Posted dd Mmmm 201?, Revised December, 2010


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

Chapter 12
    Development of the Animal Classes*


Remarks on the Animal and Plant Classes
The description of the basic plant and animal body plans -- the phyla -- which is the subject of earlier chapters, is too general to convey a good understanding of the creation narrative, which includes a great diversity beyond just the variety of body plans01. The classes (or orders) are the first level of refinement, and carry the narrative a step further. When do they arise in the fossil record? What innovations are required? Do these innovations require basic changes in the genetic makeup or are they natural modifications of existing genes and gene packages?

Of course the narrative goes on beyond even this level, but already here the limitations of our present knowledge are daunting, and it might hint of masochism to go much further. In particular, at present the existence of many changes can only be pointed out; the way that they came about is largely unknown: did the changes involve new gene packages that were previously unknown, or were they "tweaks" of existing genes, or of the regulatory structure? Why do so many of the new innovations seem to spring up as "magnates" of the new classes?

There is little doubt that many of the present gaps of understanding will be filled in the coming decades and centuries, and I for one look forward to these gains. At the same time the lack of deep insight into how natural evolution works makes it difficult to understand the limits of natural development.

The (Temporary) End of the Secular Creation Narrative

The science of cosmology is almost entirely the product of the past 60 years. It has formed the basis for the creation narrative presented in this website. Our narrative is (nearly) at an end because we are now hitting the frontiers of the mature parts of that narrative.

The main missing ingredients are these:

(1) A detailed timeline of the principal innovations in living species (plants and animals). Thus far only the most dominant peaks of this innovation can be discussed with any degree of completeness. There are dozens, perhaps hundreds more major -- perhaps astounding -- innovations yet to detail. Some may be plainly visible, but (I suspect) many others hidden. We can see the effects in the plants and animals around us, but the deeper details of how and when they came about are very sketchy. Major efforts to understand these innovations are ongoing, but the field is so vast it will be many decades, at least, before a reasonably rounded picture emerges.

(2) A correlation between this timeline of novel innovations and the specific genetic or regulatory changes that occurred to effect them. Ideally, one would like to see a spreadsheet with the innovations listed together with the major genetic changes that accompanied those innovations.

Several things delay the production of such a spreadsheet:
a. The relatively recent development of the ability to sequence genes -- as a result there is a natural logistic backlog of thousands of species that are as yet unsequenced;
b. The difficult task of identifying the functions of the sequenced genes and the association into gene packages. Most genes and gene products operate collectively rather than singly. In addition, many genes perform more than one function.

A fundamental difficulty is that the end result of genetic change is only indirectly tied to the responsible genes -- first find the dog, then identify the tail, and finally locate the wag. Life functions are a rabbit-warren of indirect effects and causes.

(3) A specific narrative about the symbiotic correlation between plant and animal (especially insect) changes, and explanations of how this occurs in practice. One needs, for example, to distinguish between so-called "convergent evolution" (which is largely unexplained) and evolutionary development*.

(4) A detailed and accepted "tree of life" based on genetic relatedness. In the past decade there has been great progress in the detailing of this tree of life using cladistics. But at present these valuable investigations have not congealed into a single generally-agreed storyline. Ultimately, one can expect that a generally accepted tree based on cladism will replace the traditional tree based on physical similarity, that until recent decades has been the main way that species relatedness has been inferred.

(5) Explain exactly how such changes are recorded and implemented in the genetic code or in gene regulation. There is overwhelming evidence that it is NOT just a matter of environmental pressure and "survival of the fittest": too many changes occur too rapidly for that slow approach to gain traction, particularly in higher species which often are associated with much reduced rates of reproduction. This is the great unfinished business of evolutionary theory.

As a result of these limitations, the narrative as regards the development of classes, orders and subdivisions below the basic body plans (phyla and certain classes) is spotty. The future is bright with anticipation of greater insight, but the present we must be frustrated in our desire to complete the creation narrative.

* Consider, for example, the "old" narrative about convergent evolution in the octopus eye, versus the current view of evo-devo, that all eye development in widely separated species uses the same highly-conserved package of hox genes. This is not, of course, the full story of how these changes occur, but it certainly is a change from the older view.


The intent of this chapter is to give a timeline for major innovations in the plant phyla, particularly the angiosperms, and to describe these innovations both as to what they achieve, the major molecular innovations involved, and the genetic changes required to produce and carry out these innovations.

In earlier chapters, the sort of treatment desired has been carried out in some aspects of the central dogma, in the discussions of the eukaryotic cell innovations, and to a very limited extent in some other special topics (the development of stingers in the cnidaria, for example), leading to a number of sharp points that have been noted at the appropriate places.

Unfortunately, perhaps due to my own lack of comprehensive experience, combined with what appears to be a very immature level of development in the science that would allow such a discussion (after all, complete genome sequencing has only been possible in the past decade or so), this intent is difficult to carry off, and as a result this chapter is unsatisfyingly incomplete, if not outright premature. Hence the scarcity of sharp points -- I believe they are there, but they must await further information.

I will therefore leave it incomplete -- as a marker, perhaps, for future additions, posting whatever remarks I can glean from the available information, in the hope (confidence?) that more material will become available soon.

This chapter considers the fossil evidence for diversification of the animal phyla into the major Classes -- fishes, insects, mammals, etc, and also expands the Class of Mammals to the next level. The full Creation Narrative of course extends  onwards to further levels of classification, but we will stop at this level of detail (see Figure 1)02.

