sted dd Mmmm 201?, Revised December, 2010


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

Chapter 9

The Fourth Genesis:

Creation of the First Animals*

ca. 540 Ma

"The Magnates Walk First"
Hugh Miller

"...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

"It is to fossils alone that must be attributed the birth of the theory of the earth; that, without them we could never have surmised that there were successive epochs in the formation of the globe, and a series of different operations. Indeed, they alone prove that the globe has not always had the same crust, by the certainty of the fact that they must have existed at the surface before they were buried in the depths where they are now found."
Baron Georges Cuvier, A Discourse on trhe Revolutions of the Surface of the Globe (1831)
On the "Importance of Fossils in Geology", p.  36.

NOTE:  See the page on body plans for a systematic summary of the animal phyla with early fossil examples. See the page on Body Algorithms for a discussion of the logic that is the basis of plant and animal body plans.

The creation narrative now turns to the creation of the first animals (this chapter) and plants (Chapter 10). This is done in several parts. This chapter considers the general rationale followed in creating the different animal body plans.

One important feature of this narrative is to observe the peculiar fossil evidence for Hugh Miller's remark above, which is continually reinforced as research advances: the conventional narrative of evolution of ever more advanced species misses the most basic facts of that narrative -- a failing that was noted during the early years of systematic studies of the fossil evidence, and which is reinforced today.  Indeed, a common feature found in the fossil evidence is evolutionary regression, from the more complex to the simpler and more specialized, rather than the reverse. Some examples of this regression are discussed below.

The Geologic Clock.  The history of the earth is recorded on a Geological Clock inscribed in the rocks (Figure 1). The early geologists of the 19th century were the first to recognize the vast amount of information about the Earth's past that these rocks yield, and the rough outlines of the record were already understood by the mid-1800s, although accurate age estimates had to await the discovery of radioactive dating methods in the early 20th century
01. That record continues to yield its recorded secrets up to the present time.
Geologic Clock from Wikipedia Geologic Clock from Wikipedia
Figure 1a
The Geologic Clock
Note: The times indicated are not fully settled, and may differ somewhat from
the times cited elsewhere on this website.
Figure 1b
Geologic Ages of the first plants and animals

The Fossil Record. The fossil record of visible plants and animals begins in the Cambrian Era, nominally dated to around 540 Ma02. The Cambrian era marks the beginning of the phanerozoic era -- literally, the age of visible animals. At the time that the Cambrian era was named by the geologist Adam Sedgwick, no visible fossils were known from lower formations. In recent times, some earlier multicellular fossils have been discovered in the immediately preceeding era, the Ediacaran Era, extending to about 600 Ma (Figure 1b), but this does not negate the principle conclusion that there was a time early in Earth history when no visible animals existed03.

All of the animals at this time lived in marine environments -- and this would continue until the ozone layer built up to filter out harmful cosmic rays which effectively sterilized the atmosphere and dry land. The first land plants and animals appeared once the ozone layer provided an effective filter against cosmic rays, at about 400 Ma. The fossil record after this date shows the progressive population of land, with plants and animals (especially insects) arising in a coordinated mutual development of pollinators and pollinatees.

The Earth's Fossil Record

The systematic correlation of fossils with the strata in which they exist was begun by William Smith in the late 1790s. By the early 1800s research was being conducted worldwide. Most of the present names for the fossil-bearing geological formations were coined by English geologists: Cambrian, Silurian (the "lower Silurian" was later renamed "Ordovician" -- see note 3), Devonian, etc.  The Cambrian formation was the oldest fossil-bearing formation, although it was recognized that microscopic fossils might be present in still older formations.

One of the most remarkable examples of the Silent Speech is the fossil record. As Baron Cuvier remarked in 1822: Continuing the quotation that heads this chapter:

"It is to fossils alone that must be attributed the birth of the theory of the earth; that, without them we could never have surmised that there were successive epochs in the formation of the globe, and a series of different operations. Indeed, they alone prove that the globe has not always had the same crust, by the certainty of the fact that they must have existed at the surface before they were buried in the depths where they are now found. It is only by analogy that we extend to primitive formations that conclusion which fossils enable us definitively to ascribe to secondary formations; and if there were only formations without fossils, no one could prove that these formations were not simultaneously produced. Again, it is to fossils, small as has been our acquaintance with them, that we owe the little knowledge we have attained respecting the nature of the revolutions of the globe. They have taught us, that the layers which comprise them have been undisturbedly deposited in a liquid; that their alterations have corresponded with those of the liquid; that their exposure was occasioned by the removal of this liquid; that these exposures have taken place more than once. None of these facts could have been decided on without these fossils."
Baron Georges Cuvier, A Discourse on the Revolutions of the Surface of the Globe, page 36.
See also David C. Bossard,  The Stones Cry Out, IBRI Research Report #57 (2006)

The existence of fossils in and by themselves, carefully preserved by the Creator over hundreds of millions -- even billions --  of years, have led to the certain understanding that the Earth is exceedingly ancient, and this fact was known decades before modern dating techniques were known. Only these fossils have made it possible to prove that the same uniquely identifiable plant and animal species co-existed in time all over the habitable parts of the earth.

Since that early recognition of the importance of fossils, modern advances in science have advanced the insights provided by fossils to an astonishing degree, leading to finer and finer calibration of the details of how life developed on Earth. The discovery of uncounted numbers of microscopic fossils, the refinement of multiple, overlapping radioactive dating techniques, the uncovering of rare but abundantly prolific remains of both hard and soft tissues of a broad range of species from the very beginning of multicellular life adds to the marvels of insight provided by these fossils.

