Author Archives: LS

News flash: Bird fingers 

"Embryological Evidence Identifies Wing Digits in Birds as Digits 1, 2, 
and 3"

Koji Tamura, Naoki Nomura, Ryohei Seki, Sayuri Yonei-Tamura, and Hitoshi
Yokoyama

Science 11 February 2011:
Vol. 331 no. 6018 pp. 753-757
DOI: 10.1126/science.1198229

Abstract:

The identities of the digits of the avian forelimb are disputed. Whereas
paleontological findings support the position that the digits correspond 
to digits one, two, and three, embryological evidence points to digit 
two, three, and four identities. By using transplantation and 
cell-labeling experiments, we found that the posteriormost digit in the 
wing does not correspond to digit four in the hindlimb; its progenitor 
segregates early from the zone of polarizing activity, placing it in the
domain of digit three specification. We suggest that an avian-specific 
shift uncouples the digit anlagen from the molecular mechanisms that 
pattern them, resulting in the imposition of digit one, two, and three 
identities on the second, third, and fourth anlagens.

Cheers!!

--Mikko

This foot was made for walking 

The discovery that Australopithecus had arched feet suggests this human
ancestor had already abandoned life in the trees

http://www.guardian.co.uk/science/2011/feb/10/fossil-foot-bone-ancestors-walking

The transition to full-time terrestrial bipedality is a hallmark of human
evolution. A key correlate of human bipedalism is the development of
longitudinal and transverse arches of the foot that provide a rigid
propulsive lever and critical shock absorption during striding bipedal
gait. Evidence for arches in the earliest well-known Australopithecus
species, A. afarensis, has long been debated. A complete fourth metatarsal
of A. afarensis was recently discovered at Hadar, Ethiopia. It exhibits
torsion of the head relative to the base, a direct correlate of a
transverse arch in humans. The orientation of the proximal and distal ends
of the bone reflects a longitudinal arch. Further, the deep, flat base and
tarsal facets imply that its midfoot had no ape-like midtarsal break.
These features show that the A. afarensis foot was functionally like that
of modern humans and support the hypothesis that this species was a
committed terrestrial biped.

http://www.sciencemag.org/content/331/6018/750.abstract

--Laura

Stop the Press!! – A Pterosaur with an Egg 

http://www.sciencemag.org/content/331/6015/321.full

Junchang Lü, David M. Unwin, D. Charles Deeming, Xingsheng Jin, Yongqing Liu
and Qiang Ji

An Egg-Adult Association, Gender, and Reproduction in Pterosaurs

Science 21 January 2011:
Vol. 331 no. 6015 pp. 321-324
DOI: 10.1126/science.1197323

Abstract:

A sexually mature individual of Darwinopterus preserved together with an egg
from the Jurassic of China provides direct evidence of gender in pterosaurs
and insights into the reproductive biology of these extinct fliers. This new
find and several other examples of Darwinopterus demonstrate that males of
this pterosaur had a relatively small pelvis and a large cranial crest,
whereas females had a relatively large pelvis and no crest. The ratio of egg
mass to adult mass is relatively low, as in extant reptiles, and is
comparable to values for squamates. A parchment-like eggshell points to
burial and significant uptake of water after oviposition. This evidence for
low parental investment contradicts the widespread assumption that
reproduction in pterosaurs was like that of birds and shows that it was
essentially like that of reptiles.

--Mikko

News-flash: A new basal theropod from the Valley of the Moon 

Hi,

review: http://www.sciencemag.org/content/331/6014/134.full

article: http://www.sciencemag.org/content/331/6014/206.full

Ricardo N. Martinez, Paul C. Sereno, Oscar A. Alcober, Carina E. Colombi,
Paul R. Renne, Isabel P. Montañez and Brian S. Currie:
A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea.

Science 14 January 2011:
Vol. 331 no. 6014 pp. 206-210
DOI: 10.1126/science.1198467

--Mikko

News-flash: Ammonite lifestyles and structure 

Fresh information about ammonite lifestyles, diet, and structure.

http://www.sciencemag.org/content/331/6013/70.full

Isabelle Kruta, Neil Landman, Isabelle Rouget, Fabrizio Cecca and Paul
Tafforeau, 2011:
The Role of Ammonites in the Mesozoic Marine Food Web Revealed by Jaw
Preservation.
Science 7 January 2011: Vol. 331 no. 6013 pp. 70-72, DOI:
10.1126/science.1198793



--Mikko

Giant fossil bird found on ‘hobbit’ island of Flores

Fossils of the genus Leptoptilos from the Pleistocene of Liang Bua, Flores, Indonesia, belong to a new species of giant marabou stork, Leptoptilos robustus sp. nov. This giant bird, estimated at 1.80 m in length, was similar in dimensions to extant Leptoptilos dubius, except for the tibiotarsus.  An evolutionary lineage is proposed in which a volant L. dubius-like ancestor in the Middle Pleistocene evolved into the Late Pleistocene L. robustus on Flores, with a concomitant reduction of the ability to fly and an increase in body size. The large body size and terrestrial lifestyle of L. robustus are responses to an unbalanced, insular environment with abundant prey items and a lack of mammalian carnivores, and emphasize the extraordinary nature of the Homo floresiensis fauna.

In the news:

http://news.bbc.co.uk/earth/hi/earth_news/newsid_9261000/9261713.stm

The paper:

http://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.2010.00616.x/full