Figure 1

It should be remarked at the start that an attempt to understand the role of evolution in this Narrative is doomed to frustration, at least at present, because of the rather primitive level of understanding of the basic mechanisms of how evolution really works its changes. So the discussion is fated to be a bit incomplete. Ideally, one would like to be able to describe just how (even in general terms) an "innovation" in an animal class, order, etc. gets passed on to its descendents, but, in fact, that critical piece of information is just not known. Or to put it another way, one way that it isn't done has been amply demonstrated in the Cult of Lysenkoism which distorted science in the Soviet Union for half a century.

To take a more positive view, it is evident that the general plan of the Creation Narrative is: each animal class fulfills a need of the project of life and to maintain a balance in nature. No plant or animal can multiply unchecked, and no waste product can go unused. By necessity all biological life must feed on other biological life or on life's waste products. The earliest plants and animals fed on bacteria and single-celled protists -- primarily algae. Thus one finds the worms, trilobites and other animals that feed on this simple matter. Very soon, animals arise that feed on other animals as well, and the early animals develop armor and other defenses against hostile attack. As animals increase in size and defenses, new animals appear with jaws and teeth that can handle that increased challenge. This is the general plan for advancement. In parallel, gradual changes in how animals procreate and care for their offspring also develop, moving from offspring that largely fend for themselves, to the development of animals that parent their offspring in various ways, and finally to mammals which both gestate and nourish their offspring.

The fossil record provides a revealing narrative of how these developments of the Creation Narrative occurred in time. The remainder of this chapter describes how the more prominent animal classes appear in the fossil record. See Fossil Illustrations of the Plant and Animal Classes for many illustrations contained in 19th Century Geology books.

Porifera (A-3). The Sponges. Sponges appear as early as the lower Cambrian (Figure 2). The Classes are based on the type of skeleton: Hexactinellida (glass sponges = silica spicules), Calcarea (calcium carbonate bodies and spicules), Demospongea (silicate spicules or spongin fibers; sometimes massive external CaCO3 skeletons) [Wiki].  The siliceous sponges use silicatein enzymes03 to form the slicon spicules and other characteistic silica threads. The silicatein enzyme has 330 amino acids and is produced by a 2,280 bp gene including 6 short introns. It appears to become active in the presence of iron and silicon ions.

The order of appearance in the fossil record is: Hexactinellida first, then Demospongea and finally Calcarea. All appear in the early Cambrian.

    Class Hexactinellida. This is possibly the oldest sponge class, with "probable" examples found in the Ediacaran Formation in South Australia04. Figure 2 is an example from the Ordovician. The longitudinal threads are composed of silica.

Cambrian Sponge (Dana, Fig. 506)
Figure 2
Ordovician Sponge
Archaeoscyphia Class Hexactinellida
Dana,  p. 497

        Class Demospongea A mid-Cambrian fossil is shown in Figure 3. Note the characteristic silica threads (silicious spicules) along the body axis.

Walcott(1886) Middle-Cambrian Sponge
Figure 3
Mid-Cambrian Sponge
Leptomitus, Class Demospongea
Parker Slate, VT
Walcott Cambrian Fauna (1886), Plate 2 & p.089
See also Dana p. 470 
Garcia-Bellido (2007)

    Class Calcarea. These are the only sponges with Calcium Carbonate spicules. The fossil record begins in the lower Cambrian [UCMP Berkeley], but the record of unambiguously identified Calcarea is relatively poor. Some confusion can exist between fossil Calcarea and fossil Corals.

Coelenterata (A-4) (Cnidarians). The Cnidarians are named for their stingers (cnidoblasts are cells which contain the nematocyst stingers), which are characteristic of the phylum and come in many forms, sometimes exquisite engineering marvels. There are five classes: Anthozoa (corals & sea anemones), Cubozoa (sea wasps), Hydrozoa (hydras), Scyphozoa (true jellyfish), and Staurozoa (stalked jellyfish). Many of the species have elaborate life cycles, which makes them a favorite subject in zoology. The cnidoblasts are marvels of engineering and use a variety of ingenious mechanisms to activate the stingers -- see The Engineering of Stingers.

    Class Anthozoa (corals & sea anemones). The fossil record for corals goes back to pre-Cambrian times. Because they form reefs, they are easily preserved, unlike the other classes of Cnidaria.

Ordovician Corals (Ramsay)
Figure 4
Silurian Corals

    Class Hydrozoa (hydras)
The oldest jellyfish with preserved softbody parts was discovered in Utah in 2007 (Figure 5). It is dated to 507 Ma. Other fossils in this same formation show nematocyst cells. The report of this fossil also found fossils attributed to Classes Cubozoa and Scyphozoa at this same site, suggesting that the Coelenterata classes were already in place by the end of the Cambrian Age.

Cambrian jellyfish
Figure 5
Cambrian Jellyfish (507 Ma)
Class Hydrozoa
Marjum Formation Utah
bar = 5 mm


    Class Cubozoa (sea wasps)
Class Scyphozoa (true jellyfish) -- Also found in the Marjum Formation (See Figure 5).

    Class Staurozoa (stalked jellyfish -


Two phyla plus the extinct phylum of trilobites (here considered part of the Chelcerata) form the super-group of Arthropods. The (present-day) divisions are shown in Figure 6. By far the Insecta class holds the greatest number of species.

Figure 6

Margulis divides the Arthropods into A-20 (Chelicerata) and A-21 (Mandibulata). Trilobites would be related to A-20.
Chelicerata (A-20) (Cheli = Claw). There are three classes of Chelicerates: Meristomata, Pycnogonida, Arachnida plus the palaeozoic class of trilobites.

       Palaeozoic Class Arachnomorpha (Trilobita)
05. Trilobites are the iconic fossils. They suddenly appear fully formed in the early Cambrian (540-490 Ma) and continue until they become extinct at the end of the Permian (250 Ma). Over this span of 300 My, many changes occur, particularly in the eyes, which evolve from holochroal to schizochroal, so that most (all?) of the trilobites have the advanced schizochroal eyes in the end -- incorporated in the trilobite order Phacopida (genus phacops)06. Figure 7 shows sketches of several of the early trilobites, shown in relative size, which ranged from 1 to 25 or more cm.

