insects verified to be between 450,000 and 800,000 years old [SCIENCE; Willerslev,E; 317:111-113 (2007)]. Ice cores taken from Antarctica have the potential to reveal DNA samples that are much older. The entire human genome was sequenced from 4,000-year-old hair recovered from permafrost in Greenland [NATURE; Rasmussen,M; 463:757-762 (2010) and NATURE; Lambert,DM; 463:739-740 (2010)].Despite the discovery of lucite & epoxy resins, it has not yet been possible to artificially synthesize amber, the hardest natural resin known.

Compare viable dna from animals trapped in resin.



Wiki: Early land plants reproduced in the fashion of ferns: sporessporophyte ???

Seeds = complete (fertilized) plants, with food & protective shell [describe how].  You can see the miniature plant in, for example, lima bean seeds: split the seed in half lengthwise and you will see two miniature leaves.
germinated into small gametophytes, which produced sperm. These would swim across moist soils to find the female organs (archegonia) on the same or another gametophyte, where they would fuse with an ovule to produce an embryo, which would germinate into a

GO INTO THE PROTECTIVE, DISPERSAL FEATURES OF SPORES AND SEEDS. LONG LIVED DORMANCY.

Another difference is that self-fertilization is more likely in the process of spore-based reproduction than in the pollination of a flowering plant. The seed-based process, therefore, has more possibilities for genetic adaptation and evolution."
http://www.suite101.com/content/seeds-versus-spores-a33022?template=article_print.cfm


Remarkable exanmple: Seed Ferns vs modern ferns.

See Dr. Gerhard Leubner's website, The Seed Biology Place -- Seed Evolution for further information on seed evolution. (nte 4.14)

Development Biology of fern gametophytes -- Morphogenesis of spore maturation


plants: Alternation of Generations  26:seedless plants (.doc)
haplodiplontic = diplohaplontic = diplobiontic = dibiontic
gametophyte
sporophyte






Plant Cellular Dynamics: What Makes Things Move?
Cellular activity doesn't happen just because it "should"; every specific action in a cell is a "natural" response to physical/chemical dynamics. There are only a few basic ways that this occurs. Thus, when a particular task is at hand, that task can be described exhaustively as a sequence of dynamical tasks that are describable in terms of fundamental physical impulses. A series of sequential tasks (for example the production of sugars) requires a whole set of these things, each of which must not only do its own task, but also set things up for the next task in the sequence.

Some of the following are primitive tasks in themselves, others are composite tasks that can in turn be described as a combination of primitive tasks.

Electric potential gradients. This is a prime mover for molecular reconfiguration, conbination, motion, etc. Example: The movements of the Kinesis molecular motor. Reaction pockets within molecules based on local electrical gradients.

• Solute concentration gradients. Note that different solutes may operate independently to an extent. Example: operation of xylem and phloem in plants.

• Acidity gradients. This is excess/deficiency of H+ ions (== ph).

• Osmotic pressure across membranes. Classical examples: The cnidocyst discharge; xylem and phloem movement between cells.

• Capillary Action. xylem and phloem.

• Condensation and evaporation. Leaf transpiration via stomata "breathing."

• Semi-permeable membrane differentiation.

• Mechanical transport with specialized motor molecules. Kinesin, ATPase, Nitrogenase, etc.

Mechanical reconfiguration. Membrane gate-keepers (e.g. in nuclear membrane, cell wall).

• Key-matching. E.g. t-rna, etc.


The Mechanics of Sap Flow

capillary action

concentration gradients

osmosis

semipermeable membranes






 
fractal

FOOTNOTES
* The background is a mid-Cambrian trilobite (about 530 Ma), see Figure 0.

Mid Cambrian Trilobite
Figure 10
Mid Cambrian Trilobite
Paradoxides, length 10"
Braintree, Mass.
Trilobites are the prototypical symbol of the
Age of Fossils.

== FOOTNOTES FOR DIFFERENCE BETWEEN PLANTS AND ANIMALS ==

^n1  Dana, Manual of Geology (1896) does not attempt to make a strong distinction between plants and animals, but defines both together with the characterization, "The plant or animal, (1) endowed with life, (2) commences from a germ, (3) grows by means of imbibed nutriment, and (4) passes through a series of changes and gradual development to the adult state, when (5) it evolves new seeds or germs, and (6) afterward continues on to death and dissolution." (p. 9) In effect, this author assumes that the distinction is well-known and requires no special mention.

