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Cretaceous turtle tracks from China + origin of bird feather pigments and zygodactyly

Ben Creisler

Some non-dino papers that may be of interest:

Lida Xing, Marco Avanzini, Martin G. Lockley, Tetsuto Miyashita,
Hendrik Klein, Jianping Zhang, Qing He, Liqi Qi, Julien D. Divay, and
Chengkai Jia (2014)
Early Cretaceous turtle tracks and skeletons from the Junggar Basin,
Xinjiang, China.
Palaios 9(4): 137–144
doi: http://dx.doi.org/10.2110/palo.2014.012

A high density of tracks resembling both the ichnogenera Chelonipus
and Emydhipus occurs on surfaces of the Lower Cretaceous Tugulu Group
at the Huangyangquan tracksite in Wuerhe district (Xinjiang Uyghur
Autonomous Region, northwestern China). These ichnotaxa are especially
known from Central Europe where they have been found in Triassic and
Upper Jurassic–Lower Cretaceous deposits. Tracks are highly variable
in morphology due to having been made while walking and swimming over
soft substrates. Nevertheless they are diagnostic of turtle
trackmakers and are readily distinguished from those of other aquatic
vertebrates such as crocodilians and from those of pterosaurs.
Abundant turtle body fossils occur in the region helping to provide
strong support for this interpretation. The record enlarges our
knowledge of turtles, their environment and distribution in the Early
Cretaceous of China.


Daniel B. Thomas, Kevin J. McGraw, Michael W. Butler, Matthew T.
Carrano, Odile Madden and Helen F. James (2014)
Ancient origins and multiple appearances of carotenoid-pigmented
feathers in birds.
Proceedings of the Royal Society B 7 August 2014 vol. 281 no. 1788 20140806
doi: 10.1098/rspb.2014.0806

The broad palette of feather colours displayed by birds serves diverse
biological functions, including communication and camouflage. Fossil
feathers provide evidence that some avian colours, like black and
brown melanins, have existed for at least 160 million years (Myr), but
no traces of bright carotenoid pigments in ancient feathers have been
reported. Insight into the evolutionary history of plumage carotenoids
may instead be gained from living species. We visually surveyed modern
birds for carotenoid-consistent plumage colours (present in 2956 of
9993 species). We then used high-performance liquid chromatography and
Raman spectroscopy to chemically assess the family-level distribution
of plumage carotenoids, confirming their presence in 95 of 236 extant
bird families (only 36 family-level occurrences had been confirmed
previously). Using our data for all modern birds, we modelled the
evolutionary history of carotenoid-consistent plumage colours on
recent supertrees. Results support multiple independent origins of
carotenoid plumage pigmentation in 13 orders, including six orders
without previous reports of plumage carotenoids. Based on time
calibrations from the supertree, the number of avian families
displaying plumage carotenoids increased throughout the Cenozoic, and
most plumage carotenoid originations occurred after the Miocene Epoch
(23 Myr). The earliest origination of plumage carotenoids was
reconstructed within Passeriformes, during the Palaeocene Epoch (66–56
Myr), and not at the base of crown-lineage birds.

João Francisco Botelho, Daniel Smith-Paredes, Daniel Nuñez-Leon,
Sergio Soto-Acuña, and Alexander O. Vargas (2014)
The developmental origin of zygodactyl feet and its possible loss in
the evolution of Passeriformes.
Proceedings of the Royal Society B 7 August 2014 vol. 281 no. 1788 20140765
doi: 10.1098/rspb.2014.0765

The zygodactyl orientation of toes (digits II and III pointing
forwards, digits I and IV pointing backwards) evolved independently in
different extant bird taxa. To understand the origin of this trait in
modern birds, we investigated the development of the zygodactyl foot
of the budgerigar (Psittaciformes). We compared its muscular
development with that of the anisodactyl quail (Galliformes) and show
that while the musculus abductor digiti IV (ABDIV) becomes strongly
developed at HH36 in both species, the musculus extensor brevis digiti
IV (EBDIV) degenerates and almost disappears only in the budgerigar.
The asymmetric action of those muscles early in the development of the
budgerigar foot causes retroversion of digit IV (dIV). Paralysed
budgerigar embryos do not revert dIV and are anisodactyl. Both
molecular phylogenetic analysis and palaeontological information
suggest that the ancestor of passerines could have been zygodactyl. We
followed the development of the zebra finch (Passeriformes) foot
muscles and found that in this species, both the primordia of the
ABDIV and of the EBDIV fail to develop. These data suggest that loss
of asymmetric forces of muscular activity exerted on dIV, caused by
the absence of the ABDIV, could have resulted in secondary
anisodactyly in Passeriformes.