The trilobites have primitive mouths with no chewing parts; on the other hand they have a through gut, and other internal organs that might be considered somewhat "advanced." It appears that they are bottom-foragers who feed primarily on microscopic and small food particles.

Jurassic Coelacanth (Wiki Commons)
Figure 7
Cambrian Trilobites
Class Trilobita (Extinct)
(All to same scale)
Dana, Geology (1896), p.473 & 476

    Class Merostomata (horseshoe crabs). The larvae of the horseshoe crabs pass through a "trilobite" stage in which they resemble trilobites. The shell is tough but flexible, horn-like chitin, unlike true crabs which have a brittle calcium (???) shell.

Ordovician Horseshoe Crab
Figure 8
Chelicerata Class Merostomata
Ordovician Horseshoe Crab (445 Ma)
Manitoba, Canada

     Class Pycnogonida (sea spiders).
The sea spiders have almost no fossil record. They have so many unusual features that some do not even consider them to be chelicerates. They have a simple heart but no gills. The gut extends through the long legs with an anal opening in the tail, which appears to serve no particular function. It is not known whether the sea spiders are an example of reductive evolution (having lost many standard body parts) or are exceedingly primitive (an early branch of the phylum). All other chelicerates have a full development pattern with the hatched larva very similar to the adult. In contrast, the sea spider larvae have only two pairs of legs and otherwise look quite different from the adults. A small silurian fossil was reconstructed by building up successive slices of the fossil embedded in rock, using computer tomography. The result closely resembles modern species07.

Ordovician Horseshoe Crab
Figure 9
Chelicerata Class Pycnogonida
Lower Devonian Sea Spider

   Class Arachnida (Spiders, scorpions).
A Sea Scorpion from the Silurian Age (Figure 10) was reported in 2011 to include actual molecules of chitin, advancing the earliest date of a preserved complex biomolecule by almost 400 My08.
Figure 10
Chelicerata Class Arachnida
Silurian Sea Scorpion (417 Ma)

Carboniferous Scorpion (Buckland 46')
Figure ??
Carboniferous (ca. 300 Ma)
Buckland Geology (1837), Plate 46'
The Sea Scorpion belongs is an extinct order of  Arachnids found as early as Ordovician Age (some claim that there are Cambrian examples). These include the largest arthropods that ever lived. An 18 inch fossil claw from the lower Devonian (390 Ma), found in 2007, would equate to a sea scorpion over 8 feet in length -- larger than a human09.

A recent discovery of a small spider fossil in Inner Mongolia, China is shown in Figure 11. This fossil is from the Jurassic (165 Ma). The spider is preserved in amazing detail (see the leg detail).

Eocene Wasp Florissant Beds (CO)
Figure 11
Spider fossil, Family Plectreuridae
Eoplectreurys gertschi, body length 3 mm.
Jurassic (165 Ma), Inner Mongolia, China
Note: Insert is magnified view of a leg showing high detail. (2010)
Naaturwissenschafter (2010) 97:449

Mandibulata (A-21)
(Chewing arthropods). Chitin exoskeletons. Three Classes: Insecta (Hexapoda), Crustacea, Myriapoda

Class Insecta (Hexapoda). The insect body plan has three segments (head, thorax and abdomen), 3 pairs of legs and 1 pair of antennas. The abdomen itself has eleven segments. The oldest fossil insect was found in the Rhynie Chert, in the early Devonian period (407-396 Ma). Other "firsts" are: First flying insect -- fossil dragonfly -- in the lower Carboniferous, 380 Ma; oldest fossil bee in the Cretaceous, 100 Ma. Wikipedia notes: "What seems most fascinating is that insects diversified in a relatively brief 100 million years (give or take) into the modern forms that exist with minor change in modern times. ...There have been four super radiations of insects: beetles (evolved ~300 million years ago), flies (evolved ~250 million years ago), moths and wasps (evolved ~150 million years ago)."

One of the most remarkable inventions of the flying insects is resilin, an elastic protein with a length of 620 amino acids. It is the most efficient elastic protein known -- only 3% of the stored energy is wasted in heat -- far better than rubber or any other known elastic material. In addition it is remarkably durable, and does not lose its elasticity with stretching or repeated use. It is estimated that the resilin in a fly can be stretched 500 million times over its lifetime without damage. Resilin is not produced by the adult insects -- it is a carryover from the larval stage

Insect Flight

The remarkable mechanics of insect flight. 11
18_2_91-97.pdf: Jerry Bergman, Insect Evolution: a major problem for Darwinism. ( -- young earth) TJ Technical Journal, 18 (2) 2004
"The insect wing is a complex, well-designed structure43 and the insect’s ability to fly is a mystery that is only now being unravelled.44 Made out of an extremely light, but amazingly strong, tough material called cutin, wings are reinforced by a complex set of various veins that provide structural support where needed, yet resist bending and twisting to supply the needed strength.45,46 The 30-odd wing muscles housed in the thorax are the most powerful muscles known per square millimetre of cross-sectional area. Although 200 times per second is typical in some insects, they can beat as fast as 1,000 times per second.47 ... The origin of the insect wing and insect flight is ‘one of the most controversial topics in paleoentomology’  ...  Because bird wing bones are homologous to animal limbs, it was long assumed that bird wings evolved from limbs.50 Insect wings, though, are not modified legs, but structures additional to the legs.51." [insect wings are readily fossilized, so abundant (altho generally pieces, not whole] ... among the hundreds of thousands of recognized insect species, nearly all can be placed in one oranother of the approximately thirty well-characterizedorders. ... Another problem is that insect wings do not function independently, but must articulate appropriately with the body, and must also function as a unit, which requires coordination by a nervous system of great complexity. The energy needed for flight is also enormous—as much as 100 times that needed for resting. ... the folding wing is, in the words of a University of Chicago neuroethologist, ‘the most morphologically complex joint in the animal kingdom’.59 A variety of folding systems exists, including longitudinal and transverse, all requiring unique muscle and nerve designs. 60 The fossil record shows that folding wings have always existed in insects—from the earliest forms found until those of today."