Ernst Haeckel recognized the problems of distinguishing plants from animals. In his History of Creation, he referred to the lower animals (Sponges, Corals, jellyfish, etc.) as "Animal Plants" or Zoophytes --  Ernst Haeckel, History of Creation (1876) Vol. II,  p. 144. It is perhaps significant that no scientist at this time could have made the distinction that Margulis makes.

^n01.1  One inference from Margulis' definition is that all plants and animals propagate sexually and that all are the product of sexual reproduction at some point in their ancestry. All plants and animals can form offspring using both meiosis and mitosis, and their life cycles include both haploid and diploid phases. Mitosis is involved in adding cells to the multicellular body, and may also figure in various forms of asexual reproduction.

^n01.2  See the CourseNotes.org Biology Outline, Chapter 32 Introduction to Animal diversity  "All animals share the unique family of Hox genes" ... morphological features: Animals can be characterized by body plans." The outline is based on A. Campbell, Jane B. Reece, et al. Biology, 7th Edition ((2005).

Topological body plans take account of cell location within the body. In effect, they build the body according to a 3-dimensional map, and distinguish body location: anterior/posterior (head/tail), left/right, and dorsal/ventral (front/back), Topological plans can result in left-right body symmetry or anti-symmetry,  body segmentation (head, thorax, etc.), organ placement, and other complex details that algorithmic plans cannot achieve. Animal body plans are topological.

The body plan of an embryonic animal first shows up in the blastula (a hollow sphere), which is entirely formed of undifferentiated stem cells. All animals (and only animals) pass through a blastula stage during their embryonic development [Margulis, p. 233]. From this stage on the stem cells immediately begin to differentiate based on position and orientation in the embryo, and locate the (future) head, legs, intestine, nerve system, etc. Thus the topological body plan is fundamental to all animals, in contrast to plants.

The body plan is controlled by a package of genes called the homeobox (hox) genes. The composition of this gene package varies by phylum (??). The hox genes control gene expression, and the parameters for this gene expression are stored in non-coding portions of the dna (i.e. these dna do not code for genes). All hox genes are headed by a dna marker of 183 base pairs called the homeobox and the corresponding 61 amino acid section of the hox proteins is called the homeodomain. This uniquely identifies all hox genes, and is essentially the same over a large swath of animal phyla "from fruitflies to man." Hox genes across the animal species forms the subject matter of evolutionary developmental biology (evo-devo).

The implementation of the body plan permits variation in development within closely defined limits. This variation is called phenotype plasticity. This variation is in addition to changes that result from radiation damage or various types of copying errors that may slip through the cell's error-checking machinery.  Apparently a mechanism exists to preserve some of these variations, so that it can (occasionally) be passed on to future generations -- probably within the non-coding portions of the dna.


^n01.3 The only exception is some Urochordates (A-35) which are small animals that live in the oceans. It is thought by some that they acquired the cellulose synthase by horizontal gene transfer from bacteria:
"Urochordates are sometimes called 'tunicates' because of the presence of an outer protective layer  named the tunic, a defining characteristic of all urochordates. The tunic is composed of tunicin, which is related to plant cellulose. Both C. intestinalis and C. savignyi contain a single copy gene (CesA) for cellulose synthase. Intensive molecular phtylogenetic analyses suggest that both Ci-CesA and Cs-CesA were acquired by an ancestral tunicate via horizontal gene transfer from bactyeria more than 520 million year ago."
Volff, Jean-nicolas, Vertebrate Genomes (Genome Dynamics),  Vol. 2, p. 204 (2006)

See also Sagane, et. al., Functional specialization of cellulose synthasegenes of prokaryotic origin inchordate larvaceans (2010) and The Evolutionary Origin of animal cellulose synthase.

^n01.4  Cellulose has been called "the most common organic compound on Earth," and lignin is the second most common.

^n01.5 Some early animals appear to have indeterminate growth, which leads to the general conclusion that size is not necessarily a mark of advancement. Modern examples may include alligators and some other amphibians.

^n01.6  See "Plant Growth" in Plant Structure and Function  (University of Illinois at Chicago): "Most animals have a pre-programmed body plan... Plants do not have a pre-programmed body plan... There are constants like leaf shape and branching patterns but you can never predict where a new branch will come about."