This speech from the fossil record has revealed itself and made possible an understanding Earth's history in the distant past. This silent speech has proclaimed God's glory and handiwork for over 300 years, and the fruitful results contnue to arrive in an increasing crescendo right up to the present time.

See also the box
Fossils and the Geologic Ages

Multicellular Life.

Multicellular life arose about 1.5 Ga,
a few hundred million years after the creation of the proper cell (See the Second Genesis, Chapter 8). The time is not certain because of the lack of a good fossil record, and in any case the transition from single-celled to multi-celled eukaryotes is not clear-cut because colonies of single-celled creatures can assume some of the characteristics of multicellularity. Bacterial colonies have existed since the very earliest evidence of life, when cyanobacteria conspired to form stromatolites, many-layered formations that have existed for over 3 billion years (see the box below and Chapter 7, Figure 3).

Stromatolites -- the First Bacterial Colonies.

Fossils of cyanobacteria are the oldest fossils, dating to almost 3.5 Ba. Cyanobacteria are individual bacteria that form chains because the products of cell fission tend to remain attached. The bacteria secrete a thick gel or mucilage as protection against UV rays and with the result that the chains form into mats. Over many generations these mats build up multi-layered stromatolites (Figure 2). The stromatolites occur in tidal waters and the mats accumulate sand and other debris due to storms and wave action, resulting in the characteristic layered mineral build-up.

Stromatolites-Lester Park NY
Figure 2
Stromatolites (Cross-sections)
Lester Park, Catskills, NY
Bob Kopp (2008)

The stromatolite colonies exhibit a number of characteristics of multi-cellular life, even though they are made up of individual bacteria. The bacteria themselves specialize by forming heterocysts (specialized to fix nitrogen) and akinetes (specialized with a thick cell wall to survive under dessication and other harsh conditions). The production of food products and ATP are shared among the bacteria, particularly with the heterocysts which cannot produce all of their needs due to the energy demands of nitrogen fixing.

In the harsh early environment there was no ozone shield to filter out cosmic rays, which caused UV damage to bacteria exposed on the stromatolyte surfaces. However, these surface bacteria (living or dead) together with the accumulated surface debris, provided protection to layers just below the surface, so that the net result of the partial protection and rapid reproduction cause the bacteria to thrive.  There is also some evidence that the bacterial chains had a limited ability to migrate underneath protective surface layer to avoid direct exposure.

The stromatolite colonies also hosted other anoxic bacteria that could live along side of the cyanobacteria in the protectdion under the surface stromatolite layers

Full-fledged multicellularity had to await the creation of a proper cell, discussed in Chapter 8. With the proper cell came the microskeleton which gave strength and internal structure, much larger size, and an order of magnitude increase in the genetic material. This larger genetic resource gives the flexibility to support inter-cellular signalling, greater cell differentiation  and specialization.

The algae provide the simplest forms of genuine multicellularity  -- simple enough to cause a confusion in terminology: the name can include both eukaryotes and prokaryotes, although the present trend is to restrict the term to eukaryotes. For example, the cyanobacteria also go by the name "blue-green algae" although they are single-celled bacteria which happen to grow in chains.

There are four key features of true multicellularity

Specialization -- Division of Labor. The specialization of cyanobacteria into akinetes and heterocysts is an example of this.

Stigmergy -- "Meta-Collaboration". This term is recent, and it sometimes seems to be used in a mystical sense (which should be avoided, in my view). The idea is that the future development of a collection of cells is a function of its present state, but without implying that the change is actively controlled. The cells may belong to a single (multicellular) species, or they may be individual single-celled species acting in cooperation. One author calls it "unorganized actions" that stimulate other actions -- a group of individuals who collectively behave as a single entity. An example is the Slime Mold life cycle which is discussed further below. Another example is various kinds of damage repair. Stigmergy answers the question "what to do next" but without any overall overt direction. One author defines it as "emergent coordination in societies composed by a large amount of typically simple, ant-like, non-rational agents."

Signalling -- Polymorphic messaging. Polymorphic messaging means that the same signal (perhaps a chemical cue -- a Pheromone) may invoke different responses in different recipients. For example, in an ant colony, "Differently specialized ants, e.g., workers or defenders, respond differently to these chemical markers."
Apoptosis -- programmed cell death: remove cells that have outlived their usefulness.

Protist Colonies.
All protists -- single-celled eukaryotes -- live in water, or at least in moist environments (soils or tissues). Lynn Margulis places these species in the kingdom Protoctista -- see descriptions and the fossil record here. The plant-like protists are called protophyta (plant-like) and the animal-like protists are called protozoa (animal-like)09. Although they are single-celled, a given species may have more than one variant form -- such as the heterocysts and akinetes of cyanobacteria.

Many protists have complex life-cycles that include colonial phases. The life cycle of the slime molds (Margulis' phylum Rhizopoda, Pr-2) gives a fascinating example of something that seems half-way between a colony and a multi-celled animal (Figure 3)
10. At one stage of the life cycle, it is independent single-celled amoebas. At another stage the amoebas swarm to form a "slug". The slug looks and moves like a multi-cellular animal -- including a slimy cellulose "skin", but in fact each of the component amoebas retains its individual identity. In the reproductive stage the "slug" grows into a fruiting body -- a stalk with a round cap that bursts into a shower of spores that produce the next generation amoebas. At this point some of the original amoebas undergo programmed death to form the stalks and other specialized portions of the fruiting body. In the aggregated stages, the individual amoebas appear to use chemical signalling to initiate the various stages in the life cycle and coordinate the movements of the aggregation.

