That’s no beaver

Brian Thomas writes:

Researchers in 2006 described a fossil they named Castorocauda. They found it in a sedimentary layer mixed with pterosaurs, insects, amphibians, a dinosaur, and a gastropod. It “has a broad, flattened, partly scaly tail analogous to that of modern beavers.” Maybe it was a beaver.

(“Devils, Dinosaurs, and Squirrel Fossils,” January 2015 Acts & Facts)
That’s a common idea expressed by creationists – they don’t like the fact that the organisms alive in the past were different to those around today, so wouldn’t it be great if they were actually the same? Unfortunately for the creationists, these are testable claims.

Was it a beaver? The quote Thomas gives comes from the abstract of the paper he is referencing:

A docodontan mammaliaform from the Middle Jurassic of China possesses swimming and burrowing skeletal adaptations and some dental features for aquatic feeding. It is the most primitive taxon in the mammalian lineage known to have fur and has a broad, flattened, partly scaly tail analogous to that of modern beavers. We infer that docodontans were semiaquatic, convergent to the modern platypus and many Cenozoic placentals. This fossil demonstrates that some mammaliaforms, or proximal relatives to modern mammals, developed diverse locomotory and feeding adaptations and were ecomorphologically different from the majority of generalized small terrestrial Mesozoic mammalian insectivores.

The obvious red flag here – which should be clear even in Thomas’ paragraph – is that the tail is merely analogous to that of a beaver, and only the tail. This is an extraordinarily weak basis for declaring that Castorocauda lutrasimilis (this fossil) should actually be simply Castor lutrasimilis, i.e. a type of beaver. But this weakness isn’t enough on its own for us to say Thomas is wrong – that will require looking not at what the authors of the paper wrote but what they actually found.

Reconstruction of the lower jaw of Castorocauda lutrasimilis

Reconstruction of the lower jaw of Castorocauda lutrasimilis (full figure).

Jaws and teeth are great ways to distinguish between types of animals, and it just so happens that this fossil – which you can see a picture and reconstruction of here – includes them. As you can see the jaw is relatively straight and simple, as befitting a “primitive” mammal.

Rodent teeth and jaws

Rodent teeth

In stark contrast beavers are rodents, and rodent teeth are weird. You can find a picture specifically of a beaver skeleton here if you don’t believe me, but suffice to say that the skull of a Castor is very different to a Castorocauda.

Platypus dentition

Platypus dentition

While Thomas didn’t mention it – it would complicated his point – the authors also draw comparisons to the platypus, which is worth investigating. But it’s abundantly clear from the diagram above that the platypus too has very different teeth and jaws to the fossil.

So I think we can be extremely confident in saying “no, Brian, it’s not a beaver – and nor is it a platypus either, just in case that was your next thought.” We might also guess that Thomas didn’t do any of this research, contenting himself to making wild speculation without considering it important to test.

There are several other examples that Thomas gives in his article – the not-beaver is simply the most blatant. What do we make of this? Well for one, that the ICR and Brian Thomas are just as they always were. It’s good to be back.

6 thoughts on “That’s no beaver

  1. Just as bad. The “Tasmanian devil” and “giant ground hog”. Do these people really think that if something looks a bit like another animal it must, indeed, *be* that animal? What about this example?

    Nah, that’s one similarity they’ll *never* consider

  2. Another reason Thomas’s comments are misleading is that he notes that amphibians, insects and gastropods were found with the fossil, without clarifying that all of them were considerably different from modern members of those groups. Likewise, he like other YECs also fails to mention that not a single species of large modern mammal as ever been documented in any pre-Cenozoic sediments, whereas countless thousands should be if YECism were true. No where in the Mesozoic do we find any reliable evidence of any cat, dog, horse, hippo, rhino, whale, elephant, cow, deer, bear, etc, despite billions of fossils of dinosaurs and other prehistoric animals in these strata, and despite the fact that YECs claim they were all living at the same time when the great Flood occurred, and that most were buried during the Flood year only a few thousand years ago. Instead of facing the mountain of contrary evidence, they try to paint the opposite and demonstrably false picture; implying that we routinely find many modern species mixed up with prehistoric ones. For a group depicting themselves as upholders of holy truth, I find it despicable.

  3. @Glen. Another fun thing that these folks will claim is, that as there is some evidence of the earliest divergence of the basal Neognath bird lineages at the very end of the Cretaceous, that the dinosaurs were living alongside flamingos, parrots, ducks, etc.

    A master of this deception is Carl Werner. See my review of his book here (Evolution, the Grand Experiment: Volume 2, Living Fossils):

  4. BTW, Thomas has a similar article entitled “2014 Most Notable News: Fossils Resemble Living Relatives” on the ICR website. There he again exaggerates the similarities of various modern animals to fossil forms, while failing to reveal the astounding absence of any large modern mammal group in any Mesozoic and Paleozoic sediments, which thoroughly refutes their model. Likewise for the fossil record of plants. For example, we find no credible evidence of flowering plants anywhere in the Paleozoic or early Mesozoic, whereas by YEC models, there should be countless millions of angiosperm fossils and pollen fossils (since pollen grains are among the most readily fossilized structures, are ubiquitous in the atmosphere, and found by the zillions in Cenozoic strata). How could millions of flowering plants have been alive at the time of the Flood and pollen grains all over in the pre-Flood atmosphere and soils, and none be fossilized? None of their explanations for fossil succession (differential escape abilities, hydrologic sorting, or ecological zonation) even begins to explain this evidence.

  5. Speaking of 2014 developments, I wanted to mention that a recent issue of Acts and Facts reported that John Morris (who succeeded as president of ICR after his father died in 2006) had a stroke last fall, and is no longer serving as president as he focuses on his recovery (John is now considered President Emeritus). Has anyone heard how he is doing, or who the new president is? ICR’s website has a section entitled “About Us” but it does not list the board or staff members, and could not find this info anywhere else on the ICR website.


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