Amphibious ichthyosaur found

Adam Khor

Lived 248 million years ago:

http://news.nationalgeographic.com/news/2014/11/141105-ichthyosaurs-sea-monsters-dinosaurs-science-fossils/?utm_source=Facebook&utm_medium=Social&utm_content=link_fb20141105news-penguins&utm_campaign=Content&sf5616639=1

Rubecula

well we know they went back to the sea, so it seems reasonable thet they had a halfway stage. Good spot.

Adam Khor

Indeed, it was only a matter of time before they found something like it... still, amazing discovery :cool:

Linnaeus

Hello Adam and all members of the Forum,

I hadn't seen this article on Cartorhynchus lenticarpus before; but it's fascinating and very important for scientific interpretations of evolution.

I would like to know if palaeontologists have been able to trace the origin of Ichthyosaurs back even further, creating a family tree that would recede in time until the earliest completely terrestrial ancestor was identified. I'd also like to know more about the various species of Ichthyosaurs, from the most primitive to the most advanced. What is the earliest true Ichthyosaur known today? If these creatures had not gone into extinction, in what direction do you think thay would have evolved? Might they perhaps have returned definitely to the land, acquiring therapsid characteristics, becoming increasingly mammal-like in appearance and physiological aspects? Would their brain capacity have increased?

Adam Khor

Linnaeus wrote: »

I would like to know if palaeontologists have been able to trace the origin of Ichthyosaurs back even further, creating a family tree that would recede in time until the earliest completely terrestrial ancestor was identified.

Not yet, to my knowledge. We do know of some early sea reptiles such as Hupehsuchus which probably look a lot like the first ichthyosaurs (in fact, Hupehsuchus was proposed as a possible early relative to ichthyosaurs, but there are some important anatomical differences which suggest otherwise.

Linnaeus wrote: »

What is the earliest true Ichthyosaur known today?

Probably Utatsusaurus, Chaohusaurus or Grippia, all from the early Triassic, although they were already fully marine animals so obviously they come from earlier times. Also, some scientists have reclassified them as "ichthyopterygians" outside of Ichthyosauria proper (as always there's no consensus among experts).

Linnaeus wrote: »

If these creatures had not gone into extinction, in what direction do you think thay would have evolved? Might they perhaps have returned definitely to the land, acquiring therapsid characteristics, becoming increasingly mammal-like in appearance and physiological aspects? Would their brain capacity have increased?

I see no reason why they would have returned to land; if anything they seemed to become more and more adapted to the sea as time went by (even the early and mid Triassic forms seem fully marine and probably gave birth in the sea already). I'm not even sure they would've changed much, as they were so beautifully adapted to what they did, but one can imagine say, giant filter feeding forms, things like that... As for brain capacity, they did very well for millions of years with what they had, so I doubt they would have evolved into cetacean-like types, mind-wise (keep in mind they were visual rather than auditive creatures, and apparently rather deaf, so they wouldn´t develop a communication system like that of dolphins, = they would probably not develop such a complex society either = no need for dolphin-like intelligence. In many ways they were more like crocodiles or sharks).