Recent articles (non-dinosaur)

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
With the December 2001 issue of Canadian Earth Sciences 
now out to provide lots of dino stuff, I thought I would 
pass on some recent non-dino articles I don't believe have 
been mentioned here yet. I included a couple of synapsid 
refs, since I recall somebody asking about non-mammalian 
synapsid news in the past month or so.

Muldera, E. 2001. Co-ossified vertebrae of mosasaurs and 
cetaceans: implications for the mode of locomotion of 
extinct marine reptiles. Paleobiology: Vol. 27, No. 4, pp. 
724-734.
 Co-ossified pygal and caudal vertebrae in Late Cretaceous 
mosasaurs from the southeast Netherlands, northeast 
Belgium, and North America are compared with lumbar and 
caudal vertebrae from fossil and extant whales. Both 
infectious spondylitis and idiopathic vertebral 
hyperostosis afflicted these marine tetrapods. The causes 
of the infectious disease and of the idiopathic disease 
are similar in the compared life forms. The location of 
idiopathic hyperostosis along the vertebral column 
implicates axial locomotion in mosasaurs, as in whales.


O'Keefe, F. 2001. Ecomorphology of plesiosaur flipper 
geometry. JOURNAL-OF-EVOLUTIONARY-BIOLOGY. NOV 2001; 14 
(6) : 987-991
The Plesiosauria is an extinct group of marine 
reptiles once common in mesozoic seas. Previous work on 
plesiosaur hunting styles has suggested that short-necked, 
large-headed animals were pursuit predators, whereas long-
necked, small-headed animals were ambush predators. This 
study presents new data on the aspect ratios (ARs) of 
plesiosaur flippers, and interprets these data via 
comparison with AR in birds, bats and aircraft. 
Performance trade-offs implicit in AR variation are well-
understood in the context of aircraft design, and these 
trade-offs have direct ecomorphological analogues in birds 
and bats. Knowledge of these trade-offs allows 
interpretation of variation in plesiosaur AR. By analogy, 
short-necked taxa were specialized for manoeuvrability and 
pursuit, whereas long-necked taxa were generally 
specialized for efficiency and cruising. These 
interpretations agree with previous assessments of maximum 
swimming speed.

Rubidge,  B. S. & Sidor, C. A., 2001. Evolutionary 
patterns among Permo-Triassic therapsids. ANNUAL-REVIEW-OF-
ECOLOGY-AND-SYSTEMATICS. 2001; 32 : 449-480
A rich fossil record documents nonmammalian evolution. 
In recent years, the application of cladistic methodology 
has shed valuable light on the relationships within the 
therapsid clades Biarmosuchia, Dinocephalia, Anomodontia, 
and Cynodontia. Recent discoveries from South Africa 
suggest that Gondwana, rather than Laurasia, was the 
center of origin and radiation for many early therapsids. 
Because of their relative abundance and global 
distribution, therapsids have enjoyed widespread use in 
biostratigraphy, basin analysis, and paleo-environmental 
and -continental reconstructions. Synapsids (including 
therapsids) form the bulk of tetrapod diversity (in terms 
of both number of species and abundance) from Early 
Permian to Middle Triassic times and thus can provide 
critical information on the nature of the Permo-Triassic 
extinction in the terrestrial realm. Quantitative 
techniques have produced headway into understanding the 
relative importance of homoplasy and convergent evolution 
in the origin of mammals.

Modesto, S., Sidor, C.A., Rubidge, B.S. & Welman, J. 2001. 
A second varanopseid skull from the Upper Permian of South 
Africa: implications for Late Permian 'pelycosaur' 
evolution. LETHAIA. DEC 2001; 34 (4) : 249-259
Late Permian terrestrial faunas of South Africa and 
Russia are dominated taxonomically and ecologically by 
therapsid synapsids. On the basis of a single specimen 
from the Upper Permian of South Africa, the varanopseid 
Elliotsmithia longiceps is the sole basal synapsid 
('pelycosaur') known from Gondwana. Recent fieldwork in 
the Upper Permian of South Africa has produced a second 
varanopseid specimen that is referrable to Elliotsmithia. 
Data from both this specimen and the holotype suggest that 
Elliotsmithia forms a clade with Mycterosaurus from the 
Lower Permian of North America and Mesenosaurus from the 
Upper Permian of Eastern Europe. That postulate is 
supported by the three most parsimonious trees discovered 
in a new analysis of varanopseid phylogeny. However, the 
available data cannot resolve the interrelationships of 
these three genera. The new phylogenetic results contrast 
with earlier work identifying Elliotsmithia as the basal 
member of a clade that includes the North American taxa 
Aerosaurus, Varanops, and Varanodon. The new trees reduce 
the stratigraphic debt required by the latter scenario, 
and the one with the least stratigraphic debt identifies 
Elliotsmithia and Mesenosaurus as sister taxa. Two new 
taxa are erected, Mycterosaurinae and Varanodontinae, for 
the two varanopseid subclades.