Fossil Dragonfly. Fully-winged species appeared suddenly in the Carboniferous (380 Ma). These fossils are the first representatives of winged flight. Dragonflies (and mayflies) have fixed wings -- they do not fold -- and they fly with a "rowing" muscle system at the root of the wing. Most other insects have specialized muscles in the wing which aid them in folding12. A startling example is the very large dragonfly-like insects with gossamer wings (Figure 12, cp.  Figure 6 (L)). These are the largest insects that ever lived.

Figure 12
Carbonaceous meganeurid dragonfly
(sub-)class Paleoptera
reconstructed (falsified) fossil
body length 1 ft. wingspan 2.5 ft.
Inset shows actual fossil -- most fossils are fragmentary.

Fossil Cockroach.
The oldest fossil cockroaches are found in the Mississippian (lower Carboniferous) age, about 350 Ma.  Figure 13 shows the largest and oldest complete fossil cockroach from a coal mine dated in the late Pennsylvanian (upper Carboniferous), about 300 Ma, discovered in Eastern Ohio in 2001. The earliest fragments are generally wing parts, which are made of chitin which preserves well and is not easily digested.

Carboniferous Cockroach (OhioStateU, 2001
Figure 13
Arthropleura pustulatus
Upper Carboniferous (300 Ma)
length 3.5 inches
Class Insecta

Fossil Butterfly.
The earliest fossil butterfly is from the Eocene, about 40 My. The fossil pictured in Figure 14 is from the Florissant Fossil Beds in Colorado and was discovered in 1887 by Charlotte Hill.

Eocene Butterfly
Figure 14
Earliest Butterfly, Class Insecta
Eocene (39 Ma) (wingspan 1.0 in.)
Prodryas persephone
Florissant Fossil Beds (CO)
NIH PubMed  NPS (2012) Wiki

Fossil Wasp.
Eocene Wasp Florissant Beds (CO)
Figure 15
Fossil Wasp, Class Insecta
Eocene (39 Ma) (scale = 1 cm.)
Florissant Fossil Beds (CO)
NPS  Wiki

     Class Crustacea (crabs, shrimp, lobsters). Crustacea have 3 segments with 2 pairs of antenna from head; a  hard (calcium carbonate strengthening of cutin) molting exoskeleton; each segment may have appendages -- antennae, legs. etc.; and an open circulatory system. Principle subclasses are: Brachiopoda (brine shrimp, water fleas), Ostracoda, Copepoda, Cirripedia (barnacles), Malacostraca (lobsters, crayfish, crabs, krill).

Fossil shrimp are known from the Jurassic Era (Figure 16). The oldest fossil krill and true crabs also date from the Jurassic. Lobster fossils date from the Cretaceous, some 50 My later (Lower Cretaceous, 110 Ma)13.

Eocene Wasp Florissant Beds (CO)
Figure 16
Fossil Shrimp, Class Crustacea
Middle Jurassic (164.7 to 161.2 Ma)
Archeosolenocera straeleni
La Voulte Lagerstättte, France

    Class Cirripedia (barnacles) Barnacles are mostly indirectly evidenced in the destruction that they cause. There is evidence that seems to be barnacle damage as early as the Devonian age. The oldest "widely accepted" barnacle is from Silurian age, although some disputed fossils have been identified as early as the Cambrian14. A fossil called Priscansermarinus barnetti from the Burgess Shale, is a proposed relative of gooseneck barnacles. The fossils from the Cambrian and Silurian are "naked" and (in my view) somewhat arguable as to identity.

    Class Myriapoda (centipedes, millipedes) Figure 17 is a millipede from the mid-Pennsylvanian, ca. 305 Ma.

Pennsylvanian-Miriapod Mazon Creek
Figure 17
Millipede Pleurojulus Sp
mid-Pennsylvanian (305 Ma)
bar = 1 cm.
Mazon Creek, Ill. Carbondale formation

Annelida (A-22) (Segmented worms). Three Classes: Polychaeta (= many bristles) (Bristleworms), Oligochaeta (= few bristles) (incl. earthworms), Hirudinea (leaches). "Because the annelids have soft bodies, fossilization is exceedingly rare" - Wiki.

Class Polychaeta (Bristleworms). "Definite polychaetes appeared in the Cambrian."

  Mississippian Polychaete
Figure 18
Mississippian (350 Ma)
Bear Gulch, Montana

Figure 19 shows annelid worm tracks from the Silurian. Figure 19b is an illustration published in 1844, and appears to be a sketch of the actual fossil from the National Museum of Wales (Figure 19a).

Collage of Fossils (Mantell) Plant History
Figure 19a
Annelid Worm Tracks
Nereites cambrensis
Silurian (ca. 425 Ma)
Figure 19b
Annelid Worm Tracks
Nereites cambrensis
Silurian (ca. 425 Ma)
Mantell, Medals of Creation (1844) p. 524

Class Oligochaeta (incl. earthworms). Wiki: "The earliest good evidence for oligochaetes occurs in the Tertiary period, which began 65 million years ago."

Class Hirudinea (leaches). The "Oldest Known Leech" is from the Pennsylvanian formation of Mazon Creek.