D discoideum life cycle
Figure 3
Slime Mold Life Cycle

True multi-cellular species. What is the difference between a colony of individual single-celled species and a multi-cellular plant or animal? Presumably the individual cells of multi-celled species cannot enjoy an independent existence. This situation was already seen in the heterocysts of cyanobacteria, which depend on sustenance from adjacent cyanobacteria. The cyanobacteria form heterocysts when they are facing a nitrogen deficiency. The nitrogen production is destroyed by oxygen which is a byproduct of photosynthesis, and so the heterocysts get the ATP and sugars produced by photosynthesis from adjacent cells. See also the Wikipedia article on the Evolution of multicellularity.

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

Margulis defines multicellular eukaryotes as members of one of the plants, animals, or fungi (three of the five kingdoms of life, the others being bacteria and protists -- single-celled eukaryotes). The single-celled eukaryotes, the protists (Margulis' protoctists) probably first arose on earth about the same time that oxygen became a stable component of the atmosphere and are the subject matter of the previous chapter, The Third Genesis.

The earliest multicellular fossils were animals, first appearing in marine environments, around 600 Ma. Plants, which are associated with land, arrived about 200 Ma later -- around 420 Ma. The delay in the arrival of plants is closely connected with the reduction in the harmful hard cosmic and solar radiation that came about when the high altitude ozone layer first built up to provide an effective filter against these rays. The gradual build-up of this ozone layer took over a billion years, counting from the time that the oxygen component of the atmosphere stabilized.

Evolutionary Adaptation. Before the arrival of plants and animals, bacteria changed their DNA by various means such as inheritance of radiation damage, genetic copying errors, horizontal gene transfer, and incorporating gene segments from food. Because of their high reproduction rates, beneficial changes could propagate rapidly through the local population.

With Eukaryotes, and particularly with multicellular species, the problems of complexity and the consequent reduced reproduction rates complicated the issues of adaptation because (advantageous) mutation of the sort that bacteria experience is very slow. The plants and animals solved this by the invention of sex; specifically, by the invention of meiosis, a new method of combining the genetic material from two parents to form offspring that combine the parents' genetic material but without enlarging the DNA (as happens with the bacterial methods of HGT and enphagation).

All species in the Plant, Animal and Fungus Kingdoms are capable of both sexual reproduction by meiosis as well as asexual reproduction by mitosis
(at least at the cellular level -- that is how they achieve multicellularity). One might view this as a way to get around the limitations of increased complexity that accompanies multicellular life, and might otherwise limit the potential for evolutionary adaptation. The ability of two successful organisms to combine bits of their genomes into an offspring produced variants with a much higher probability of success10.1.

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,but one would naively 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

See the box for further comment on how plants and animals are distinguished by Margulis and others. One basic difference is that plants tend to grow algorithmically and animals grow topologically. See further comment on this here.

Creation of the Animal Phyla in the Cambrian Explosion.

Since the beginnings of the systematic study of geological strata in the early 1800s, The Cambrian strata have been recognized as the oldest stratum in which visible fossils with hard body parts appear in the fossil record. Even with the astonishing discoveries of fossils in the Ediacaran Era which immediately precedes the Cambrian, the Cambrian still stands out as the era in which the animal phyla began. The remarkable fact about the Cambrian era is that all of the animal body types (phyla) appear here for the first time over a geologically short span of about 10 million years -- hence the Cambrian Explosion.

Animal fossils appear suddenly in the Cambrian Era, nominally 542 to 500 Ma with the nearly-simultaneous appearance of most if not all of the known animal body plans (phyla). With time, some early phyla disappear, but no new animal phylum arises after the Cambrian era, with the possible exception of Bryozoa

Coral reefs also appear at this time, the by-product of early soft-bodied cnidarians who secrete calcium that forms a hard habitat in which the coral individuals dwell (somewhat like the much earlier stromatolyte-forming cyanobacteria). Since the cnidarians are basically soft-bodied, it is not difficult to imagine that the coral ancestors were soft-bodied creatures that did not secrete calcium.

World Land Map during the Cambrian Era. The worldwide distribution of Cambrian fossils carries with it implications for how the continental landmass was configured during that Era (see Figures 7a-7c). Note that over this time the North American landmass moved from mid-Southern latitudes to equatorial latitudes. Note also the proximity of the future (emerging) Siberia, Greenland and North America, and the separation of these from South China (the location of the ChengJiang Ediacaran and Cambrian fossil beds).

Map-Early Cambrian Landmass
Figure 7a
Early Cambrian Landmass
544-511 Ma
Map Mid-Cambrian Landmass
Figure 7b
Mid-Cambrian Landmass
511-497 Ma
Map-Late Cambrian Landmass
Figure 7c
Early Ordovician Landmass
497-482 Ma

Continental Formation and Tectonic Movement

The Silent Speech of Psalm 19 includes an extensive record of how the Earth's landmass changed over the entire fossil record of life on earth. The description of this tectonic movement combines  a number of scientific disciplines, and involves extensive information preserved in a continuous record for over 500 million years. The website Dinodata shows this in one of the best collection of Early History Maps available on the Internet, The fact that scientists can form these maps of the distant past is a remarkable example of how God has invested his Creation with a silent speech that proclaims his glory and handiwork.

The Cambrian Explosion
. The Animal kingdom appears suddenly in the fossil record over 600 My ago, in what has come to be called the Cambrian explosion. The boundary that defines the start of the Cambrian age is the appearance of fossil burrows that were obviously made by a complex animal, probably an arthropod—the name means "jointed feet".

