1 year, 11 months ago
What do turtles and crocodiles share in common? Were crocodiles once a specie of turtle?
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M$1 Answer
Turtles and crocodiles are both cold-blooded reptiles.
Crocodiles were never a species of turtle. They came much earlier. The earliest crocodile appeared around 320 million years ago, whereas the earliest form of turtle, which had only the belly-plate, appeared 220 million years ago.
Crocodiles were the dominant form of large land-based vertebrate until dinosaurs appeared around 235 million years ago, which means that crocodilians ruled the land from 320-235 million years, i.e. for around 85 million years, and they came in many forms, large and small... some were as small as modern lizards, others had long legs and slender bodies like dogs (called the crocodog) and some were bipedal and virtually indistinguishable from a Plateosaurus from the outside.
For five million years, from 235 million to 230 million BC, dinosaurs and crocodilians competed for domination, until finally the dinosaurs won out (evidently because early dinosaurs had a primative form of body-temperature control which we see today as the warm-bloodedness of birds).
It was about 10 million years after dinosaurs forced the crocodilians into submission that turtles with shells first started to appear...
Evidently life among-and-between dinosaurs always motivated the evolution of body-armor in the slower species.
Crocodiles were never a species of turtle. They came much earlier. The earliest crocodile appeared around 320 million years ago, whereas the earliest form of turtle, which had only the belly-plate, appeared 220 million years ago.
Crocodiles were the dominant form of large land-based vertebrate until dinosaurs appeared around 235 million years ago, which means that crocodilians ruled the land from 320-235 million years, i.e. for around 85 million years, and they came in many forms, large and small... some were as small as modern lizards, others had long legs and slender bodies like dogs (called the crocodog) and some were bipedal and virtually indistinguishable from a Plateosaurus from the outside.
For five million years, from 235 million to 230 million BC, dinosaurs and crocodilians competed for domination, until finally the dinosaurs won out (evidently because early dinosaurs had a primative form of body-temperature control which we see today as the warm-bloodedness of birds).
It was about 10 million years after dinosaurs forced the crocodilians into submission that turtles with shells first started to appear...
Evidently life among-and-between dinosaurs always motivated the evolution of body-armor in the slower species.
You can leave an optional "tip" with Mahalo's virtual currency, Mahalo Dollars. If you are asking a difficult question that might require some research, or if you'd like a wide variety of feedback, a higher tip often leads to more answers to your question.
M$
Crocodiles and turtles both appeared around 220 million years ago. They are not particularly closely related, however as they came from different branches of the reptile tree. Turtles are descendants of the older Anapsida branch while Crocodiles descended from the Diapsida branch. This is the accepted classic view, although some recent genetic research indicates that the turtles may be Diapsida too; but, that is uncertain and still neither would be a descendant of the other.
http://news.nationalgeographic.com/news/2004/08/0825_040825_crocodiles_fossils.html
http://news.nationalgeographic.com/news/2008/11/081126-oldest-turtle.html
http://content.usatoday.com/communities/sciencefair/post/2010/03/dinosaur-ancestors-split-from-crocodiles-early/1
http://en.wikipedia.org/wiki/Reptile
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC24355/
I watched a discovery documentary on blue water deep cave diving where they found a crocodile fossil and the man theorized that crocodiles could have originated from turtles. Why do you think he made that statement?