New refs

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
Here are a few new refs that may not have been mentioned 
yet:
Sanz, L.S. & F. Ortega. 2002. The birds from Las Hoyas. 
Science Progress 85(2):113-130
Information on the first steps of the avian evolutionary 
history has dramatically increased during the last few 
years. The fossil record provides a general view of the 
morphological changes of the avian flight apparatus from 
nonvolant ancestors (non-avian theropod dinosaurs) to the 
first derived fliers of the Early Cretaceous. The Las 
Hoyas bird record includes three genera: Iberomesornis, 
Concornis and Eoalulavis. This fossil material has yielded 
information about the early avian evolutionary history. 
These Early Cretaceous birds (some 120 million years old) 
had a wingbeat cycle and breathing devices similar to 
those of extant birds. The function of the rectricial facn 
was also similar. In the evolutionary transition from 
cursorial ancestors to derived fliers it is possible to 
verify a trend to increase lift. Primitive wing aspect 
ratio morphotypes were elliptical ones, other derived 
morphotypes appeared, for example, in the Neornithes 
(extant birds). Some primitive fliers, like the Las Hoyas 
genus Eoalulavis, had alula (feather attached to the first 
digit of the hand) similar to that of present day birds, 
indicating braking and manoeuvering skills similar to 
those of their extant relatives. Primitive avian life 
habits are poorly understood. Some evidence from the Las 
Hoyas bird record indicates that Early Cretaceous birds 
present in the trophic chains.

Hedenström, Anders  2002. Aerodynamics, evolution and 
ecology of avian flight . Trends in Ecology & Evolution. 17
(9): 415-422. 
Animal flight poses intriguing questions about biological 
adaptation, from how flight could have evolved to the 
morphological and physiological designs that enable flight 
to occur. Aerodynamic theory provides ecologists with a 
useful tool for understanding the basic physics of flight, 
but analysing flapping flight aerodynamics in birds is 
difficult, with interesting physiological complications. 
Recent research, using sophisticated techniques, has 
generated new and exciting insights about the evolution of 
flight, the function of tails and the ecological 
adaptations to a flying lifestyle. 
Key Passages:
Archaeopteryx: analysing the flight of a fossil
The arboreal scenario can easily explain how take off was 
accomplished and how an incipient wing would have 
gradually improved flight performance, although the 
feathered dinosaurs favour the cursorial hypothesis. For 
take off from the ground, proavis would have needed to 
reach a sufficiently high forward speed on the runway 
[which is given by the minimum power speed of the power 
curve (Box 1)]. This problem was analysed recently for 
Archaeopteryx, the oldest known bird, living 150 million 
years ago [24]. The literature about this fossil is huge, 
and controversy still rages regarding the species flight 
capability [15]. The main problem is that the estimated 
top running speed of Archaeopteryx is 2 ms-1, whereas the 
speed required for take off is at least 6 ms-1, thus 
making it impossible for Archaeopteryx to have been able 
to take off from the ground [18]. 
Using estimated morphology for Archaeopteryx, Burgers and 
Chiappe [25] modelled the force dynamics from standstill 
through a take-off run ( Fig. 2). At speed V = 0, the 
weight is balanced by an equal and opposite force on the 
feet. When starting to run, the hind limbs produce forward 
propulsion and, by flapping the wings simultaneously, the 
feet generate a forward thrust that increases the 
acceleration. The wings also generate lift force, but, 
during running, this is residual lift, because it does not 
act on the bird, but relieves the hindlimbs from `weight 
support' and so the vertical force on the feet is reduced. 
This is the `vertical force migration' from the hind limbs 
to the wings, and the reduced weight support causes a 
further acceleration by this feedback, which in turn 
increases the residual lift on the wings and hence the 
acceleration. Similarly, there is a `horizontal force 
migration' from hind limb propulsion to increasing wing 
thrust during the taxiing run (Fig. 2). Taken together, 
the flapping wings increase acceleration and the top 
running speed from a mere 2 ms-1 to 7.8 ms-1 when lift 
equals weight, and thus Archaeopteryx would have taken off 
from the ground, with the help of flapping wings. Even 
though it is based on assumed morphology and weight, this 
aerodynamic model shows that Archaeopteryx could have used 
powered flight and was probably quite an advanced flyer. 
One can also envisage that feathered and winged dinosaurs 
[21] could have likewise increased their running speed by 
using wing thrust, and that bird flight therefore evolved 
from the ground up. 

HECKERT, ANDREW B. and SPENCER G. LUCAS, 2002. SOUTH 
AMERICAN OCCURRENCES OF THE ADAMANIAN (LATE 
TRIASSIC:LATEST CARNIAN) INDEX TAXON STAGONOLEPIS 
(ARCHOSAURIA: AETOSAURIA) AND THEIR BIOCHRONOLOGICAL 
SIGNIFICANCE. Journal of Paleontology 76(5): 852?863.
Aetosaur fossils from the Upper Triassic Ischigualasto 
Formation of Argentina formerly assigned to Aetosauroides 
scagliai Casamiquela and Argentinosuchus bonapartei  
Casamiquela are reassigned to Stagonolepis robertsoni 
Agassiz (small specimens) and  S. wellesi > (Long and 
Ballew) (larger specimens). Numerous features of the 
skull, vertebral column, appendicular skeleton, and 
particularly the armor, of these Argentinian aetosaurs are 
identical to those of Stagonolepis > and differ from other 
aetosaurs. Identification of Stagonolepis > in South 
America has important implications for the correlation of 
nonmarine strata across Late Triassic Pangea. Stagonolepis 
<> is an index taxon of the Adamanian land-vertebrate 
faunachron of latest Carnian age. Its occurrences in the 
Ischigualasto and Santa Maria formations, as well as at 
the type locality in the Lossiemouth Sandstone of Scotland 
and in the Blasensandstein of the German Keuper, cross-
correlate with a well-established tetrapod biostratigraphy 
of the Chinle Group in western North America. Thus, all 
Stagonolepis  records are of Adamanian (latest Carnian) 
age, not Otischalkian (early or ?middle? Carnian) age, as 
proposed by some earlier workers. This correlation also 
demonstrates that the oldest known dinosaurs are not from 
the Ischigualasto and Santa Maria formations. Previous 
workers obtained radioisotopic dates of 227.8 Ma from the 
Ischigualasto Formation, providing a maximum numerical 
date for Stagonolepis -bearing units. This date must be 
late Carnian, not of Ladinian age, and thus supports the 
apparent age of the Ladinian-Carnian boundary (232 Ma) of 
time scales based on the Newark Supergroup in eastern 
North America.

DYKE, GARETH J. 2002. SHOULD PALEONTOLOGISTS 
USE ?PHYLOGENETIC? NOMENCLATURE?. Journal of Paleontology 
76(5): 793?796.

New Issue of  Palaeontologica Electronica 5(1) with 
reviews of recent dinosaur books