== FOOTNOTES FOR PROTIST PHYLA ==

^n02   Note: Many excellent illustrations of early fossils are found in the following subscription or pay-per-view sites:
Lyell Collection of the Geological Society of London.
Journal of Paleontology (Geoscience World)
Paleobiology: Journal ofthe Paleontological Society.

Chinese Cambrian formations are providing Cambrian fossils in pristine condition. Some of these are reported in the Journal of Paleontology. See also the notes at Microbiology. See footnote 3 below.

^n02.1 For many fossil and recent examples from the Carboniferous Era and later, see Michael Hesemann's Foraminifera gallery. This features many foraminifera drawings from the HMS Challenger expedition Report on the Foraminifera by Henry B. Brady (1884).

^n02.2 Margulis, p. 144 "their nuclear organization is so idiosyncratic that they have been called mesokaryotic (between prokaryotic and eukaryotic)".

^n02.3  J. Phycol. 36, 821-820 (2000) Silicon Metabolism in Diatoms  "Sizable intracellular pools of soluble silicon have been identified in diatoms, at levels well above saturation for silica solubility, yet the mechanism for maintenance of supersaturated levels has not been determined." "Perhaps part of the reason for the ecological success of diatoms is due to their use of a silicified cell wall, which has been calculated to impart a substantial energy saving to organisms that have them."

^n02.4  http://en.cnki.com.cn/Article_en/CJFDTOTAL-DZKX199103004.htm.


^n02.5   He also authored an earlier volume, also exquisitely illustrated, Die Radiolarien (1862) and Kunstformen der Natur, both posted on the web by Kurt Stüber's On-Line Library.


^n02.6  http://www.ucmp.berkeley.edu/protista/radiolaria/radfr.html; "In many species the radiolarian skeleton based on an initial spicule, with associated additional elements forming a more or less regular spherical body. The development of this skeleton can be used to differentiate major groups of radiolarians."
 
http://www.geology.buffalo.edu/contrib/people/faculty/malradio.htm

== FOOTNOTES FOR ANIMAL PHYLA ==

^n03  See The Cambrian Fossil Record and the Origin of the Phyla. Many beautiful photographs of Cambrian fossils from the Chengjiang Formation are illustrated in Hou Xian Guang, Richard J. Aldridge,  et al., The Cambrian Fossils of Chengjiang China (2004). The Chengjiang formation is particulary noted for its soft-body fossils. See on-line photos at Chengjiang Biotica. For descriptions of the various phyla see earthlife.net. See also Palaeos.org (developing website).

^n03.1  Charles Doolittle Walcott, Second Contribution to the Studies on the Cambrian Faunas of North America (1886).

^n03.2 ScienceDaily (Apr. 11, 2008). See also Rethinking Early Evolution: Earth's Earliest Animal Ecosystem Was Complex And Included Sexual Reproduction. ScienceDaily (Mar. 20, 2008): "Funisia dorothea grew in abundance, covering the seafloor, during the Neoproterozoic, a 100 million-year period ending around 540 million years ago in Earth's history, during which no predators were around."  Wiki:"A phylogenomic study in 2008 of 150 genes in 29 animals across 21 phyla revealed that it is the Ctenophora or comb jellies which are the basal lineage of animals, at least among those 21 phyla. The authors speculate that sponges—or at least those lines of sponges they investigated—are not so primitive, but may instead be secondarily simplified."

^n03.3 "The oldest ctenophore and the only embryonic comb jelly known from the [lower cambrian] fossil record" www.pnas.org/content/104/15/6289 (2007).

^n03.4 "chelicerates are defined by their jaws. Whereas most modern arthropods have chewing mouthparts called mandibles, the jaws of chelicerates — the chelicerae, which give the group its name — are usually shaped like claws or pincers and are mostly used for grasping and tearing up prey"  -- Fossil Focus - Chelicerata.

^n03.5  Orsten fauna "The initial site, discovered in 1975 by Klaus Müller and his assistants, exceptionally preserves soft-bodied organisms, and their larvae, who are preserved uncompacted in three dimensions."  For information about the Orsten fauna see Core Orsten Research.

^n03.6 03.6 A remarkable living fossil from the Cambrian Era: -- Monoplacophorans -- ancestral to later mollusc classes -- was discovered in the 1952 Galathea expedition, in which ten living species of Neopilina galathea were discovered. See the Lyell Collection, citing Runnegar & Pojeta (1974). Scaphopoda may date from the mid-Ordovician Era. See also a website for polyplacophorans.

