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Beaver-like mammal from the middle Jurassic of China

The given name, Castorocauda lutrasimilis means that it had a beaver like tail and therefore also similar to the otter. (castor = beaver, cauda = tail, lutra = otter). The given order of Docodonta is claimed to be a wholly extinct group of mammaliaformes that were the forerunners of modern mammals, as opposed to modern orders of mammals that include the monotremes, the placental mammals and the marsupials. The Monotreme group refers to egg-laying mammals such as the duck-billed platypus. Creationists accept that some orders or species have become extinct, but there is no reason to suppose that modern mammals were not also present before the Flood in this period. Such mammals must have included the dog, cat, beaver and otter kinds, but until now there has been a shortage of fossils. Most finds were in the form of teeth with the rest of the animal missing. However, the layers from China have proved a rich hunting ground for palaeontologists because of the remarkable degree of preservation. Other evidence has shown that the layers of China have provided fossils that contradict the prevailing biostratigraphic evolutionary assumptions. Triassic and late Cretaceous dinosaurs have been identified in the same Jehol Group layers for instance. Such finds are challenging currently accepted theories of evolutionary progression. See for instance: The truth about the Chinese fossils from Liaoning Province

Castorocauda lutrasimilis was found with a remarkable degree of preservation, which includes hair and skin together with auditory ossicles of the middle ear, and the appearance of webbing between the toes. The tail was remarkably like that of an otter or beaver with scaly skin interspersed with matted hair. The degree of preservation indicates also that the animal had two layers of hair, one inner layer to ensure the skin stayed dry under water as is the case with other aquatic mammals known from today, with also a longer thicker outer guard layer. The limbs are shaped in similar fashion to the platypus suggesting that it used them for digging, while the teeth suggest a fish eating diet. Although identified as Decodonta, (the order Docodonta gets its name from the shape of teeth) this animal’s teeth were similar to those of the present day seal.

The claimed age of Castorocauda lutrasimilis is given as 164 Myr and therefore assigned an age in the middle Jurassic period. Bearing in mind the features, this is a real surprise to evolutionists who previously believed that the only mammals in the Jurassic were small rodent types. Another mammal, given the name Repenomamus giganticus with order Triconodonta, was found in the early Cretaceous Yixian layers of northeast China with claimed dating around 128 Myr. This animal that in some sense was like a badger was over one metre in length. Again the size has challenged current evolutionary hypotheses, and it was found with the remains of the small theropod Psittacosaurus in its stomach, indicating that mammals were further up the food chain than previously thought.

Summary

Once again the fossil layers of China are throwing the evolutionary paradigm into chaos with mammals very similar to modern forms popping up in deeper layers than previously thought possible. As creationists we believe that this is only to be expected, that although some species have become extinct, the direct ancestors of modern animal kinds must have been present on the pre-Flood period. Although palaeontologists have placed these animals in different orders than modern mammals, the degree of similarity suggests that this different classification is driven more by the dogma of evolution rather than major differences in form between the animals.

References

Ji, Q., Z.-X. Luo, C.-X. Yuan, A. R. Tabrum. February 24, 2006. "A swimming mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals". Science, 311:5764 pp.1123-1127

Yaoming Hu, Jin Meng, Yuanqing Wang, Chuankui Li. 2005. Large Mesozoic mammals fed on young dinosaurs. Nature, 433: 149–152

This message was added on Wednesday 20th September 2006