Cambrian Mollusc bivalve
Figure 8
Trichophycus fossil burrows
that define the start of the Cambrian age

The irony, from the perspective of natural evolution, is that all of the basic animal body plans appear almost simultaneously within about a 10 My span of time about 530 Ma.  A number of basic gene packages appear which were used over and over in many combinations during the subsequent development of animal life.  These are the hox genes, which control the development of many of the body systems, including eyes, appendages, and even body color patterns. These gene packages are highly conserved throughout the animal kingdom. For further information, see the discussion of hox genes.

From the viewpoint of evolution it is difficult to identify the origin of the hox gene packages. At least seven packages appear to be present in all animals (all radiata?), with additional ones present as in the more complex animals. These packages are highly conserved, so that widely different phyla -- for example, the insects and mammals -- have very similar sets of hox genes.

The Trilobites. The trilobites are the iconic symbol of the Cambrian era, and appear to have the full complement of hox genes (although of course the hox genes themselves have not been preserved in the fossils).

The Trilobites

Trilobites appear in the early Cambrian era, the oldest stratum of "visible" hard-shelled fossils (the Phanerozoic eon, beginning about 545 Ma). They first appear as complete, fully-developed arthropods. They are unique among the Arthropods in that the body plan consists of 3-lobed segments (hence the name), but otherwise they have features similar to modern Crustaceans.

One of the first and most complex animals to appear is the trilobite, an arthropod (joint-footed appendages), which by any reckoning must be viewed as a complex and morphologically advanced creature. This very complexity and sudden appearance suggests that the true origin was earlier than the fossil record indicates.
Perhaps trilobites are the most famous of the early fossils. They first show up as fully formed complex fossils -- without obvious ancestors discovered to date -- in the early Cambrian Era (521 Ma) and become extinct in the Permian Era (251 Ma) in a cataclysmic extinction that marks the end of the Palaeozoic Age, after about 300 million years. Thus the abundant and very long trilobite fossil record is an opportunity to observe the great range of species changes that can occur over a very long time14.00.

trilobite Early Cambrian
Figure 9
Early Cambrian Trilobite
See also Figure *

Evidence for Evolutionary Development. If one assumes that the observable changes in trilobite species over the 300 My of the fossil record amount to an extended example of Evo-Devo14.01 (which I do), then this long record gives a good opportunity to examine the implications of such potential for change, and is a good example of how the Silent Speech of Psalm 19 is woven into the natural world. Of course it is not possible to study this development at the genetic level on trilibotes themselves, but it should still be possible to reduce the observed changes into plausible hypotheses that can be tested in the laboratory using living species.

Recent work in Evo-Devo implies that most animal species -- extending back to the first appearance in the Cambrian era -- use a small packages of genes in the development of eyes and appendages (and, I suspect, many other major systems). These gene packages are virtually identical across a broad swath of species within and across many radically different body plans (phyla). From the viewpoint of investigation of these genes, all of the homeobox genes have the same leading sequence of amino acids, called the
homeodomain, so search for this sequence identifies the hox genes. Humans, for example, have 39 hox genes.

The differing end results are the result of homeobox (hox) gene expression, which follow instructions contained in portions of the DNA that do not code for genes. Apparently, the instructions are subject to some natural variation, and the variations can be passed to future generations. The beneficial (or neutral) variations tend over time to survive and the unbeneficial variations tend to die out. These give rise over time to different families, genera and species

A surprising conclusion of Evo-Devo work is that many animal features that appear to be quite different, in fact are at root different expressions of the same underlying gene packages: such as, for example, compound eyes and simple eyes, and even focusing and non-focusing eyes. The trilobites display a broad variety of eyes over their long history, and these appear (I assume) to be the accumulation of small variations in gene expression of the basic (and largely unchanging) gene package for eye development.
For example, at another place I argue that computer simulation might be able to investigate testable hypotheses that emulate the evolution of the trilobite eye from a conical shape (the holochroal eye) to the bi-layered elliptical or spherical shape (the schizochroal eye) -- a case, I believe, of paedomorphosis.

Life Cycle. Most trilobite fossils are trilobite molts. Trilobites molt repeatedly nearly from the time they hatch, which shows how they grow and mature. Thus the fossil record provides abundant documentation of the growth and molting process.

Soft-body parts. Normally, details of soft-body parts are not preserved in fossils. Discovery of pyritized trilobites provides another example of the Silent Speech. By a miraculous preservation, some trilobites discovered near Rome, New York (and a few other places globally) have had the hard and soft-body parts replaced by finely crystaline pyrite (FeS2) (commonly known as fool’s gold because of its golden color). They display finely detailed external appendages and gills. X-rays reveal details of soft tissue -- muscular, digestive, nervous and circulatory systems. As a result of this providential gift, much is known about trilobite anatomy despite the fact that they have been extinct for 250 million years (Figure 10)

trilobite anatomy
Figure 10
Trilobite Anatomy

Changes in morphology. Over the 300 My of existence many changes in the trilobites occurred. For example, the range of eye developments includes14.04:

• Number of compound eyes
• Location of eyes -- some eyes are located on stalks, others are crystalline and attached to the main epidermis
• Type of eye -- ranging from the schizochroal (unfocussed multi-lens eye) to holochroal (focussed single eye).

In addition, the mouth parts have undergone changes over time, reflecting the varying kinds of available food.

Systems. The trilobite has a full array of systems characteristic of advanced animals. These include:
appendages - jointed legs, claws, antennae (appear to be genetically controlled by similar gene package)
respiration - gills
vision - compound eyes (which change over time)
senses: vision, smell, touch, hearing?
muscular -
nervous - ganglia, primitive brain?
circulatory -
primitive digestive system - lack chewing parts, proper stomach, etc.