^n03.7  From the web page “Life in the Cambrian

^n03.8  "Cambrian origin of all skeletalized metazoan phyla—Discovery of Earth's oldest bryozoans (Upper Cambrian, southern Mexico)" Geology (2010).

^n03.9 Jun-Yuan Chen et al. The first tunicate from the Early Cambrian of South China (2003).

^n03.10  Head and Backbone of the Early Cambrian Vertebrate Haikouichthys. Nature 421, pp 526-529 (2002). See also Oldest Fossil Fish Caught BBC News Nov. 4, 1999: "They are identifiable, say the scientists, because of their gills and a zigzag arrangement of muscles called myotomes, which are only found in fish."



Glenn R. Morton,  Chronology of the Cambrian/Precambrian Boundary (2000) is a chronology of the appearance of phyla.
     See also Glenn Morton's Creation/Evolution  Home Page. This is a self-proclaimed Christian refutation of the Young Earth Creationist view.

Images of Chengjiang fossils: http://www.fossilmuseum.net/Fossil_Sites/Chengjiang.htm
http://www.fossilmuseum.net/Fossil_Sites/Chengjiang/Chengjiang-Fossils.htm


== FOOTNOTES FOR PLANT PHYLA ==


^n04  John Pell, Seedless Vascular Plants. See also U. Maryland,  Historical Geology (2011). 

^n04.1 See Mega Clubmoss Flora, Wiki, History of Plants, and "Greening of the Land" Chapter XXIII of Rich, The Fossil Book

^n04.2  The discovery of spores and Boiophyton classified as Bryophyta is disputed in Paul Kenrick, et al. SEMBLANT LAND PLANTS FROM THE MIDDLE ORDOVICIAN OF THE PRAGUE BASIN REINTERPRETED AS ANIMALS Palaeontology, Vol. 42(1998), which classifies them as gorgonacean octocorals, animal phylum A-4 Anthozoa. This article also disputes the interpretation of spores from the Ordovician as indicating plants were present. For the assertion of their identity as plants see Evolution of Micro-organisms and Plants (Boiophyton Pragense).

It should be noted that "molecular clock" calculations place the earliest plants in the Ordovician Age, however this interpretation of the molecular clock is debated.


^n04.3  Rhynia (extinct phylum Rhynophyta) are fossils and spores from early Devonian silica rocks found in Rhynie, Scotland. Similar to Psilotum (Pl-5). Berkeley, Early Land Plant Fossils: the Rhynie Flora. Rhynie Chert beds in Aberdeenshire in the north of Scotland.
Aglaophyton major

^n04.4 Plant spores form from tetrads (a group of four cells) that form as a result of the gamete splitting twice into four spore cells. There are two ways that the four cells form: (1) In a tetragonal arrangement -- all four cells join at a point; and (2) In a longitudinal arrangement -- each cell is a quadrant of a sphere and join at the poles (like orange slices). When the spores separate from the tetragon, the scar left by the connection is called a trilete - three lines joined at a point. "This arrangement of cells cannot necessarily be considered definitive evidence of meiosis or sexual reproduction" because some green algae and cyanobacteria are also known to produce tetrads by asexual means (mitosis)." Thomas N, Edith L. Taylor, Michael Krings, Paleobotany: The Biology and Evolution of Fossil Plants 2nd Ed. (2009) p. 62.  "[T]o date the oldest spore assemblages believed to have been produced by some land-inhabiting plant occur in lower middle Ordovician (Llanvirn) rocks.... commonly referred to as cryptospores." ibid. p. 189.

Micropaleontology 24 #3 (1978), Silurian trilete spores and plant fragments from northern Indiana, and their paleobotanical implications.

^n04.5  For information about the Rhynie Chert see The Palaeobotanical Research Group of Münster Germany, The Rhynie Chert and its Flora. Also see The University of Aberdeen The Rhynie Chert, University of California Museum of Paleontology (Berkeley) (UCMP), Early Land Plant Fossils: the Rhynie Flora and Rhynie Chert beds .

