Soft tissue shows ichthyosaur was warm-blooded, had blubber and camouflage

Science

(Dr. Patrick Trischitta) #1

(John Harshman) #2

If this is true, it’s extremely cool.

Here’s the real paper in Nature, which is of course paywalled.


(Robert Byers) #3

who says its a reptile? If warm blooded its just a good idea for that creature. it should not define the creature or place it in divisions in nature.
I think YEC would welcome it being warm blooded. i do.


(Ashwin S) #4

Seems to be another remarkable example of convergence…


(Ashwin S) #5

One intriguing comment in the abstract is as below -

Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.

wonder if they are talking about constraints at the molecular level leading to the same solutions.


(T J Runyon) #6

What…? I want to be sure here. Are you asking how we know Ichthyosaurs are reptiles?


(Ashwin S) #7

Its a fair question (even though the answer may be obvious to scientists).
It deviates from reptiles in many ways…
Its warm blooded… its viviparous… etc…
what exactly makes a reptile a reptile?


(John Harshman) #8

Phylogeny. And phylogeny is diagnosed by preserved characters. Ichthyosaurs are somewhat problematic because they’ve been so heavily modified, but primitive ones are somewhat easier. They have a number of bones in the skull that have been lost or transformed in warm-blooded synapsids, most notably. They have the upper temporal fenestra. It gets more technical from there.

There are of course other warmblooded reptiles: some sea turtles and all birds. There are other viviparous reptiles: a number of snakes and, perhaps, mosasaurs.


(Ashwin S) #9

So “warm bloodedness”, viviparity etc in this case are not considered preserved ?.. are they pegged as convergent features?
I have always wondered how you guys figure out which features are easy to loose and gain and loose and gain again…


(Joel Duff) #10

Hmm, why did they need blubber when they lived in the warm pre-Flood oceans? YECs often speak of blubber as a emergent trait resulting from adaptation to the Ice Age after the Flood. There theories certainly have difficulty anticipating new results like this.


(John Harshman) #11

I doubt you have actually wondered, because if you really had you could have looked into the literature to find out. The way you find out if characters are homologous or homoplasious is to map them onto phylogenetic trees. Ichthyosaurs are diapsids, and the primitive condition in diapsids is oviparity and “cold-bloodedness”. Mammals are synapsids, with the same primitive conditions. Ergo convergence.


(Blogging Graduate Student) #12

What “molecular constraints” do you have in mind?


(The Honest Skeptic) #13

@evograd


(Blogging Graduate Student) #14

One of my favourite parts of being in a highly active research department is being privy to the stream of “behind the scenes” information. Upcoming papers and projects, new directions of research, that sort of thing. I know a few of the authors of this paper, so I got to hear about this research over a month ago. Very cool indeed. Who knows, I might even get to contribute to some future work along the same lines.


(Joshua Hedlund) #15

I encourage you to be a little more charitable to Ashwin_s. Speaking only for myself, there are many things I wonder about evolutionary theory as a layman that I simply do not have the scientific background to properly investigate and understand directly from the literature. I tend to read popular science books and browse forums like these to increase my overall understanding, often finding questions answered but also often not finding the right details provided to answer the question from the perspective I am coming from.

In this case - how do we know the trees are right? Haven’t there been instances of species that were assumed to be related by ancestry due to shared traits that were later determined by DNA sampling to be non-related and convergent?

A general rule, which I have never seen explicitly stated but that I have picked up through reading (and am happy to be corrected), is that it seems that bones are generally more likely to be more “preserved” (i.e. all mammals having the same organization of limb bones, just with different shapes), with external stuff generally being more likely to be convergent. This is intuitive for obvious developmental reasons, though of course there are many degrees and exceptions and levels of confidence that depend on the amount of evidence available.


(John Harshman) #16

Well, of course we don’t. Nothing in science is known with absolute certainty. But a great deal is known well enough for practical purposes.

Yes, and there have also been instances of supposed convergence that have later turned out to be homologous. Molecular data have been a very big help in phylogenetics.

I can’t say that’s a general rule, but i depends on what you mean by “external stuff”. Color and size are certainly quite labile. Ichthyosaurs, interestingly, have some odd and quite rare changes in bones; for example, they tend toward extreme polydactyly, having extra digits with extra phalanges embedded in their flippers.


(Dan Eastwood) #19

A post was merged into an existing topic: Byers’ Notion of Kinds


(John Mercer) #20

This creature is warm-blooded. Do think that it is not a fish?
https://goo.gl/images/jRDdGm

I mean the creatures in the foreground.:grinning: