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https://theconversation.com/a-newly-identified-hell-chicken-species-suggests-dinosaurs-werent-sliding-toward-extinction-before-the-fateful-asteroid-hit-221482>
"Were dinosaurs already on their way out when an asteroid hit Earth 66 million
years ago, ending the Cretaceous, the geologic period that started about 145
million years ago? It’s a question that has vexed paleontologists like us for
more than 40 years.
In the late 1970s, debate began about whether dinosaurs were at their peak or
in decline before their big extinction. Scientists at that time noted that
while dinosaur diversity seemed to have increased in the geologic stage that
spanned 83.6 million to 71.2 million years ago, the number of species on the
scene seemed to decrease during the last few million years of the Cretaceous.
Some researchers have interpreted this pattern to mean that the asteroid that
struck the Gulf of Mexico was simply the final blow for an already vulnerable
group of animals.
However, others have argued that what looks like a decrease in the diversity of
dinosaurs may be an artifact of how hard it is to accurately count them. Fossil
formations might preserve different dinosaurs more or less often based on
factors like their favored environment and how easily their bodies fossilized
there. The accessibility of various outcrops could influence what kinds of
fossils researchers have so far found. These biases are a problem because
fossils are what paleontologists must rely on to conclusively answer how
healthy dinosaur populations were when the asteroid hit.
At that crucial moment, what was really happening to dinosaur diversity?
Discovery, identification and description of new dinosaurs provide vital clues.
This is where our work comes in. Close examination of what we’d thought was a
juvenile specimen of an already known species of dinosaur from this time period
revealed that it was actually part of an adult from a completely new species.
Our work focusing on the life stage of our specimen demonstrates that dinosaur
diversity may not have been declining before the asteroid hit, but rather that
there are more species from this time period yet to be discovered – potentially
even through reclassification of fossils already in museum collections."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
