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Reptilian feats: Atlantic-swimming crocodiles and cooperative lizard burrow-digging



From: Ben Creisler
bh480@scn.org


OK--this is not dinosaur stuff but it shows that archosaurs and squamates
should not be underestimated.

Crocodiles swam Atlantic from Africa to Americas
http://www.newscientist.com/article/dn20464-crocodiles-swam-the-atlantic-to-
reach-america.html


Robert W. Meredith, Evon R. Hekkala, George Amato and John Gatesy (2011)
A phylogenetic hypothesis for Crocodylus (Crocodylia) based on
mitochondrial DNA: Evidence for a trans-Atlantic voyage from Africa to the
New World. 
Molecular Phylogenetics and Evolution (advance publication)
doi:10.1016/j.ympev.2011.03.026 

The phylogenetic relationships among extant species of Crocodylus
(Crocodylia) have been inconsistently resolved by previous systematic
studies. Here we used nearly complete mitochondrial (mt) genomes (16,200
base pairs) for all described Crocodylus species, eight of which are new to
this study, to derive a generally well-supported phylogenetic hypothesis
for the genus. Model-based analyses support monophyly of all Asian +
Australian species and paraphyly of Crocodylus niloticus (Nile crocodile)
with a monophyletic New World clade nested within this species. Wild-caught
Nile crocodiles from eastern populations group robustly with the four New
World species to the exclusion of Nile crocodiles from western populations,
a result that is also favored by parsimony analyses and by various
subpartitions of the overall mt dataset. The fossil record of Crocodylus
extends back only to the Late Miocene, while the earliest fossils assigned
to C. niloticus and to New World Crocodylus are Pliocene. Therefore, in
combination with paleontological evidence, mt DNA trees imply a relatively
recent migration of Crocodylus from Africa to the Americas, a voyage that
would have covered hundreds of miles at sea.


McAlpin, S,, Duckett, P,, Stow, A, (2011)
Lizards Cooperatively Tunnel to Construct a Long-Term Home for Family
Members. PLoS ONE 6(5): e19041. doi:10.1371/journal.pone.0019041
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0019041

Constructing a home to protect offspring while they mature is common in
many vertebrate groups, but has not previously been reported in lizards.
Here we provide the first example of a lizard that constructs a long-term
home for family members, and a rare case of lizards behaving cooperatively.
The great desert skink, Liopholis kintorei from Central Australia,
constructs an elaborate multi-tunnelled burrow that can be continuously
occupied for up to 7 years. Multiple generations participate in
construction and maintenance of burrows. Parental assignments based on DNA
analysis show that immature individuals within the same burrow were mostly
full siblings, even when several age cohorts were present. Parents were
always captured at burrows containing their offspring, and females were
only detected breeding with the same male both within- and across seasons.
Consequently, the individual investments made to construct or maintain a
burrow system benefit their own offspring, or siblings, over several
breeding seasons.






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