Wednesday, November 6, 2013

Nests of strange dinosaurs

Illustration of a group of nesting therizinosaurs.
Credit: Masato Hattori.  Image Source.
Last week at the annual meeting of the Society of Vertebrate Paleontology, Japanese paleontologist Yoshitsugu Kobayashi presented his findings of a dinosaur nesting ground in the Gobi Desert of Mongolia.  Unfortunately, I was not present at the conference, so I can only go by a summary of the talk posted by LiveScience.

No embryos were found inside the eggshells, but several sites near the nests yielded the remains of therizinosaurs, so the eggs were attributed to them.  Therizinosaurs are a very odd group of dinosaurs.  They are classified as maniraptoran theropods, a group primarily composed of small, quick predators, such as Velociraptor  and Deinonychus, as well as birds.  Like their relatives, therizinosaurs exhibit long arms, large claws on their hands and feet, and a somewhat ostrich-like form.  Strangely, however, they appear to be herbivores, due to the structure and shape of their teeth and "beak."  It is postulated that their long arms and claws were useful for pulling and cutting branches from trees.

The LiveScience article does not discuss any geological information, so I do not know the exact evolutionary explanation for the burial of the nests and their nearby architects.  I can say that these sorts of sites are usually attributed to large sandstorms or flash floods.  The lack of embryos and presence of eggshell bits inside of the eggs led the scientists to claim that the eggs must have hatched before they were buried.  Personally, I find this claim somewhat dubious.  A brood of newly hatched animals will normally crush the remains of the eggs, rather than leaving them partially intact and round as these were found.  Additionally, I have not come across any mention of juveniles near the nests or with the adults nearby.

The creationist model, of course, presents a different picture of what occurred at this site.  Although the Bible confirms that Noah's Flood covered the entire earth, it is not necessary to presume that the entire earth was covered at the same time.  Nesting grounds like these support this, as it would be difficult to make a nest and lay eggs under water.  Instead, it may be that this area was flooded periodically during the flood year, depositing large amounts of sediment, followed by brief dry spells.  During these dry spells, dinosaurs like the therizinosaurs would frantically search for a spot to lay their eggs.  Like modern birds, therizinosaurs likely developed and laid eggs regardless of fertilization.  If the Flood interrupted their mating season, the therizinosaurs would have carried unfertilized eggs during the stressful first few months of the Flood.  As soon as they had an opportunity to congregate and lay the eggs, they did so, resulting in numerous nests of unfertilized eggs.  The Flood continued, burying and breaking, but not completely crushing, the eggs in more sediment.  It can easily be imagined that the egg-layers were buried a short distance away while trying to escape the next wave of disaster.

Although the Bible does not give specifics on the mechanics of the Flood, the geologic and fossil records seem to show that it was a complex catastrophic event, not a simple case of "waters rose, waters fell."  Such a model does not at all contradict the biblical narrative.  Even naturalistic interpretations are more frequently relying on catastrophic flooding to explain many sediment and fossil deposits.  However, we cannot presume that the two camps are headed toward an agreement.  Though the evolutionary model may not persist in its current form, a naturalistic explanation will always be sought for the origins of life and the universe, lest they be attributed to an infinite, just, all-knowing, all-powerful Creator.

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