I believe the Creator left this extensive fossil record so that we could learn how much variation natural processes generate. As time passes, I believe that many details will be filled into the narrative. Already scientists are discovering something about the range of possibilities in the formation, location and type of eyes and the various appendages (antennae, legs).

It is useful to keep in mind that the distance between species may not be so close to appearance as might be thought. The maturation of a species is a complicated function of the gene pool and the gene expression (gene regulation). Laboratory experiments demonstrate that very small changes can result in radically different expression. For example, two trilobite species with radically different numbers of compound eyes (say, 500 or 5000) may not in fact be very far apart genetically: it boils down not to radically different genetic code, but to a difference in when the genetic expression was "turned off." An analogy would be in the difference between a faucet producing a cup of water and a bucket of water: we are not talking about radically different faucets, but just when the faucet was turned off. On the other hand, the difference between a cup of water and an ocean of water is probably a radical difference.

The Molluscs (A-26) and Brachiopods (A-30). Clams, oysters and scallops are molluscs: they are bivalves that hinge along the body axis. Brachiopods are also bi-valved, but hinge at the rear. According to Wikipedia, The Brachiopod 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." These fossils are very common throughout the geological ages, and are often used as index fossils to identify formations.

Sponges (A-3).

Cambrian Molluscs
Figure 11
Cambrian Sponge
Middle Cambrian

The Comb Jellies (
A-5). Some recent research suggests that Comb Jellies were the earliest animals, reported in the suggestive title Rethinking Early Evolution: Earth's Earliest Animal Ecosystem Was Complex And Included Sexual Reproduction (Science Daily March 20, 2008)15.

The page Body Plans gives a summary of other early examples of animal phyla that appear in the Cambrian Fossils.


Extinctions in the Fossil Record

There were a number of major extinctions of animal and plant life over the nearly 3.5 billion year fossil record.
Major extinctions:

450-440 Ma
Ordovician-Silurian extinction event
60% invertebrates
continental drift
to polar regions
2 bursts, 1 Ma apart
364 Ma
Devonian Extinction Extinction Event
Agnathan fishes,
19% familes,
50% genera
land not
Asteroid or comet?
(sea level, anoxia)

251.4 Ma
Permian-Triassic Extinction Event
"Permian-Triassic Boundary"
96% of
all species
70% of
fungal plague?
Animal extinction over 10-60ky.
Plant extinction over 100-300ky.
199.6 Ma
Triassic-Jurassic Extinction Event
50% species

climate change?
Volcanic activity?
within 10ky.
65.5 Ma
Cretaceous-Tertiary Extinction Event
K-T Extinction, K-T Boundary
Chicxulub Impact

In my view these extinctions were part of God's plan, and in effect "cleared the deck" for the subsequent creation.

Animal Body Systems
1. Regulatory
a. Body topography - orientation, symmetry, segmentation, etc.
b. Body parts -- appendages, defenses (stingers, claws, etc.)
c. Glands (skin) etc.
d. Life cycle
2. Digestion
a. Gastrovascular cavity -- one opening
b. Digestive tract (gut) -- two openings (mouth for food intake, coelom for digestion, anus for elimination)
3. Respiration - intake of oxygen, release of carbon dioxide
a. Diffusion across moist surfaces (earthworm)
b. Gills in aquatic animals
c. Lungs in terrestrial animals
4. Circulation - transport of oxygen and nutrients throughout the body
a. Open circulatory system -- some vessels; body cavity is "washed" with blood and lymph
b. Closed circulatory system -- blood enclosed in vessels, capillaries deliver to organs, recycled to heart.
5. Muscular
6. Nervous system -- coordinate activities of the body
a. Neurons -- nerve cells that send impulses
b. Nerve net -- network of neurons, very little coordination
c. Ganglia -- clusters of neurons (simple brain)
d. Brain -- sensory structures and neutrons located at anterior end, complex coordination and behavior.
7. Sensory systems -- (part of nervous system?)
a. Sight
b. Hearing
c. Smell
sensory pits
d. Taste
e. Feel/Touch
8. Support -- maintain body shape and support, aid in locomotion
a. Hydrostatic skeleton -- water pressure (jellyfish, worms)
b. Exoskeleton -- outside skeleton (insects, crabs)
c. Endoskeleton -- internal skeleton (vertebrates)
9. Reproductive (Genital)
a. Asexual -- reproduction of offspring from one parent. Offspring are idenical
(1). Regeneration -- fragmentation and regrowth (sponges)
(2). Budding -- growth and release of a clone (hydras)
(3). Parthenogenesis (rare) -- individual develops from unfertilized egg
b. Sexual -- reproduction by mating egg and sperm. One or two parents.
(1). Hermaphrodite -- single parent produces both egg and sperm (earthworm)
(2). External fertilization -- sperm and egg released into water.
(3). Internal fertilization -- sperm and egg mate within the female body.
10. Gestation
a. External (eggs, etc.)
b. Internal



Ediacaran Era --  google Ediacaran Fossils

trilobite internal anatomy:
• Before (visible) Animals ON LAND there were (visible) plants ON LAND. Hence Day 3 for plants, day 5 for animals. (?? Cf. 1851 Hitchcock, pg. 67)
"Thus the
Bible represents plants only to have been created on the third
day, and animals not till the fifth; and hence, at least, the
lower half of the fossiliferous rocks ought to contain nothing
but vegetables. Whereas, in fact, the lower half of these
rocks, all below the carboniferous, although abounding in arii
mals, contain scarcely any plants, and those in the lowest
strata, fucoids, or sea-weeds." p67

the role of fractals -- leaf design, tree shapes, etc. What this implies for algorithmic body plans.