Mollusca (A-26). 
Three major classes: Bivalvia (Bi-valves -- valves are on the left/right sides hinged at top) no defined heads; Gastropoda (stomach-feet); and Cephalopoda (head-feet). Other less populous classes are: Monoplacophora, Polyplacophora, Rostroconchia, Scaphopoda, and Aplacophora. Body plan includes a head-foot with sensory and motor organs, viscera with a complete thru-gut digestive system, a mantle which generally secretes a hard, calcium-based shell, and a radula (toothed tongue -- not present in bivalves).

Molluscs are a favorite of geologists because they appear throughout the geological column, and provide many characteristic marker fossils that can be used to identify the various strata. There is a general progression of complexity among the three classes, with the Bivalves having the least complex systems to the Cephalapods having the most complex -- well-developed nervous and sensory systems. The octopus brain and eye are among the most advanced in the entire animal kingdom, with the octopus eye quite similar to the human eye. At one time this was considered to be an example of convergent evolution (the development of analogous structures), but with the recent understanding of evolutionary development (evo-devo) it is now known that the development of eyes and appendages, as well as other features, are directed by highly conserved hox genes.

Mollusc fossils are found in the Ediacaran Era, predating the Cambrian explosion.


   Class Bivalvia (Bi-valves) no defined heads.

Figure 20
Ordovician Bivalves
Dana, Geology (1896), p. 511

Mississippian Polychaete
Figure 21
Class Bivalvia -- Aviculopecten
Lower Carboniferous (350 Ma)
Logan Formation (Wooster OH)

   Class Gastropoda (stomach-feet)

Collage of Fossils (Mantell)
Figure 22
Class Gastropoda -- Pleurotomaria
Silurian -- Wenlock Limestone
Mantell (1844) p. 425

   Class Cephalopoda (head-feet) nautilis, Ammonite (extinct),  octopus, squid. Some Cephalopods have well-developed brains and sensory systems. They are "the most evolutionarily advanced animals to be found among the invertebrates."

The nautilis chambers (Figure 23) has been offered as an example from nature of the Fibonacci series, however that appears to be in error
15. Ammonites sometimes serve as index fossils. The earliest Ammonites appeared in the Devonian (400-360 Ma) and they became extinct at the KT boundary (65.5 Ma).

Jurassic Nautilis (Buckland Pl. 32)
Figure 23
Nautilis showing Chambers
Upper Jurassic (ca. 145 Ma)
Buckland Geology (1837), Plate 32

Figure 23a
Class Cephalopoda
Dana, Geology (1896), p. 782

Bryozoa (A-29). Three major classes: Stenolaemata (Cyclostomata) = calcified colonies of individual bryozoan zooids; Gymnolaemata = uncalcified; and the Cheilostomata. Bryozoans are generally colonial zooids less than 1mm long, have a U-shaped gut with the anus just behind the mouth; tongue-like probe with called the lophopore, supplied with cilia to create currents to bring fine particles to the mouth. The oldest Bryozoan fossils come from the Ordovician.

   Class Stenolaemata (Cyclostomata). Figure 24 shows fossilized colonies of this class from the Ordivician.

Figure 24
Bryozoan Colony Fragments
Class Stenolaemata
Dana, Geology (1896), p. 506

. Since this class is "naked" the fossil record can be presumed to be sparse.

Class Cheilostomata. These Bryozoa first appear in the late Jurassic [Wiki].

Figure 25
Upper Jurassic (140 Ma)
Class Cheilostomata
Inset: Linulite (convex side) from the Eocene.
Mantell, Medals of Creation, p. 256
Inset: The Fossil Forum

Brachiopoda (A-30)  = "Arm foot". Lampshells. Characteristics: 2 unequal shells, each bilaterally symmetric on the upper/lower surfaces in contrast to bivalve molluscs which have a left/right arrangement [Wiki].  They may be hinged at the top.  There are two major types: articuate and inarticulate. Most live attached to a surface and so are not particularly mobile. 

Classes (extant) [Wiki]: Craniata (formerly Craniforma), Lingulata,
Paterinata (?), Rhynchonellata.  Extinct classes: [ref: see table at] Sub-phylum Rhychonelliforma: Chileata, Obolellata, Kutorginata, Strophomenata.  The Lingulata have Calcium-phosphate shells, and the others have calcite (CaCO3) shells.

Class Lingulata. Calcium-phosphate/chitin shell. The Extinct genus Lingulella (Lingulids)  (Figure 26) was perhaps the most abundant fossil from the Lower Cambrian to Silurian (?).

Wolcott (1886) Cambrian Faunas, Plate 7
Figure 26
Class Lingulata
Walcott, Cambrian Fossils (1886), Pl 07

Class Craniata (= Craniforma). The Craniida ?? HOW TO IDENTIFY FROM FOSSIL EXAMPLES???

Class Rhynchonellata (former Articulata). The

Dana (1894) Silurian Rhynchonella p.548, 560
Figure 27
Class Rhynchonellata
Upper: Spirifer
Lower: Pentamerus, two species
Dana, Geology (1896), p. 548 & 560

Class Paterinata. The  ?????

Other extinct classes can be found in the fossil record.

Echinodermata (A-34) = "Spiny skin".  Characteristics: 5-fold radial symmetry + water vascular system. Classes: Asteroidea (sea stars, starfish, sea daisies), Ophiuroidea (brittle stars, basket stars), Echinoidea (sea urchins, sand dollars), Crinoidea (Sea lilies & feather stars), and Holothuroidea (sea cucumbers, holothurians).

Class Asteroidea
(sea stars, starfish, sea daisies).

Dana (1896) Ordovician Starfish
Figure 28
Ordovician Starfish
Class Asteroidea

Dana, Geology (1896), p. 510

Class Ophiuroidea
(brittle stars, basket stars).

