[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

New Cretaceous bird and other papers



From: Ben Creisler bh480@scn.org
New Cretaceous bird and other papers

Here are the citations and abstracts for some new papers 
(one not so new but maybe of interest).

Varricchio, David J. 2002.  A new bird from the Upper 
Cretaceous Two Medicine Formation of Montana.
Canadian Journal of Earth Sciences 39(1): 19-26 
Abstract: A partial humerus, ulna, and radius compose the 
type specimen of a new bird, Piksi barbarulna, new genus 
and species, from the Late Cretaceous (Campanian) Two 
Medicine Formation of western Montana. This 
ornithothoracine taxon differs from all other birds in 
having an enlarged dorsal epicondyle and a reduced ventral 
condyle on the humerus with corresponding modifications on 
the articular surface of the ulna. Among modern birds, 
Piksi is most similar to galliforms, but the paucity of 
unambiguous characters and its unusual morphology defy 
placement within any extant "order" and strongly questions 
any neornithine affinities. Instead, Piksi appears to have 
a fairly basal position within Ornithothoraces. Several 
morphologic features of Piksi occur in phylogenetically 
diverse but morphologically similar birds, such as 
galliforms, tinamous, and some columbiforms. The new bird 
comes from an inland, relatively dry paleo-environment. 
Atypical for a Cretaceous avian record dominated by 
waterfowl, Piksi appears to represents a heavy-bodied 
ground bird. Searching of inland depositional environments 
may yield new and ecologically distinct avian varieties. 

 Haring-E , Kruckenhauser-L , Gamauf-A , Riesing-MJ & 
Pinsker-W. 2001. The complete sequence of the 
mitochondrial genome of Buteo buteo (Aves, Accipitridae) 
indicates an early split in the phylogeny of raptors
MOLECULAR-BIOLOGY-AND-EVOLUTION. OCT 2001; 18 (10) : 1892-
1904
AB: The complete sequence of the mitochondrial (int) 
genome of Buteo buteo was determined. Its gene content and 
nucleotide composition are typical for avian genomes. Due 
to expanded noncoding sequences, Buteo possesses the 
longest mt genome sequenced so far (18,674 bp). The gene 
order comprising the control region and neighboring genes 
is identical to that of Falco peregrinus, suggesting that 
the corresponding rearrangement occurred before the 
falconid/accipitrid split. Phylogenetic analyses performed 
with the nit sequence of Buteo and nine other nit genomes 
suggest that for investigations at higher taxonomic levels 
(e.g., avian orders), concatenated rRNA and tRNA gene 
sequences are more informative than protein gene sequences 
with respect to resolution and bootstrap support. 
Phylogenetic analyses indicate an early split between 
Accipitridae and Falconidae, which, according to molecular 
dating of other avian divergence times, can be assumed to 
have taken place in the late Cretaceous 65-83 MYA.

Christiansen-P. 2002. Mass allometry of the appendicular 
skeleton in terrestrial mammals.
JOURNAL  OF MORPHOLOGY. FEB 2002; 251 (2) : 195-209.
AB: Most analyses on allometry of long bones in 
terrestrial mammals have focused on dimensional allometry, 
relating external bone measurements either to each other 
or to body mass. In this article, an analysis of long bone 
mass to body mass in 64 different species of mammals, 
spanning three orders of magnitude in body mass, is 
presented. As previously reported from analyses on total 
skeletal mass to body mass in terrestrial vertebrates, the 
masses of most appendicular bones scale with significant 
positive allometry. These include the pectoral and pelvic 
girdles, humerus, radius+ulna, and forelimb. Total 
hindlimb mass and the masses of individual hindlimb bones 
(femur, tibia, and metatarsus) scale isometrically. 
Metapodial mass correlates more poorly with body mass than 
the girdles or any of the long bones. Metapodial mass 
probably reflects locomotor behavior to a greater extent 
than do the long bones. Long bone mass in small mammals 
(<50 kg) scales with significantly greater positive 
allometry than bone mass in large (>50 kg) mammals, 
probably because of the proportionally shorter long bones 
of large mammals as a means of preserving resistance to 
bending forces at large body sizes. The positive 
allometric scaling of the skeleton in terrestrial animals 
has implications for the maximal size attainable, and it 
is possible that the largest sauropod dinosaurs approached 
this limit.