On Anticipation

"We must suppose that when the Author of Nature creates an animal or plant, all the possible circumstances in which its descendants are destined to live are foreseen, and that an organization is conferred upon it which will enable the species to perpetuate itself and survive under all the varying circumstances to which it must be inevitably exposed."
Lyell, Principles of Geology (1850)
Ch. 35: Transmutation of Species, p. 560

"Why should the enlightened Christian, who has a correct idea of the firm foundation on which the Bible rests, fear that any disclosures of the arcana of nature should shake its authority or weaken its influence? Is not the God of revelation the God of nature also?"
Edward Hitchcock Religion of Geology (1851), p. 38

Contrary to both Darwinian gradualism and punctuated equilibria theory, the vast majority of phyla appear abruptly with low species diversity. The disparity of the higher taxa precedes the diversity of the lower taxa. --

An estimated 50 to 100 phyla appear explosively at the base of the Cambrian. Fossil evidence suggesting their common ancestry is not found in Precambrian rocks. A General Theory of Macrostasis is needed to explain the fossil data and the stability of the higher taxa.

Fossils and the Geologic Ages
The Phanerozoic Era

"It is to fossils alone that must be attributed the birth of the theory of the earth; that, without them we could never have surmised that there were successive epochs in the formation of the globe, and a series of different operations. Indeed, they alone prove that the globe has not always had the same crust, by the certainty of the fact that they must have existed at the surface before they were buried in the depths where they are now found."
Baron Georges Cuvier, A Discourse on trhe Revolutions of the Surface of the Globe (1831)
On the "Importance of Fossils in Geology", p.  36.

Fossils   Characteristic  of the Geologic Ages
From James D. Dana, Manual of Geology (1896)
pdf version (429 Mb)
Characteristic Fossils (from Dana)
Period (Wiki Ref.)
Timespan (modern determination)
01-Lower Cambrian Fossils Cambrian Era
542 ± 0.3 to 488.3 ± 1.7 Ma
02-Middle Cambrian Fossils

03-Upper Cambrian Fossils

04-Lower Silurian Fossils (Ordovician)
Ordovician Era
488.3 ± 1.7 to 443.7 ± 1.5 Ma
Odovician-Silurian Mass Extinction
440-450 Ma
Second Largest
05-Upper Silurian Fossils Silurian Era
443.7 ± 1.5 to 416.0 ± 1.5 Ma
06-Upper Silurian Fossils

07-Upper Silurian Fossils

08-Lower Devonian Fossils Devonian Era
416 ± 1.5 Ma to 359.2 ± 2.5 Ma
09-Middle Devonian Fossils

10-Upper Devonian Fossils

11-Upper Devonian Fossils

Late Devonian Extinction
360-375 Ma

12-Sub-Carboniferous Fossils Carboniferous Era
359.2 ± 2.5 Ma to 318.1 ± 1.3 Ma
13-Permian-Carboniferous Fossils Carboniferous Era
318.1 ± 1.3 Ma to 299.0 ± 0.8 Ma
14-Permian Fossils Permian Era
299.0 ± 0.8 Ma to 251.0 ± 0.4 Ma
15-Permian Subcarboniferous Fossils

Permian–Triassic extinction event
P-T Mass Extinction
251.0 ± 0.4 Ma
16-Triassic Fossils Triassic Era
251.0 ± 0.4 Ma to 199.6 ± 0.6 Ma
Triassic-Jurassic Extinction
     Conodonts disappear
T-J Extinction 199.6 ± 0.6 Ma
17-Jurassic Fossils Jurassic Era
199.6 ± 0.6 Ma to 145.5 ± 4.0 Ma
18-Triassic-Jurassic Fossils

19-Cretaceous Fossils Cretaceous Era
145.5 ± 4 Ma to 65.5 ± 0.3 Ma
20-Cretaceous Fossils

Cretaceous-Tertiary Extinction
K-T Boundary
65.5 ± 0.3 Ma
21-Eocene-Miocene Fossils Tertiary Era
65.5 ± 0.3 Ma to 2.6 ± ?? Ma
22-Pleistocene Fossils
Ends at end of last ice age
Pleistocene Era
Era of ice ages
2.588 ± 0.005 Ma to 11.7 Ka


Sharp Point          Origin of Body Plans: Hox genes

The puzzle of "Convergent Evolution" has been around since the beginnings of Evolutionary theory.  The puzzle is that  very similar features appear to have risen independently in widely diverse species. An example is the human eye (phylum Chordata) which is very similar to the octopus eye (phylum Mollusca). The answer, which is gradually emerging from the experimental science  evolutionary development, EvoDevo for short, is that the development of many if not all major organs and development structures (? right name?) is controlled by specific gene packages that were created in the Cambrian explosion, about 550 Ga, and which are essentially the same for huge swaths of animal types.

This observation does not, of course, explain how those packages arose in the first place.

From the viewpoint of EvoDevo, widely different morphologies occur by activating these development genes in different ways, not by creating new genes. Experiments which consist in manipulating the genetics to insert body parts in odd places has led to the identity of many of these gene packages.

Contrast with fractals (plants)

The Cambrian Fossil Record and the Origin of the Phyla

The Conodonts as time markers

Conodonts "teeth" are (until recently) the only fossil remains of this extinct worm-like creature. The name applies both to these bony structures and to the animal itself. They are plentiful, and amount to a trace fossil, appearing between the mid-Cambrian to the Triassic Era. In 1952 the first complete conodont fossil (from the Granton Shrimp Bed, Carboniferous Era) was described in 1963 by E.N.K. Clarkson.  Margulis calls the Conodont an early chordate class -- but not a vertebrate[
FOOTNOTE: K&D 261]. This is confirmed by some recent papers: see Conodonta: Overview at the Palaeos website. Other than these bony structures, the first full fossil was discovered by  in 1963.  Since the initial description, other complete specimens have been identified. The "switch" from phylum A-6 to A-37 was generally accepted around the turn of the (21st) Century.