Ramsay(1878) Silurian Brittle Star
Figure 29
Silurian Brittle Star
Protaster Miltoni
Class Ophiuroidea

Ramsay, Geology, p. 94

Class Echinoidea (sea urchins, sand dollars),

Agassiz (1839) Echnoidea Plate 18
Figure 30
Triassic Sea Urchin showing spines
Turban Echinus or Hemicidaris Crenularis Ag.
Top: Hemicidaris Alpina Ag.
Mantell, Medals of Creation (1844) p. 340
Agassiz, Echinodermes Fossiles (1840) p.144 & p. 152Pl. 18

Mantell, Medals of Creation (1844) p. 340

Class Crinoidea (Sea lilies & feather stars). The Oldest Crinoids date to the Ordovician [Wiki]. "In 2006, geologists isolated complex organic molecules from 350-million-year-old fossils of crinoids—the oldest such molecules yet found. Christina O'Malley, a doctoral student in earth sciences at The Ohio State University, found orange and yellow organic molecules inside the fossilized remains of several species of crinoids dating back to the Mississippian period."

Buckland (1837) Crinoids Plate 47 Plant History
Figure 31a
Carboniferous Stone Lilies
Class Crinoidea

Buckland, Geology (1837), pl. 47
Figure 31b
Ordovician Crinoid
Class Crinoidea

Dana,   Manual of Geology (1896), p. 505

Class Holothuroidea (sea cucumbers, holothurians). The fossil record of these worm-like animals is sparse [UCMP] because they are soft-bodied.  The earliest indications are spicules rather than bodies. See the Tree of Life page. for examples of fossil holothuroid ossicles.

Chordate (A-37) Subphylum Verebrata. Most Chordates are vertebrates. The term "vetebrae" means "to turn"  [Mantell, p. 588] and all vertebrates enclose the main nerve bundle in a bony column  consisting of vertebrae which are connected by flexible joints that  can bend and twist.

Fishes during the late Silurian and Devonian give the clearest early evidence of vertebrates. They constitute the first three classes: Agnatha (jawless fish -- the lampreys and hagfish); Chondrichthyes or Selachians (Cartilagenous jawed fish -- sharks and rays); and the Osteichthyes or bony fish. All of these classes thrived in the Devonian age (the "age of fishes") and their descendents thrive today. The Coelacanth perhaps holds the record for  longevity of a vertebrate order. The first fossil on record is a jaw dated to 360 Ma. It is from the class of bony fish (
Osteichthyes) with the characteeristic homocercal (symmetrical) tail.

Figure 32
Modern Coelacanth -- Latimeria
Discovered in 1938 off Madagascar

Extinct (sub-) Class Placoderma. This extinct class is sometimes considered a subclass of the Selachians because it has a cartilagenous skeleton.

The (primarily British Isles) Old Red Sandstone formation spans from the late Silurian, through the Devonian and into the early Carboniferous Ages. The formation was at first thought to be remarkably free of fossils, which were abundant both below (Silurian) and above (Carboniferous). The early geologist Hugh Miller discovered many remarkable fish fossils in this formation near to his home in Cromarty, Scotland, in the late 1820s. He described his work, written in his inimitable style in the book, Old Red Sandstone, originally published in 1842. The fish fossils from his book are from the extinct class of placoderms -- cartilagenous fish with heavy armor (Figure 33b).
The geologist Hugh Miller first discovered the Pterichthys (= "winged fish") in the Old Red Sandstone near to his home in Cromarty, Scotland16. It is notable for the "arms" that act as fins but are relatively inflexible. Some geologists consider them to be spines which normally lay along the side but extend out when the fish is alarmed.

Figure 33a
Selachians -- Placoderms
Class Chondrichthyes
Upper Devonian (365 Ma)
Dana p. 624

Figure 33b
Selachians -- Placoderms
Pterichthys oblongus Ag.
Class Chondrichthyes
Upper Devonian (365 Ma)
Miller, Old Red Sandstone (1858) Pl. I, II

Class Agnatha (Jawless Fish, no scales -- lampreys and hagfish). Ordovician   Cyclostomes  Ostracoderms ("shell-skinned") are any of several groups of extinct, primitive, jawless fishes that were covered in an armor of bony plates.  Ordovician, Silurian, and Devonian agnathans were armored with heavy bony-spiky plates. The first armored agnathans—the Ostracoderms, precursors to the bony fish

Class Chondrichthyes (= Selachians) (Cartilagenous jawed Fish, no Phosphate of Lime -- sharks and rays) Phosphate of lime is Ca3(PO4)2. An early fossil is shown in Figure 34. Note the typical heterocercal tail, which today is seen in sharks. Many of the earlier examples of these fish have teeth that are not embedded in the jaws.

Figure 34
Class Chondrichthyes (Selachian)
Miller, Old Red Sandstone (1858) Pl. IV

Class Osteichthyes (Bony Fish -- Contain  Phosphate of Lime) Probably the most famous "living fossil" from this class is the Coelacanth (figure 35). The oldest known fossil of a Coelacanth is a jaw found in Victoria, Australia and dated to the early Devonian, around 407-409 Ma17.

Jurassic Coelacanth (Wiki Commons)
Figure 35
Upper Jurassic Coelacanth
Undina penicillata
Class Osteichthyes

Class Amphibia (land/water -- gills and lungs; larval stage -- frogs, toads, salamanders). All of the non-fish classes of vertebrates have radially symmetric bodies with four limbs. Amphibians were the first vertebrate animals to move to land. The natural habitat of an amphibian is the shorelines of lakes, rivers and the oceans. All amphibians have a stage of life in which they live in water, and in fact they require a water medium for fertilization, which takes place outside of the body. One reason for this is that amphibia do not have an amniotic egg, as do the other non-fish classes.

