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Gueragama, new Cretaceous iguanian from Brazil (free pdf) + giant varanids + Machimosaurus



Ben Creisler
bcreisler@gmail.com


A number of recent non-dino papers:


Free pdf:

Tiago R. Simões, Everton Wilner, Michael W. Caldwell,    Luiz C.
Weinschütz & Alexander W. A. Kellner (2015)
A stem acrodontan lizard in the Cretaceous of Brazil revises early
lizard evolution in Gondwana.
Nature Communications 6, Article number: 8149
doi:10.1038/ncomms9149
http://www.nature.com/ncomms/2015/150826/ncomms9149/full/ncomms9149.html



Iguanians are one of the most diverse groups of extant lizards (>1,700
species) with acrodontan iguanians dominating in the Old World, and
non-acrodontans in the New World. A new lizard species presented
herein is the first acrodontan from South America, indicating
acrodontans radiated throughout Gondwana much earlier than previously
thought, and that some of the first South American lizards were more
closely related to their counterparts in Africa and Asia than to the
modern fauna of South America. This suggests both groups of iguanians
achieved a worldwide distribution before the final breakup of Pangaea.
At some point, non-acrodontans replaced acrodontans and became the
only iguanians in the Americas, contrary to what happened on most of
the Old World. This discovery also expands the diversity of Cretaceous
lizards in South America, which with recent findings, suggests
sphenodontians were not the dominant lepidosaurs in that continent as
previously hypothesized.



News and blogs:


http://blogs.egu.eu/network/palaeoblog/2015/08/26/lizard-lizard-on-the-wall/


http://www.forbes.com/sites/shaenamontanari/2015/08/26/ancient-toothy-lizard-is-the-first-of-its-kind-from-south-america/


http://www.palaeocast.com/new-iguana-from-brazil/



==


Humans present when giant varanids still roamed Pleistocene Australia


Gilbert J. Price, Julien Louys, Jonathan Cramb, Yue-xing Feng,
Jian-xin Zhao, Scott A. Hocknull, Gregory E. Webb, Ai Duc Nguyen &
Renaud Joannes-Boyau (2015)
Temporal overlap of humans and giant lizards (Varanidae; Squamata) in
Pleistocene Australia.
Quaternary Science Reviews  125: 98–105
doi:10.1016/j.quascirev.2015.08.013
http://www.sciencedirect.com/science/article/pii/S0277379115300809


Highlights


Australia's giant fossil lizards are thought have been driven extinct by humans.

But previous dates do not show an overlap in time of lizards and humans.

We provide evidence for the geologically youngest fossil record of
giant lizards.

The new record represents a younger range extension by >30 thousand years.

Giant lizards were still extant in Australia at 50 kyr.


Abstract


An obvious but key prerequisite to testing hypotheses concerning the
role of humans in the extinction of late Quaternary ‘megafauna’ is
demonstrating that humans and the extinct taxa overlapped, both
temporally and spatially. In many regions, a paucity of reliably dated
fossil occurrences of megafauna makes it challenging, if not
impossible, to test many of the leading extinction hypotheses. The
giant monitor lizards of Australia are a case in point. Despite
commonly being argued to have suffered extinction at the hands of the
first human colonisers (who arrived by 50 ka), it has never been
reliably demonstrated that giant monitors and humans temporally
overlapped in Australia. Here we present the results of an integrated
U–Th and 14C dating study of a late Pleistocene fossil deposit that
has yielded the youngest dated remains of giant monitor lizards in
Australia. The site, Colosseum Chamber, is a cave deposit in the Mt
Etna region, central eastern Australia. Sixteen new dates were
generated and demonstrate that the bulk of the material in the deposit
accumulated since ca. 50 ka. The new monitor fossil is, minimally, 30
ky younger than the previous youngest reliably dated record for giant
lizards in Australia and for the first time, demonstrates that on a
continental scale, humans and giant lizards overlapped in time. The
new record brings the existing geochronological dataset for Australian
giant monitor lizards to seven dated occurrences. With such sparse
data, we are hesitant to argue that our new date represents the time
of their extinction from the continent. Rather, we suspect that future
fossil collecting will yield new samples both older and younger than
50 ka. Nevertheless, we unequivocally demonstrate that humans and
giant monitor lizards overlapped temporally in Australia, and thus,
humans can only now be considered potential drivers for their
extinction.



====


Apparently this paper from a few months back has not appeared on the
DML (another blocked post it appears). So, better late than never,
I'll try again...



Jeremy E. Martin, Peggy Vincent & Jocelyn Falconnet (2015)
The taxonomic content of Machimosaurus (Crocodylomorpha, Thalattosuchia).
Comptes Rendus Palevol 14(4): 305–310
doi:10.1016/j.crpv.2015.03.006
http://www.sciencedirect.com/science/article/pii/S1631068315000548


Free pdf:

http://www.researchgate.net/publication/278333922_The_taxonomic_content_of_Machimosaurus_(Crocodylomorpha_Thalattosuchia)



Machimosaurus is a large teleosaurid thalattosuchian, a marine
crocodylomorph historically recovered from Upper Jurassic strata of
Europe. Several fragmentary remains are assignable to this genus but
only four complete skulls have been reported, two of which are
currently unavailable for study. A recent revision of the material
assigned to Machimosaurus recognizes four valid species in this genus.
Following a critical review of the diagnostic features of the various
species, we confirm that the genus Machimosaurus is monospecific with
Machimosaurus hugii as the sole and unique representative.