Figure 12
Conodont Apparatus
Middle Ordovician
St. Peter Formation NE Iowa.
Huaibao P. Liu, et al. The Winneshiek Lagerstätte (2007)

The following figure is a reconstruction of a conodont (from the Palaeos website):

conodont skeleton
Carboniferous Conodont (1983)
Figure 13
Carboniferous Conodont Fossil

The conodont elements can be retrieved from limestone formations by dissolving the limestone in acid. The conodont elements remain and can be used as markers to calibrate the age of other fossils by "condodont zones" which can represent time intervals to within a small fraction of a million years -- more accurate than any other means of dating16  

Conodont "teeth": Precision fossil timepieces.
The soft-bodied conodonts lived between the Mid-Cambrian and the Permian Extinction (~520 Ma to 251 Ma). The characteristic feature of the Conodonts (and virtually the only fossil remains) were abundant microscopic "teeth"called Conodont elements, which apparently aided in breaking down food particles for digestion, and have microscopic sizes up to 0.5 mm.

These phosphatic "teeth" are liberally distributed in the fossil record over the 300 years of conodont existence, and can be used to calibrate fossil formations worldwide to within less than a million years. This is much greater accuracy than even the most precise dating with radioactive half-lives. The teeth vary their appearance slowly over time and have very distinctive shapes, so that specific micro-formations can be correlated worldwide, providing a precise way to date widely disperse formations, a fact that is widely used in the examination of drill core samples in petroleum exploration.

Conodont Elements
Figure 14
Conodont Elements


NOTE: However, a new convicing candidate for first chordate was announced in 1999 with Haikouichys -- an early (530 MYA) Cambrian fossil found in China.  These 2 to 3- cm  fossils resemble a tiny fish -- the first such animal in the fossil record (officially the first bony fish fossils are from the Ordovician Era).  Better specimens were announced in 2003 which show well-developed eyes, and other sensory structures characteristic of the cratiates, as well as the muscle blocks typical of early vertebrates  (Nature 421, pp 526-529).


  * The background is a mid-Cambrian trilobite (about 530 Ma), see Figure 15.

Mid Cambrian Trilobite
Figure 15
Mid Cambrian Trilobite
Paradoxides, length 10"
Braintree, Mass.
Trilobites are the prototypical symbol of the
Age of Fossils.

Hugh Miller, Foot-prints of the Creator, (3rd. Edition, 1858) p. 325. The full quote is:

"We know, further, so far at least as we have yet succeeded in deciphering the record, -- that the several dynasties were introduced, not in their lower, but in their higher forms; that, in short, in the imposing programme of creation it was arranged, as a general rule, that in each of the great divisions of the procession the magnates should walk first."
sharp point
The Magnates Walk First

This expresses a great sharp point: that in the course of creation, the earliest members of a race are not the simplest but tend to be the most complex, in Hugh Miller's words, the "magnates", with simplification and specialization, rather than its opposite, occurring with the passage of time. This is a theme that recurs many times throughout the creation narrative.

Note: See also Chapter 8, Reductive Evolution and footnote 1.5.
The following quotations are from James D. Dana, Manual of Geology (1896). Discoveries since that time have only sharpened his observations.

"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."
p. 487

"We must suppose that when the Author of Nature creates an animal or plant, all the possible circumstances in which its descendants are destined to live are foreseen, and that an organization is conferred upon it which will enable the species to perpetuate itself and survive under all the varying circumstances to which it must be inevitably exposed." p. 560

"Principles of Biological Change and Progress for Animals: Outline (somewhat edited), p. 716-718
    1. From the simple, regular, or primitive in structure to the specialized.
        a. From a structure with two or more functions to organs, each with its specialized function.
        b. From a single-function organ has several uses, to special forms for each kind of use.
        c. From simpler forms of specialization to more complex, better adapted forms.
        d. From any specialized form to others adapted to newly acquired uses
        e. From a head with large sense-organs and mouth-organs to one with smaller and well-compacted organs.
        f, From large aquatic structures to smaller terrestrial structures.
    2. Approximate parallelism between geological succession of structures and embryological succession in development.
    3. Degeneration: a. Of an organ to a more primitive form; b. diminished size or disappearance of an organ; production of low-grade structures that have needed form and activity
    4. From diffuse to concentrated structures.
       a. From elongated to abbreviated; b. From multiple, indefinite number of segments, to limited numbers and arrangement; c. From posterior locomotive organ to anterior locomotive organ; d. From stronger posterior limbs (merosthenic) to stronger anterior limbs (prosthenic)."

Other early geologists expressed this same thesis: Edward Hitchcock, The Religion of Geology (1851), p.256, quotes Adam Sedgwick, Discourse on the Studies of the University, 5th Ed, (1850). p. lxiv. as follows:

"All our most ancient fossil fishes belong to a high organic type; and the very oldest species that are well determined fall naturally into an order of fishes which Owen and Müller place, not at the bottom, but at the top of the whole class." Sedgwick continues: "Fishes of the very highest organic type existed during the period of some of our old Palaeozoic strata; and no Fishes of an inferior organic grade have been found below them."
Adam Sedgwick, in a critique
Vestiges by Robert Chambers
As far as I am aware, this situation largely continues to the present day: See the footnote on the Comb Jellies. See the box on Reductive Evolution. Louis Agassiz in his Natural History used the term "prophetic types" (see Vol I., p. 116 ff) for Miller's "magnates".