Amphibians first appear in the fossil record in the mid-Devonian Age. In many instances the earliest indications of their existence is in tracks and footprints that they made in mudflats. In 2007, the New Mexico Museum of Natural History reported a
full-body impression of three salamanders (one of the three shown in Figure 36b) from the early Mississippian Age, about 330 Ma. This fossil impression had been collected many years earlier but not identified prior to this report. The earliest known fossil is from the Late Devonian of Scotland, about 38 My earlier (368 Ma)18.

Carboniferous-Dana-Amphibian Footprints Mississippian-Lucas-Salamanders body imprint
Figure 36a
Amphibian Footprints
Coal formation, Osage, KS
Dana p. 684
Figure 36b
Amphibian body imprint, length abt. 8"
Mississippian (330 Ma)
 Mauch Chunk, PA

Class Reptilia  (lungs; amniotic egg, internal fertilization. Lizards, dinosaurs).  The development of the amniotic egg, or more generally the amniotic sac, is one of the most important and remarkable inventions that permits animals to live and reproduce on dry land.

Lizards are reptiles and salamanders are amphibians. Reptiles have a rough dry skin, whereas salamanders have a soft moist skin. The first reptiles appear in the mid-Carboniferous era, about 340 Ma.

The crowning achievement of the reptiles is the invention of the amniotic egg.

Mesosaurs are the first aquatic reptiles -- perhaps the earliest amniote. Figure 37 is a mesosaur fossil embryo from the Lower Permian (280 Ma), the oldest fossil example of the birth (or perhaps miscarriage) of an amniote.
"Prior to the development of the amniotic egg, amphibians were "chained" to the ocean or some other large body of water, because they had to lay their eggs in water. If the eggs were removed from water and placed on land, they would simply dry out, obviously killing the egg." [Wiki] Thus reptiles were the first that could migrate to dry land for their entire life cycle.

Figure 37
Mesosaur Embryo
Lower Permian (280 Ma) - Uruguay
length of embryo about 1 cm.

Class Aves (wings; warm-blooded, feathers) Birds and mammals are warm-blooded. All other vertebrates are cold-blooded.

Archaeopteryx.  First feathers -- flight feathers.   Dinosaur or bird? See Wiki.  Late Jurassic, ca. 150 Ma. p788 Dana
birds have light-weight bones.
Figure 38
Late Jurassic (ca.  150 Ma)
Solnhofen Quarry, Germany (1861)
Note: The original fossil is here
Dana p. 788

Class Mammalia (mammary glands). The mammals are the vertebrates that are most familiar to us. The earliest to appear are the Marsupials (most of the development of the fetus occurs outside of the womb) followed by the Placentals (most of the development occurs in the womb). Mammals have dominated animal life since the C-T extinction event (65 Ma) which wiped out the dinosaurs and many other species.

Mammals are characterized by being warm-blooded, and possessing hair, three middle ear bones for balance and hearing
19], and mammary glands. [Ref: Wikipedia]. Red blood cells (lacking a nucleus) and a 4-chambered heart are also characteristics.

Mammals are divided into the following infraclasses, each of which involves major differences.

InfraClass Monotremata. Mammals that lay eggs

InfraClass Marsupialia. Mammals that give birth to undeveloped young (Kangaroos, opossum)

InfraClass Placentalia (Eutheria) Placental mammals that develop the young in the womb before giving birth. The oldest fossil of a placental animal is a shrew-like animal from the Jurassic Age, figure ??, announced in 2011.

 JuramaiaSinensis Oldest Placental mammal
Figure ??
Juramaia Sinensis
Oldest Placental Mammal
Jurassic (160 Ma)

Various "firsts" among the placental animals indicate how the modern mammals originated. Most of these fossils consist of individual bones and disarticulated fragments rather than complete specimens. See also Footnote 19 below.

Oldest Elephants and Mastodons.  Mastodons and Elephants have different types of molars. The oldest fossil Mastodon (family Mammutidae) is from the Congo, from the Eocene (40 Ma). The Mammoths are the oldest true elephants.   The ancestor of mammoths and elephants appeared in the late Miocene (7 Ma)22.

Oldest Whale. In 2011, the oldest whale fossil (bone) was reported. It was a jawbone from Australia, from the early Eocene, (49 Ma). This discovery poses some serious problems for the speed of evolution, because of the many anatomical changes needed to convert a land mammal into a whale. "There just isn't time."

Oldest Bat. The Oldest bat fossil, a perfectly preserved specimen, is from the Eocene (48 Ma) (Figure ??).

Eocene-Oldest Fossil Bat
Figure ??
Oldest Fossil Bat
Green River Formation, Wyoming
Eocene (48 Ma)

• Oldest Cats and Dogs21.  The Oldest cat (Proailurus, family Felidae) lived in the Oligocene, about 25 Ma.  A panther, dates from the Miocene, about 16 Ma. Wikipedia states that the line of cats and dogs separated in the Eocene (ca. 50 Ma).

The Oldest dog (Hesperocyon, family Canidae) fossil comes from Saskatchewan and is dated to the mid-Eocene (39.7 to 42.5 Ma).

• Oldest Primates. dddd.

47-million-year-old primate fossil unveiled Eocene (47 Ma). (not direct primate line!!!!)  (2009)



* The background is a fossil Coelacanth, one of the most ancient extant fishes (Figure *).  Long assumed to be extinct for over 65 million years, until specimens were discovered in South Africa off Madigascar by Marjorie Courtenay-Latimer in 1938. It is estimated that about 500 Coelacanths are alive today.

Figure *
Coelacanth fossil
Garden of Eaden

^n01 In analogy, the "body plan" of a house might include electricity, running water, flush toilets and central heat. Clearly this is of interest -- when did such a body plan first arise? -- but doesn't tell much about the changes in dwellings over the centuries.

