Why Such Large Animals in the Fossil Record?

If size is a measure of evolutionary progress, things seem to have gone downhill since many fossils were deposited.

Super salamander: A salamander as big as a car? That’s what was reported by the BBC News, Science Magazine and other news sites. Multiple fossils of Metoposaurus algarvensis were found in a bone bed in Portugal. The two-meter-long creature, squat looking with a flattened head and lots of teeth, is said to have lived before the dinosaurs and was the apex predator of its day. “Similar bone beds that include other species of metoposaurs have been found in what are now Africa, Europe, and North America,” Science Magazine says. This monster is said to be the ancestor of the little hand-sized salamanders we have today.

Croc of the Walk: A 9-foot crocodile that walked on its hind legs was reported by North Carolina State University News.  Said to be the “top predator of its day” and a “crocodile ancestor,” this “crocodylomorph” looks pretty scary from the artist’s rendition.  The “Carolina butcher” was larger and more mobile than its alleged evolutionary descendants. “We knew that there were too many top performers on the proverbial stage in the Late Triassic,” a paleontologist says.

It’s obvious that many dinosaurs were much larger than any reptiles on earth today.  We still have the world’s largest animal of all time (the blue whale), the world’s largest plant (the giant sequoia) and other sizable creatures around (giraffes, grizzly bears), but most living organisms are smaller than their fossil representatives. The fossil record shows numerous gigantic creatures: dragonflies with 2-foot wing spans, huge butterflies, giant tree ferns, extinct “sea serpents” (ichthyosaurs and plesiosaurs), the largest flyers ever (giraffe-size pterosaurs), wooly mammoths and other mastodons, giant cave bears, giant sloths, large lions and saber-tooth tigers, large camels and bison (e.g., in the La Brea Tar Pits), and other champions when it comes to size.  If size matters to evolution, it’s been largely downhill since these fossils creatures lived.

An evolutionary law?: One of the few “laws” of evolution is supposed to be “Cope’s Rule” that proposes animal bodies get bigger over time. It works for some groups, but not for those mentioned above. Recently, Stanford researchers said Cope’s rule works for some marine phyla: Arthropods, Brachiopods, Chordates, Echinoderms, and Mollusks (Science Daily; paper in Science Magazine).

Scientists have attempted to test Cope’s rule in other animal groups, but the conclusions have been mixed. Corals and dinosaurs seem to follow Cope’s rule, for example, but birds and insects do not. As a result, some scientists have wondered whether the pattern observed in land mammals is a real evolutionary phenomenon or merely a statistical one resulting from random, non-selective evolution, also known as neutral drift. “It’s possible that as evolution proceeds, there really is no preference for being larger or smaller,” said Noel Heim, a postdoctoral researcher in Payne’s lab. “What appears to be an increase in average body size may be due to neutral drift.”

The authors claim that they verified Cope’s Rule for the marine phyla they studied, but it appears to be a variation on the old rule: “not all classes—groups of related species and genera—of animals trended toward larger size, but those that were bigger tended to become more diverse over time,” they say. They did not address the land animals that have shrunk in size over time. The obvious conclusion seems to be that Cope’s Rule works except when it doesn’t (see Stuff Happens Law).  The paucity of large creatures alive today, and the predictive mushiness of Cope’s Rule, do not bode well for the explanatory value of Darwinism.

On the small scale: National Geographic posted an interesting gallery of the world’s smallest animals, from cells to mammals. Featured are the smallest living cell, mouse lemurs, miniature horses smaller than a large dog, dwarf sharks, the bumblebee bat, and a pygmy butterfly. Miniaturization is thus seen all over the animal kingdom. It should be remembered that every animal starts out tiny, as a one-celled zygote.

Proportionality constant: How does an animal get its legs to match its body, or the head to be the right size as the embryo grows? A mouse-sized head on a T. rex would be a problem. Or what if a human grew the wrong size liver? How body proportions are regulated is a big question, Science Daily reports:

“One of the most intriguing questions in animal development is something called scaling, or the proportionality of different body parts,” said Jun Ma, PhD, senior author and a scientist in the divisions of Biomedical Informatics and Developmental Biology. “Whether you have an elephant or a mouse, for some reason their organ and tissue sizes are generally proportional to the overall size of the body. We want to understand how you get this proportionality.”

To try to answer these questions, researchers in Cincinnati examined levels of gene expression in fruit flies as they developed. They didn’t get answers; only more questions. “This finding leaves the researchers with new questions to unravel, such as its fundamental meaning, and how much the relationship between a mother’s biological investment and the way her embryos develop is impacted by the larger principles of evolution.” Darwinism hasn’t helped so far, in other words.

Epigenetics and size: Scientists at McGill University say that it may not take much to make an animal bigger. By experimenting with ants, they found that epigenetic factors operating on a single gene can cause a cascade of effects, making the insects bigger or smaller without a genetic change.  This is a profound conclusion, they say:

“It’s a discovery that completely changes our understanding of how human variation comes to be,” says Abouheif. “So many human traits, whether they are intelligence, height, or vulnerability to diseases such as cancer, exist along a continuum. If, as we believe, this epigenetic mechanism applies to a key gene in each area, the change is so enormous that it’s hard to even imagine right now how it will influence research in everything from health to cognitive development to farming.”

What this implies is that environmental cues can make a big difference in the size of creatures without modifying the genetic code.

With a stronger magnetic field and a different atmosphere, antediluvian animals could have grown larger and more robust. Conditions changed after the Flood, leaving our world impoverished compared to its original diversity, but still a wondrous display of God’s creative ability.