^n01  Over 100 geology books from this era are posted at the Golden Age of Geology website.

^n02 The actual beginning of the Cambrian Era is determined by the International Subcommission on Cambrian Stratigraphy. In 1991 they set the Cambrian boundary at the first appearance of fossil burrows known as Treptichnus pedum, that were obviously made by a complex animal, probably an arthropod, dated to 590 Ma. Since that time the date has been moved to a later time; it is still under discussion. See the lecture, David C. Bossard Abundant Life. The modern priapulid worms produce a similar, complex fan-like or twisted rope-like burrows (Figure 16). See also an informative article in Fossil News: Lynne M. Clos The Cambrian in North America (2004).

priapulid worm Ottoia
Figure 16
Priapulid Worm in burrow.

^n03  The International Union of Geological Sciences accepted the Ediacaran as an official geological period in 2004. It was the first new geological period named since 1879, when the Silurian period was divided into two periods: Ordovician (previously the Lower Silurian) and Silurian periods. See characteristic fossils of the Ordovician Era in Dana, Manual of Geology (1896). See also The History of the Geological Society of London (1907), Chapter IX, "The Cambro-Silurian Controversy."

^n04  For further discussion of cyanobacteria see the article First Life. Although stromatolite colonies are rare today, cyanobacteria are found in many places, such as in the bright green "Algal blooms." Cyanobacteria produce many cyanotoxins and so their presence in red tides and other  places can be toxic.

^n06  See The Evolution of Multicellularity. See also  NIH, From Single Cells to Multicellular Organisms.

^n07 Alessndro Ricci et al, Cognitive stigmergy: towards a framework based on agents and artifacts (2006).

^n08 Messaging in Biology.

^n09  Margulis, Kingdoms and Domains, p.122.

^n10 The Rhizopod D. discoideum, ibid., Fig. F, p. 137 (also available here.). Research on this species is proceeding in a number of areas: cellular differentiation, signaling, programmed cell death, etc. because of its short life cycle (8-10 hrs).  The DNA has been completely sequenced.

^n10.1 "
The ability of two successful organisms to combine bits of their genomes into an offspring produced variants with a much higher probability of success. Those moves in the search space are more likely to produce an advantageous variation than random ones. The advent of sex dramatically changed the course of evolution. The new mechanism for the generation of variation focused nature’s search through the space of possible genomes, leading to an increase in the proportion of advantageous variations, and an increase in the rate of evolutionary change." Lawrence Hunter, Molecular Biology for Computer Scientists pg. 9 , pdf version

^n11  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.

^n11.1  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.

^n11.2  See the 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 developmenr [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.

^n11.3 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).

^n11.4  Cellulose has been called "the most common organic compound on Earth," and lignin is the second most common.

^n11.5  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."

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

^n14.00 For illustration of the changes, see S.M. Gon III, Evolutionary Trends in Trilobites. Some paleobiologists argue that the real innovation in the Cambrian era was hard skeletal parts which the fossil record preserves; prior to this innovation, the same species existed in soft bodies that were not preserved. Until positive evidence arises to support this (such as soft-bodied trilobites) this seems to be a case of special pleading in the absence of evidence. Regarding this, the Cambrian Factsheet (Discovery Institute) remarks: "Some scientists have suggested that fossil ancestors for the animal phyla are missing not because the rocks have been deformed or eroded, but because animals before the Cambrian lacked hard parts, and thus never fossilized in the first place. According to this hypothesis, the Cambrian explosion merely represents the sudden appearance of shells and skeletons in animals that had evolved long before. The fossil evidence, however, does not support this hypothesis.

Evo-Devo attributes evolutionary change to changes in gene expression of a limited number of highly conserved genes. The gene expression is controlled by homeobox (hox genes (also conserved, although not so highly as the gene packages) combined with development parameters that are recorded in the portions of DNA that do not code for genes.

The use of DNA profiling to identify individuals is based on variations between individuals in non-coding portions (so-called "junk" dna).

Rolf Ludvigsen, Fossils of Ontario Part 1: the Trilobites, Royal Ontario Museum, 1979, pg. 22. Also see various internet discussions of pyritized trilobites.

^n14.04  The trilobite eye is described and illustrated in David C. Bossard Abundant Life.

^n15  See Body Plans. This article speculates that sponges are actually a product of reductive evolution from the comb jellies, in which the sponge phylum represents a loss of features originally present in the comb jellies.

^n16 The use of conodonts in petroleum surveys: "The petroleum industry uses conodonts as indicators of the degree of maturation of hydrocarbons in sedimentary basins as well as for biostratigraphy. Unburied and unheated conodonts have a light amber color because they retain complex organic molecules in the skeletal framework. When conodonts undergo deep burial and heating, these organic molecules change or mature in the same manner as do organic substances in the strata that are transformed into oil and natural gas. As the organics in the conodonts mature, the conodonts change color from light amber to dark amber to brown until they turn black. Experimental work and field research shows that when conodonts are light brown, the sediments have been buried and heated to a degree such that hydrocarbons have fully matured into oil". See also  W. Britt Leatham, The Hidden World of the Conodonta and  Conodonta Overview.].

17   ^n17  n

18   ^n18  n

19   ^n19  n

^n20  Lyell Collection, citing Runnegar & Pojeta (1974). Scaphopoda may date from the mid-Ordovician Era.]


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

Microscope Image Gallery.

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.

Wikipedia Articles:  Animals,

Web sites

Web Geological Time Machine (Berkeley U)


mailbox Any comments or suggestions are welcome. Please email:



Posted dd Mmmm 201?