Re: The fossil record

From: David Campbell <pleuronaia@gmail.com>
Date: Thu Feb 02 2006 - 19:17:10 EST

>
> The Nature of the Fossil Record
> "95% of the fossils (by number) consist of shallow marine organisms
> (e.g., corals, shellfish).
> "Of the remaining 5%, 95% are all the algae and plant/tree fossils
> (including the coal) and all the other invertebrate fossils (e.g.,
> insects).
> "5% of the 5% (or 0.25% of the entire fossil record) are the vertebrate
> fossils (fish, amphibians, reptiles, birds and mammals).
> "Only 1% of this 0.25% (or 0.0025% of the entire fossil record) are
> vertebrate fossils that consist of more than a single bone! (E.g., there
> are only about 2,100 dinosaur skeletons in all the world's museums.)"
>
> Kurt Wise, "The Nature of the Fossil Record," ICR lecture.
>
> Are the quantifications above approximately true?
>
> Just wondering. Not that they prove anything.

As Don pointed out, the vast majority of fossils are of microorganisms,
mostly planktonic microscopic algae (only because preservation of fossil
bacteria is rather sporadic as far as I know, whereas many of the algae have
hard or tough skeletons). Pollen would also be a large chunk numerically.

Shallow marine settings are the best represented ones in the accessible
fossil record, though deep marine settings are probably the best represented
in the actual global record (most of which is under deep oceans).

Oceans represent over 70% of the earth's surface, there was little life on
land before the early middle Paleozoic, and land is eroding and the
resulting sediment piling up under water, all of which contribute to a
greater abundance of marine fossils than terrestrial. Invertebrates are
vastly more abundant than vertebrates, and plants and algae are vastly more
abundant in terms of mass than invertebrates-the laws of thermodynamics
dictate that there's less than 100% efficiency in getting energy out of your
food, so the bottom of the food chain has the highest total abundance.

Fossil insects can be very abundant in the right setting, so the percentage
given for them may be a bit low, especially if one counts small bits and
pieces.

Vertebrates do tend to fall apart after death (one advantage of studying
mollusks, most of which have only one or two shells!). On the other hand,
bones are relatively large and durable compared to most remains. By total
abundance, one of the most common vetebrate fossil type is shark teeth.
They continually grow new teeth and lose old ones, so one shark may go
through several thousand teeth in its lifetime but only one skeleton.
Teeth, with their enamel, are extra durable, whereas shark skeletons are
mostly cartilage and are rarely preserved. Many other vertebrates go
through several sets of teeth, contributing to the nuber of single pieces
out there.

Associated vertebrate fossils are indeed rare out of the total number of
fossils, though they can be very common in the right setting. I don't think
I've personally discovered any, though the fact that I've been looking for
mollusks has something to do with that. However, I have helped excavate a
set of reptile skeletons discovered by a student and have visited some of
the classic dinosaur skeleton localities.

I suspect that the dino skeleton count may be a bit low by now, though not
off by an order of magnitude (disregarding those who would claim that all
the bird skeletons in museums are dinosaur skeletons, which has some
evolutionary validity at the expense of confusing the average person). On
the other hand, there are millions of fish skeletons in the Green River
Formation in the central Rockies region.

Not sure how trace fossils (footprints, burrows, etc.) fit into his
categories.

> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"
Received on Thu Feb 2 19:17:40 2006

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