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Turtles turn topical



From: Ben Creisler
bh480@scn.org
Turtles rarely get mentioned on the DML, but a few recent items and papers 
might be of interest in the after-the-holiday lull. (I'm hoping that the 
Yahoo-DML glitch does not garble parts of the text below...)
 
Turtle brains underrated
 
Similar to recent studies of avian intelligence, a number of recent studies 
have countered received wisdom about reptilian intelligence and show that 
modern reptiles are capable of learning, basic reasoning, and problem solving. 
This of course would apply to extinct reptilians as well, who often had 
proportionately larger brains than members of any modern surviving groups.
 
http://www.newscientist.com/article/mg21228440.500-coldblooded-cognition-tortoises-quick-on-the-uptake.html
 
===
Turtle evolution (free pdf)
 
Hiroshi Nagashima, Shigehiro Kuraku, Katsuhisa Uchida, Yoshie Kawashima-Ohya, 
Yuichi Narita and Shigeru Kuratani (2011)
Body plan of turtles: an anatomical, developmental and evolutionary 
perspective. 
Anatomical Science International (advance online publication)
DOI: 10.1007/s12565-011-0121-y
http://www.springerlink.com/content/b5n5x326x4n00554/
Free pdf: http://www.springerlink.com/content/b5n5x326x4n00554/fulltext.pdf
 
 
The evolution of the turtle shell has long been one of the central debates in 
comparative anatomy. The turtle shell consists of dorsal and ventral parts: the 
carapace and plastron, respectively. The basic structure of the carapace 
comprises vertebrae and ribs. The pectoral girdle of turtles sits inside the 
carapace or the rib cage, in striking contrast to the body plan of other 
tetrapods. Due to this topological change in the arrangement of skeletal 
elements, the carapace has been regarded as an example of evolutionary novelty 
that violates the ancestral body plan of tetrapods. Comparing the spatial 
relationships of anatomical structures in the embryos of turtles and other 
amniotes, we have shown that the topology of the musculoskeletal system is 
largely conserved even in turtles. The positional changes see
d to turtle-specific folding of the lateral body wall in the late developmental 
stages. Whereas the
 ribs of other amniotes grow from the axial domain to the lateral body wall, 
turtle ribs remain arrested axially. Marginal growth of the axial domain in 
turtle embryos brings the morphologically short ribs in to cover the scapula 
dorsocaudally. This concentric growth appears to be induced by the margin of 
the carapace, which involves an ancestral gene expression cascade in a new 
location. These comparative developmental data allow us to hypothesize the 
gradual evolution of turtles, which is consistent with the recent finding of a 
transitional fossil animal, Odontochelys, which did not have the carapace but 
already possessed the plastron. 
 
-----
Jérémy Anquetin (2011)
Reassessment of the phylogenetic interrelationships of basal turtles 
(Testudinata)
Journal of Systematic Palaeontology (advance online publication)
DOI:10.1080/14772019.2011.558928
http://www.tandfonline.com/doi/abs/10.1080/14772019.2011.558928
 
Recent discoveries from the Late Triassic and Middle Jurassic have 
significantly improved the fossil record of early turtles. These new forms 
offer a unique opportunity to test the interrelationships of basal turtles. 
Nineteen fossil species are added to the taxon sample of the most comprehensive 
morphological phylogenetic analysis of the turtle clade. Among these additional 
species are recently discovered forms (e.g. Odontochelys semitestacea, 
Eileanchelys waldmani, Condorchelys antiqua), taxa generally omitted from 
previous analyses (e.g. chengyuchelyids, Sichuanchelys chowi) and species 
included in a phylogenetic analysis for the first time (Naomichelys speciosa 
and Siamochelys peninsularis). The coding of several characters is reassessed 
in the light of recent observations, but also in order to reduce unwarranted 
assumptions on character and character state homologies. Additional characters 
from previous analyses, as well as five new ones, are also
 included, resulting in a data matrix of 178 characters scored for 86 turtle 
species and seven fossil outgroups. The dataset resolves the relationships of 
most newly included taxa, with the exception of S. chowi and ‘Chengyuchelys’ 
dashanpuensis. The phylogenetic placement of Heckerochelys romani, Condorchelys 
antiqua and Eileanchelys waldmani as stem turtles more derived than 
Kayentachelys aprix but more basal than Meiolania platyceps and Mongolochelys 
efremovi is corroborated. The relationships of chengyuchelyids remain unclear 
and they are unstable with respect to stem turtles. In contrast to previous 
analyses, Arundelemys dardeni is placed within pleurosternids and Siamochelys 
peninsularis falls within xinjiangchelyids. Perhaps the most salient conclusion 
of the present study is the placement of Naomichelys speciosa as a basal member 
of a clade uniting meiolaniids, Mongolochelys efremovi and Otwayemys 
cunicularius. This clade of rather large stem
 turtles had a worldwide spread during the Mesozoic at least, and persisted 
until the Pleistocene with meiolaniids.
 
===
Gaffney, Eugene S. & Krause, David W. (2011)
Sokatra, a new side-necked turtle (late Cretaceous, Madagascar) and the 
diversification of the main groups of Pelomedusoides.
American Museum novitates, No. 3728
Free pdf: http://digitallibrary.amnh.org/dspace/handle/2246/6147
 
 
Sokatra antitra, n. gen. et sp., is a new side-necked turtle from the 
Maastrichtian (Upper Cretaceous) Maevarano Formation, Mahajanga Basin, 
northwestern Madagascar. Sokatra antitra is based on a series of incomplete 
skulls: a partial skull that lacks the premaxillae and some of the basicranium, 
a partial skull that has a complete ear region and partial basicranium, and 
other isolated specimens, including dentaries. Although this species exhibits 
some features of the North African and Brazilian Euraxemydidae, it does not 
belong to this family, but instead it is the sister taxon of the magnafamily 
Podocnemidera of Gaffney et al. (2006, 2011). Characters of Sokatra uniting it 
with the magnafamily Podocnemidera are: quadratebasisphenoid contact, ventral 
covering of processus interfenestralis of opisthotic, and at least half of 
prootic covered ventrally. The laterally open foramen jugulare posterius and 
the distinct accessory ridge on the maxilla are
 characteristic, but not unique, features shared with members of the 
Euraxemydidae. The presence of a small wall posterior to the columellae auris 
and medial to the incisura columellae auris and the formation of the foramen 
posterius canalis carotici interni by both the prootic and quadrate are unique 
to Sokatra. In a PAUP analysis using the character matrix from Gaffney et al. 
(2006), Sokatra resolves as: (Pelomedusidae, Araripemys (Sokatra (Euraxemydidae 
(Bothremydidae, Podocnemididae)))). The deep phylogenetic roots of Sokatra 
indicates the presence of its lineage on Madagascar prior to the beginning of 
the late Cretaceous.