^n02 There are several classification schemes in common use today, and more are undoubtedly coming in the future. Remarkable advances based on  Cladistic studies are happening almost daily because of the recent breakthrough of DNA sequencing techniques.

Cladistics is a somewhat different scheme of classification based on relatedness -- primarily inferrred by comparison at the level of genes and DNA sequencing.  Since the capacity to decode complete genomes was developed around the turn of the present century, this approach to classification has developed greatly, and holds promise for many new insights into implied genetic relationships at the very root.  "Although traditionally such cladograms were generated largely on the basis of morphological characters, genetic sequencing data and computational phylogenetics are now very commonly used in the generation of cladograms." [Wikipedia]

In the existing (perhaps now classical) classification schemes, the application of the terms "Class" and "Order" are sometimes interchangeable, and one often finds further divisions into other groupings: sub-phyla, super-orders, etc. On this website we generally follow the classification scheme of Lynn Margulis in Kingdoms and Domains.

For a list of all phyla, subphyla and  classes see the List of Animal Classes (the nomenclature differs somewhat from Margulis' used here). The Classes of Vertebrates carries the Class Vertebrata to the next level.

^n03 See Müller et al, Biochemistry and Cell Biology of Silica Formation in Sponges, Microsc. Res. Tech. 62:368 –377, 2003 and Silicateins, the major biosilica forming enzymes present in demosponges.


^n05  See

^n06  See

^n07 Jason A. Dunlop, Paleontology Online (2011)

^n08  GeoScience Online, 9 February 2011


^n10  The discovery of resilin was made by Torkel Weis-Fogh (Danish) in 1957. See Also see: and

Resilin has been found in pads of jumping (wingless) fleas. Jumping Fleas: Biomechanics behind a wingless existence. (Feb. 2011) - "Fleas, although wingless, retain several evolutionary features of the flight mechanism. Most significant of these features is the elastic pad that lies at the site where the legs attach to the body. This pad consists of a rubbery protein known as resilin, which in winged insects absorbs compressive force created during each wing stroke. The energy generated by this process is stored in the pad and is released to initiate each new wing stroke. In fleas, the resilin pads serve a similar function, but with the released energy being transferred to legs instead of wings."

^n11 The (remarkable) mechanics of insect flight: Carl R. Knospe, Insect Flight Mechanisms: Anatomy and Kinematics, (PDF) University of Virginia (1998)

^n12  North Carolina State University, Evolution and Diversity. Chapter 2, pg. 4 of John R. Meyer, General Entomology. "all [theories of wing evolution] fail to explain how or why such appendages acquired a hinge-joint mechanism, strong thoracic musculature, and the neural complexity necessary for sustained flight. appears that the ability to fly evolved only once in the class Insecta."  See also Insect Flight: Early Fossil Record: "The insect wing is not just a membrane that juts of the insect’s body. It’s a complex of membranes, veins, folds and flexures – looking at it laterally, it is in no way a simple two-dimensional structure. Even more mind-boggling is the wing base, with all sorts of sclerites as muscle attachment sites, plates, vein sources and the notal margin. It is to the wing base that all the power generated by the thoracic muscles goes, so it is also imperative to the way an insect flies."
Book of Insect Records  (U. Florida)

^n13  National Geographic News, The Oldest Lobster Fossil Found in Mexico (2007). The fossil is Palinurus palaceosi.

Also see


^n16  The fish was named Pterichthys oblongus by Louis Agassiz after Hugh Miller submitted it to him for identification. He writes about this in his book Old Red Sandstone. See the 7th Edition (1858), pg. 42ff, "an ichthyolite which the writer had the pleasure of introducing to the acquaintance of geologists nearly three years ago [1838 -- dcb]." He continues, "I fain wish I could communicate to the reader the feelings with which I contemplated my first-found specimen. It opened with a single blow of the hammer ; and there, on a ground of light-colored limestone, lay the effigy of a creature fashioned apparently out of jet, with a body covered with plates, two powerful looking arms, articulated at the shoulders, a head as entirely lost in the trunk as that of the ray or the sun-fish, and a long, angular tail. My first-formed idea regarding it was, that I had discovered a connecting link between the tortoise and the fish—the body much resembles that of a small turtle ; and why, I asked, if one formation gives us sauroid fishes, may not another give us chelonian ones ?"
^n17  A recent discovery of Eoactinistia foreyi reported in 2006 by Johanson et al, Biology Letters of the Royal Society, 21 February 2006.

^n18 Dana, p. 683    shows  a number of skeletal parts of amphibian fossils from Linton, Ohio.

^n19  Evolution of the Mammalian Middle Ear  See also the Wiki article, Evolution of Mammalian auditory ossicles. It would be interesting to know the gene package(s) needed to do this. For relationships among the Mammals based on genetic sequencing, see Paleontological Evidence to Date the Tree of Life Molecular Biology and Evolution Vol.24#1(26-53) (2006) for dating the divergences among Mammals.

^n20  "Discovery of "Oldest Fully Aquatic Whale" Fossil Throws a Major Bone into Whale Evolution Story" Evolution News, October 18, 2011.

^n21  Wiki. See also For a timeline see the Kentucky Gelogical Survey, Important Dates. For Family Candae see The Animal Diversity Web.  


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Paleobiology Database
Paleontological Evidence to Date the Tree of Life Molecular Biology and Evolution Vol.24#1(26-53) (2006)

Marine life:
Tree of Life Web project:
WoRMS = World Regiser of Marine Species
U.Michigan, Animal Diversity Web
Great Ordovician Biodiversification Event:
For a list of all phyla, subphyla and  classes see

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