Dinosaurs and Fossils

31 Aug 2020

At https://phys.org/news/2020-08-3d-embryonic-sauropod-dinosaur-reveals.html ... a fossil titanosuar embryo with a modified 'egg tooth' or horn (an appendage of some kind that was apparently used to break open the egg during the hatching process). Robert provides a link to https://en.wikipedia.org/wiki/Egg_tooth ... which explains what this feature of anatomy is. Around 25 years ago researchers discovered a massive fossil nesting ground of titanosaurian dinosaurs in Patagonia (southern Argentina). Now we have the discovery at the same site of the first known intact embryonic skull ....

 

These dinosaurs are characterised by small heads on long necks, with long tails. They had a horned face with binocular vision, as embryos, quite different from adult specimens. The research is published in Current Biology. They appear to have hatched out of the egg shell with the help of a horned prominence, rather than a boney 'egg tooth' (see above link to wiki). The image directly above is 3D.

At https://phys.org/news/2020-08-early-cambrian-fossil-discovery-hemichorda... ... an early Cambrian fossil, a proto Hemichordates ...

.. it lived on the sea bottom and fed from the sea bed but at the same time was able to feed in a suspended manner from whatever was floating around in the water above it. It came from the Burgess shale and the researchers also published in Current Biology - see https://doi.org/10.1016/j.cub.2020.07.078 ... the soft parts of the organism were preserved and fossilised in equisite detail. It looks like something you might make from plasticene or play dough.

And then we have sleepy head, at https://phys.org/news/2020-08-fossil-evidence-hibernation-like-state-mil... ... fossil evidence of hibernation in a 250 million year old Antarctic animal (which was unglaciated at the time but the authors seem to assume it was still at the south pole and extremely cold when in effect there is evidence trees were growing). Continental drift would have had the Antarctic somewhere other than the south pole as we are talking way back in the Triassic, prior to the break up of Pangaea. Presumably, in that situation, Antarctica would have been in the extreme south, but it is arguable. I would have to look that up. Might get back on that aspect. The important point for the moment is that this is the oldest evidence yet of hibernation - animals that are able to lower their metabolic rate in order to sleep in a cosy nest underground through the extremes of a cold winter. These animals lived during the Permian - or were part of the mass die off at the end of the Permian (earlier than Triassic). It is assumed they lived into the early Triassic but that may be an artefact of geochronology. Interestingly, they were the size of a pig, had tusks, but no teeth. It is thought they used the tusks to root in the ground like a wild pig. Obviously, they would have foraged amongst a good vegetation landscape or dug out roots and tubers as a pig would. In the modern world badgers are around the same size and hibernate. They also live in a  temperature climate  ... mind you he looks like he lived underground for long periods but that might be down to the artists impression. Not a lot of hair. He is also described as a proto mammal.

Note - at https://en.wikipedia.org/wiki/Fremouw_Formation ... we are told Antarctica was at 70 to75 degrees latitude, well within the south polar circle. However, at www.space.com/2452-giant-crater-tied-worst-mass-extinction.html ... a crater the size of Ohio. The might bounce the earth around.

At https://phys.org/news/2020-08-dinosaur-skeleton-ready-closeup.html ... the first complete dinosaur skeleton ever found. The Scelidosauros. It came from Dorset's Jurassic coast 160 years ago and has lain in a museum behind the scenes storage space for most of that time. It has been taken out and dusted down and written up.