^n04.6 "The silicification process must have occurred very quickly, within a few days or even much less, because even very delicate plant structures and also very short-lived life and developmental stages have been preserved, like germinating spores, freshly released sperm cells and developing arbuscles of vesicular arbuscular mycorrhiza. The higher land plants do not only show many details of their anatomy but also their ontogenetic development.  In several cases whole life cycles can be studied.  Some of these life cycles are now even better known that those of many extant plants." The Rhynie Chert and its Flora.

^n04.7  Peter H. Raven, et al. Biology of Plants p. 378

^n04.8 Frahm & Newton A New Contribution to the Moss Flora of Dominican Amber, The Bryologist 108(4):526-536. 2005. This article contains numerous illustrations, including the one shown here .

^n04.9  Taylor, et. al, op. cit. p. 166.

^n04.10  The Wikipedia article, Evolutionary History of Plants, has an interesting functional/mechanical description of the development of the trachea.

^n04.11 "The presence of Baragwanathia and its possible mid-Silurian age have caused significant discomfort and debate among paleobotanists."  -- UCMP, op. cit.  See also Plants invade the land: evolutionary and environmental perspectives  By Patricia G. Gensel, Dianne Edwards: (p. 103) "Questions remain concerning the age of the Lower Plant Assemblage [of Australia - dcb], partly because of the presence of identical plant types in sediments of such disparate ages [i.e. Posonchong Devonian Floral Assemblages - dcb]. If the [Australian] Lower Plant Assemblage is correctly dated, such a complex form as Baragwanathia differs considerably from the types of fossils being found in Silurian sediments in other parts of the world. It further implies that some plant types would have existed unchanged for more than 20 million years." 

^n04.11a  UCMP, op. cit.
 
^n04.12  UCMP, op. cit.

^n04.13  Dana, Manual of Geology (1896) puts Calamites in the Devonian of Ireland. (p. 626). Later (p.654) he states, "At Carbondale, in Pennsylvania, a forest of Calamites, or tree-rushes, was cut through in opening an inclined tunnel through sandstone to the underlying coal-bed, and the trunks, or rather their fragments, were so numerous that they were used as a foundation for a tramway for transporting the coal out of the mine. In the walls crowds of other stems of the old jungle were left. Lesquereux refers the species of Calamites to C. Suckovi and C. approximatus. He also states that in the roof-shale of the coal-bed at Carbondale, Pa., there was found an impression of the bark of a Lepidodendron, two feet wide and seventy-five feet long." See examples of the stigmaria on the Lepidodendron trunks ( e.g. p.670).

^n04.14 See Dr. Gerhard Leubner's website, The Seed Biology Place -- Seed Evolution for further information on seed evolution.

^n04.15 "Flowering plants exhibit a number of evolutionary innovations that appeared rapidly, including novel structures like carpels and primitive petals and sepals, the sine qua non of flowering plants," dePamphilis said. Angiosperms also boast plenty of unique biochemistry. "They're a rich source of medicinal compounds. Even the kind of wood they make is special." -- The "Abominable Mystery". This phrase was used by Darwin with reference to the origin of flowering plants. The oldest flowering plants appear in the fossil record at the very start of the Creataceous Era, about 145 Ma. By the upper Cretaceous (around 65 Ma), many of the extant angiosperm families and subclasses had already differentiated. This is considered the rapid radiation of the angiosperms which proceeded to become the dominant component of the world's flora. In many if not most instances, specific angiosperm plant species arose in conjunction with specific insects and other creatures which adapted specifically to forage on them. "Angiosperms and insects are a good example of coevolution." -- Wikipedia. So, for example, bees first appear in the fossil record at about 100 Ma.

^n04.16   ScienceNews, October 26, 2006.

04.17  ^n04.17  nn

04.18  ^n04.18  nn

04.19  ^n04.19  nn

^n05.00 Stefan Berking & Klaus Herrmann, Formation and dischare of nematocysts, (2005)

^n05.01 "Certain types of sea slugs, such as the nudibranch aeolids, are known to undergo kleptocnidae (in addition to kleptoplasty), whereby the organisms store nematocysts of digested prey at the tips of their cerata." http://www.answers.com/topic/nematocyst

^n05.02 Following Fautin and Shimek

^n05.03 Dispersal of spores (since mid-Silurian) is a similiar type of specialized mechanism using hydrophobins for spore ejection -- see Wiki article on trilete spores "The forcible discharge of single spores termed ballistospores involves formation of a small drop of water (Buller's drop), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000 g." See Plant Spores.

