Dinos and Mesozoic birds--some new papers but no new taxa

[bh480@scn.org]

Polar Dinosaurs
Thomas H. Rich, Patricia Vickers-Rich, Roland A. Gangloff.
Polar Dinosaurs. Science (295): 979-980 (Feb. 8, 2002) 
During the past 20 years, much evidence for dinosaurs that 
lived in polar regions has been unearthed. These dinosaurs 
may have been particularly adapted to extreme conditions, 
but establishing exactly what these conditions were is 
fraught with difficulties. In their Perspective, Rich et 
al. chart what is known about polar dinosaurs and their 
habitat, particularly in southeastern Australia and 
Alaska. 

Mohabey, D.M. 2001. Indian dinosaur eggs: A review. 
JOURNAL OF THE GEOLOGICAL SOCIETY OF INDIA. 58 (6): 479-
508 (DEC 2001) 
Review of the available work on Indian dinosaurs shows 
that the majority of Indian dinosaur fossils are better 
known from Late Cretaceous sediments (Lameta and 
equivalents) than from the older pre-Late Cretaceous 
sediments or Gondwana Group (Triassic to Late Jurassic). 
Dinosaur eggs are so far unknown in the pre-Lameta 
dinosaur-bearing sediments represented by Maleri 
(Carnian), Dharamaram (Norian to Rhaetian) and Kota 
(Liassic) Formations. Of these, the Kota Formation has 
yielded near-complete skeletons of Barapasaurus tagorei (a 
primitive sauropod) and Kotasaurus yamanapalliensis (a 
transitional prosauropod to early sauropod), which are at 
present the only two mounted dinosaur skeletons in 
India.The present article provides a brief historical 
review of the work on Indian dinosaurs. The stratigraphy, 
geology and geographical distribution of dinosaur-bearing 
sediments are discussed. The systematics of the Indian 
dinosaur species are briefly described. As the present 
author is mostly involved with the study of Indian 
Cretaceous dinosaurs and their eggs, it would only be apt 
in this article to place emphasis on Late Cretaceous 
dinosaurs and their eggs. A wide diversity is observable 
in the Indian dinosaur eggs, which are parataxonomically 
assigned to oofamily Megaoolithidae, Elongatoolithidae and 
Spheroolithidae. The problems involved in relating the 
varied Indian egg oospecies to their parent dinosaur are 
very challenging. However, based on the existing 
knowledge, the megaloolithid and elongatoolithid eggs can 
be attributed to titanosaurid and abelisaurid dinosaurs. 
Nesting behaviour of these dinosaurs is discussed in this 
paper. Evidences suggest that the environment during Late 
Cretaceous in India provided an ideal niche for the 
preferred habitat of these dinosaurs having an acme of 
their breeding and nesting. However, these reptiles 
struggled to survive the initial onslaught caused by the 
Deccan volcanic eruption near the end of Cretaceous.

G. P. Ericson; Les Christidis; Alan Cooper; Martin 
Irestedt; Jennifer Jackson; Ulf S. Johansson; Janette A. 
Norman Source. 2002. A Gondwanan origin of passerine birds 
supported by DNA sequences of the endemic New Zealand 
wrens. Proceedings of the Royal Society of London: 
Biological Sciences (269: 1488): 235 -- 241.
 Zoogeographic, palaeontological and biochemical 
data support a Southern Hemisphere origin for passerine 
birds, while accumulating molecular data suggest that most 
extant avian orders originated in the mid-Late Cretaceous. 
We obtained DNA sequence data from the nuclear c-myc and 
RAG-1 genes of the major passerine groups and here we 
demonstrate that the endemic New Zealand wrens 
(Acanthisittidae) are the sister taxon to all other extant 
passerines, supporting a Gondwanan origin and early 
radiation of passerines. We propose that (i) the 
acanthisittids were isolated when New Zealand separated 
from Gondwana (ca. 82-85 Myr ago), (ii) suboscines, in 
turn, were derived from an ancestral lineage that 
inhabited western Gondwana, and (iii) the ancestors of the 
oscines (songbirds) were subsequently isolated by the 
separation of Australia from Antarctica. The later spread 
of passerines into the Northern Hemisphere reflects the 
northward migration of these former Gondwanan elements. 

Schweitzer, M.H. & Marshall, C.L. 2001. A molecular model 
for the evolution of endothermy in the Theropod-Bird 
lineage. JOURNAL OF EXPERIMENTAL ZOOLOGY. DEC 15 2001; 291 
(4) : 317-338
Ectothermy is a primitive state; therefore, a shared 
common ancestor of crocodiles, dinosaurs, and birds was at 
some point ectothermic. Birds, the extant descendants of 
the dinosaurs, are endothermic. Neither the metabolic 
transition within this lineage nor the place the dinosaurs 
held along the ectothermic-endothermic continuum is 
defined. This paper presents a conceptual model for the 
evolution of endothermy in the theropod-bird lineage. It 
is recognized that other animals (some fish, insects, 
etc.) are functionally endothermic. However, endothermy in 
other clades is beyond the scope of this paper, and we 
address the onset of endothermy in only the theropod/bird 
clade. The model begins with simple changes in a single 
gene of a common ancestor, and it includes a series of 
concomitant physiological and morphological changes, 
beginning perhaps as early as the first archosaurian 
common ancestor of dinosaurs and crocodiles. These changes 
continued to accumulate within the theropod-avian lineage, 
were maintained and refined through selective forces, and 
culminated in extant birds. Metabolic convergence or 
homoplasy is evident in the inherent differences between 
the endothermy of mammals and the endothermy of extant 
birds. The strength and usefulness of this model lie in 
the phylogenetic, genetic, evolutionary, and adaptive 
plausibility of each of the suggested developmental steps 
toward endothermy. The model, although conceptual in 
nature, relies on an extensive knowledge base developed by 
numerous workers in each of these areas. In addition, the 
model integrates known genetic, metabolic, and 
developmental aspects of extant taxa that phylogenetically 
bracket theropod dinosaurs for comparison with information 
derived from the fossil record of related extinct taxa. 


Dyke, G.J. 2001. The evolutionary radiation of modern 
birds: Systematics and patterns of diversification. 
Geological Journal. 2001; 36(3-4): 305-315
The timing of the evolutionary radiation of the 
modern, or neornithine, birds is controversial. The fossil 
record has indicated that the radiation occurred mainly in 
the aftermath of the Cretaceous-Tertiary (KT) extinction 
event. However, recent estimates of lineage divergengce 
times calculated from molecular data have instead 
indicated that most of the major clades of modern birds 
originated in the Cretaceous. Because the known Mesozoic 
fossil record of modern birds is poor, fossils from the 
early Tertiary provide the first opportunity to document 
the pattern of the radiation. The limited phylogenetic 
hypotheses produced to date and including this post-KT 
fossil material suggest that only some of the 'more basal' 
clades of modern birds were, most likely, present during 
the Mesozoic Era, and that the radiation of the 'more 
derived' landbird group of clades occurred in the early 
Tertiary.