Sunday, April 14, 2013

Dinosaurs of the Gobi Desert

The Osaka Museum of Natural History is currently showing an exhibit of fossils from the Gobi desert.  Until June 2nd, 2013. Fossils from this area have been revolutionary in regards to the evolution of birds and our understanding of when and feathers evolved.
Several species were well represented including: Protoceratops andrewsi, Velociraptor mongoliensis, Tarbosaurus bataar, Saurolophus angustirostris, Ankylosaurus and others.

An incredibly well preserved nest of Protoceratops andrewsi hatchlings showing that they stayed in the nest for at least a little while after hatching.


Reconstruction of an adult P. andrewsi
Reconstruction of a juvenile P. andrewsi 
 
Skull of Saurolophus augustirostris a large hadrosaur.
 Articulated skeleton of S. augustirostris

Ankylosaurus must be one of the easier dinosaurs to imagine what it was like when it was walking around.
 
Even the largest of dinosaurs had eggs that were the size of ostrich eggs, limited by the physics of transporting enough oxygen through the shell and having the shell be strong enough to not collapse. 

Fossilized crocodile hatchlings haven't changed much. though some species of extinct crocodilians were very different from the species that are extant today.
 
The very impressive Tarbosaurus bataar.  While not the largest of the tyranosaurids certainly had the extremely small arms in comparision  to its body size.  While being ridiculously small, they did support large muscle attachments and were probably used for something.  Hypothesis in regards to their function ranges from holding onto prey and or during mating, to helping it stand up.  The larger skeleton below shows how it could have supported itself on the ground with its arms, or at least stopped the animal from rolling over uncontrollably.  A juvenile Tarbosaurus is mounted in front of its much larger adult form.
The juvenile Tarbosaur was still equipped to be a very successful predator. 

The head of Velociraptor mongoliensis, Dan Telfer has and interesting comedy bit about dinosaurs, likening Velociraptors to scary turkeys.  Though looking at the teeth, claws (on the hands and feet) I would imagine them (they hunted in packs after all) to be more like wolves on two legs, with extra pointy bits to tear at you with.

Avimimus portentosus was very bird-like showing fused tail vertebrae, a toothless or nearly toothless skull (depending on sources),  wrists that folded back towards the forearms, and bumps suggesting attachment points for feathers on the ulna. 
 Looks very much like the bones in a chicken wing.
 

Fossil feathers

Fossil spider

The regular exhibit in the Osaka Museum of Natural History has a number of reconstructions on permanent display.  The stegosaurus was quite impressive.  The Tyrannosaur (not pictured) was decidedly not impressive due to it being mounted in the old school 'Godzilla' posture.  
There was a plaque stating that the museum is aware of this.
 
The Thagomizer at the end of the Stegasaur's tail.  Yes, that's the technical term.

The oldest (living) fossil I photographed that day, fresh foliage on the a Ginkgo in the park.
They turn a brilliant yellow in the fall, though perhaps that's a warning to stay away from the decidedly nasty smelling fruit.

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