^n05.04 Berking, ibid. Also Kurz, et. al., Mini-Collagens in Hydra Nematocytes, (1991): "The explosive discharge of cnidarian nematocysts is one of the fastest and most spectacular events in biology. High speed cinematographical analysis has shown that the whole exocytotic process takes <3 ms (Holstein and Tardent 1984)."

05.05  ^n05.05  nn

05.06  ^n05.06  nn

05.07  ^n05.07  nn

05.08  ^n05.08  nn

05.09  ^n05.09  nn

06   ^n06  n

07   ^n07  n

08   ^n08  n

09   ^n09  n

10   ^n10  n






13   ^n13  In 1991 the International Subcommission on Cambrian Stratigraphy officially set the Cambrian boundary at the first appearance of  Trichophycus fossil burrows (Figure ).

14   ^n14  n

15   ^n15  n

16   ^n16  n

17   ^n17  n

18   ^n18  n

19   ^n19  n

fractal.gif

REFERENCES

James D. Dana Manual of Geology (1896) -- many fossils presented in systematic manner. See in particular the illustrated contents.

Berry, Edward W., Paleobotany: A Sketch of the Origin and Evolution of Floras. Smithsonian Report 1918, 289-407.


Historical Geology: The History of Earth and Life
(U. Maryland, Spring 2011)

James W. Hagadorn Burgess Shale: Cambrian Explosion in Full Bloom (2002)
Hou Xian Guang et al. The Cambrian Fossils of Chengjiang China, Blackwell (2007).
Lynn Margulis, Kingdoms and Domains,



Patricia & Thomas Rich, Mildred & Carroll Fenton, The Fossil Book: A Record of Prehistoric Life, Dover, (1996), Chapter XXIII p. 372ff; XXXII, p. 534ff).
Colin Tudge, The Variety of Life, Oxford, 2000.
Thomas N. Taylor, Edith L. Taylor, and Michael Krings, Paleobotany: The Biology and Evolution of Fossil Plants. (2009).

On-line Museums:
The Virtual Fossil Museum
Melbourne Museum
Natural History Museum of Berlin: Paleobiology Database
Microscope Image Gallery
Web Geological Time Machine (Berkeley U)
Hans' Paleobotany Pages (Hans Steur)
University of California Museum of Paleontology (UCMP).
Mrs. Dotson's Science Page --  20:EvolHistLife (.doc)  26:seedless plants (.doc)

David C. Bossard, Abundant Life: The Diversity of Life in the Biosphere, IBRI Colloquium lecture (2001). PDF versions: text, slides.
David C. Bossard, The Chemical buildingblocks of Life. IBRI Colloquium lecture (2001)
David C. Bossard, Geology Before Darwin: The Struggle to Find and Defend the Truth about the Earth’s Past IBRI Colloquium lecture (2003)
David C. Bossard, A Fit Place to Live: Creation of the Biosphere IBRI Colloquium lecture (2003)
David C. Bossard, The Stones Cry Out: How Early Christian Geologists Enlarged their Understanding of the Creation Account IBRI Colloquium lecture (2006)
Daphne Gail Fautin Structural Diversity, Systematics, and Evolution of Cnidae, Elsevier, (2009)
S.M.Gon, Pictorial Guide to the Orders of Trilobites
Stephen Jay Gould, Wonderful Life: The Burgess Shall and the Nature of History (1989).
Nigel C. Hughes, Trilobite Construction: Building a Bridge across the Micro- and Macroevolutionary Divide, (2005) In my view this article follows classic evolutionary reasoning in contrast to the approach implied by evo-devo.
Lynn Margulis, Kingdoms and Domains, An Illustrated Guide to the Phyla of Life on Earth, 4th edition (2009)
Riccardo Levi-Setti, Trilobites, (1993).
Patricia & Thomas Rich, Mildred & Carroll Fenton, The Fossil Book: A Record of Prehistoric Life, Dover, (1996), Chapter XXIII p. 372ff; XXXII, p. 534ff).
J. William Schopf, Cradle of Life: The Discovery of Earth's Earliest Fossils (1999).
Colin Tudge, The Variety of Life, Oxford, 2000.
Hou Xian Guang, Richard J. Aldridge, et. al. The Cambrian Fossils of Chengjiang, China. Blackwell, (2007).

Wikipedia Articles:  Animals (Describes the various animal phyla,



Wikipedia Articles:  Animals,

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Posted August 18, 2011