Tetrapod Zoology

Terrestrial elapids, take 2

i-da4aae4cc20e4e797ccbff2a974b6736-sea_snakes_elapid_phylogeny.jpg

You might not believe me if I told you how much stuff I have going on right now. In, as ever, an effort to put at least something new on the blog, here’s a pretty picture taken from a talk I give (or gave) on marine reptiles. Alas, I have yet to finish the Tet Zoo series on sea snakes: part I was here, part II here, I suppose I might republish them here at ver 2 some time. Aipysurus-group hydrophiids also made a brief appearance here. Finally, the ‘Rasmussen 2002′ alluded to in the picture is…

Rasmussen, A. R. 2002. Phylogenetic analysis of the “true” aquatic elapid snakes Hydrophiinae (sensu Smith et al., 1977) indicates two independent radiations into water. Steenstrupia 27, 47-63.

Back to work…

Comments

  1. #1 Neil
    October 14, 2008

    So tiger snakes are descended from sea snakes!? After the recent work on birds jumbling everything around, much more than this and Ill have to forget everything I learned and start again lol

  2. #2 Adam
    October 14, 2008

    If this tree is right and the theory that snakes in general are descended from marine lizards is correct, then it means snake ancestors have been in and out of the ocean quite a lot. Originally marine tetrapods which moved onto land, became secondarily marine, lost limbs, moved back on land, moved back into water, and then back onto the land again. Crazy!

  3. #3 Jared
    October 14, 2008

    I still think you should have some fun with the highly polyphyletic dumping ground that is Colubridae.

  4. #4 John Scanlon FCD
    October 15, 2008

    It was a nice idea (it was Garth Underwood’s idea first – in 1957 – as far as I know), but Rasmussen 2002 did not include enough terrestrial taxa and also omitted characters that would have supported monophyly of terrestrial and marine clades. I’m still not happy with the molecular or combined-data resolution for the Australasian elapids (too many taxa keep jumping up and down the stem), but without a radically new set of characters of very low homoplasy, morphology-alone is just not going to find a nearly-unique topology. Pains me to admit it after thirty years of trying.
    But we need more morphological characters anyway, to place the fossils to calibrate the molecular rates in the total-evidence tree…

  5. #5 Darren Naish
    October 15, 2008

    Yay – John arrives at last. You know, this article was deliberately put there as bait just to reel you in :)

    Seriously… agree with you totally, but, so far as I recall, Rasmussen (2002) put enough caveats in there to show that the ‘secondarily terrestrial’ idea was, well, an idea, and not one that was supported by all the data.

    Jared: yes, ‘colubrids’ are on the to-do list. I’ve made a start on xenodontines.

  6. #6 Dean
    October 16, 2008

    I don’t really buy that phylogeny. Laticauda may be sister to the Australo-Papuan radiation; this could be evidence for this idea, but it is rather weak evidence. Based on current molecular data, the other marine taxa are recovered in a clade nested within terrestrial forms.

  7. #7 M.A.Woodley
    October 19, 2008

    Interesting, this looks like yet another exception to Dollo’s “law”. I am reminded also of the phasmids which managed to regain the power of flight a number of times during their evolution.

    See: Whiting, M.F., Bradler, S. and Maxwell, T., Loss and recovery of wings in stick insects, Nature 421: 264267, 2003.

  8. #8 David Marjanovi?
    October 20, 2008

    Tertiarily terrestrial snakes would be so cool… almost as cool as tertiarily wingless stick insects…

    without a radically new set of characters of very low homoplasy, morphology-alone is just not going to find a nearly-unique topology.

    Having enough fossils in the matrix would probably help a lot. Exhibits A, B and C: Whippomorpha, Daedalornithes, (Macroscelidea + Paenungulata).