Author Archives: LS

Carbonemys cofrinii

This is what happens when you don’t subscribe to Journal of Systematic Paleontology and you don’t check in with twitter!

“New pelomedusoid turtles from the late Palaeocene Cerrejon Formation of Colombia and their implications for phylogeny and body size evolution”

Authors: Edwin Cadena, Dan Ksepka, North Carolina State University; Carlos Jaramillo, Smithsonian Tropical Research Institute, Panama; Jonathan Bloch, Florida Museum of Natural History

Published: In the Journal of Systematic Palaeontology

http://www.tandfonline.com/doi/abs/10.1080/14772019.2011.569031
http://news.ncsu.edu/releases/cadena-turtle/

Jackie

Did Neandertals Paint Early Cave Art?

U-Series Dating of Paleolithic Art in 11 Caves in Spain

Paleolithic cave art is an exceptional archive of early human symbolic behavior, but because obtaining reliable dates has been difficult, its chronology is still poorly understood after more than a century of study. We present uranium-series disequilibrium dates of calcite deposits overlying or underlying art found in 11 caves, including the United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage sites of Altamira, El Castillo, and Tito Bustillo, Spain. The results demonstrate that the tradition of decorating caves extends back at least to the Early Aurignacian period, with minimum ages of 40.8 thousand years for a red disk, 37.3 thousand years for a hand stencil, and 35.6 thousand years for a claviform-like symbol. These minimum ages reveal either that cave art was a part of the cultural repertoire of the first anatomically modern humans in Europe or that perhaps Neandertals also engaged in painting caves.

http://news.sciencemag.org/sciencenow/2012/06/did-neandertals-paint-early-cave.html

http://www.sciencemag.org/content/336/6087/1409

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Laura

How to weigh dinosaurs (and mammals) with lasers

Minimum convex hull mass estimations of complete mounted skeletons

Body mass is a critical parameter used to constrain biomechanical and physiological traits of organisms. Volumetric methods are becoming more common as techniques for estimating the body masses of fossil vertebrates. However, they are often accused of excessive subjective input when estimating the thickness of missing soft tissue. Here, we demonstrate an alternative approach where a minimum convex hull is derived mathematically from the point cloud generated by laser-scanning mounted skeletons. This has the advantage of requiring minimal user intervention and is thus more objective and far quicker. We test this method on 14 relatively large-bodied mammalian skeletons and demonstrate that it consistently underestimates body mass by 21 per cent with minimal scatter around the regression line. We therefore suggest that it is a robust method of estimating body mass where a mounted skeletal reconstruction is available and demonstrate its usage to predict the body mass of one of the largest, relatively complete sauropod dinosaurs: Giraffatitan brancai (previously Brachiosaurus) as 23200 kg.

http://rsbl.royalsocietypublishing.org/content/early/2012/06/04/rsbl.2012.0263.abstract

More on the subject:

http://blogs.discovermagazine.com/notrocketscience/2012/06/05/weigh-dinosaur-with-lasers/

And of course the ‘sensational reporting’:

http://www.huffingtonpost.co.uk/2012/06/05/dinosaurs-lighter-than-previously-thought_n_1570073.html

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Laura

Eocene primate from Myanmar and the initial anthropoid colonization of Africa

Late Middle Eocene primate from Myanmar and the initial anthropoid colonization of Africa

Reconstructing the origin and early evolutionary history of anthropoid primates (monkeys, apes, and humans) is a current focus of paleoprimatology. Although earlier hypotheses frequently supported an African origin for anthropoids, recent discoveries of older and phylogenetically more basal fossils in China and Myanmar indicate that the group originated in Asia. Given the Oligocene-Recent history of African anthropoids, the colonization of Africa by early anthropoids hailing from Asia was a decisive event in primate evolution. However, the fossil record has so far failed to constrain the nature and timing of this pivotal event. Here we describe a fossil primate from the late middle Eocene Pondaung Formation of Myanmar, Afrasia djijidae gen. et sp. nov., that is remarkably similar to, yet dentally more primitive than, the roughly contemporaneous North African anthropoid Afrotarsius. Phylogenetic analysis suggests that Afrasia and Afrotarsius are sister taxa within a basal anthropoid clade designated as the infraorder Eosimiiformes. Current knowledge of eosimiiform relationships and their distribution through space and time suggests that members of this clade dispersed from Asia to Africa sometime during the middle Eocene, shortly before their first appearance in the African fossil record. Crown anthropoids and their nearest fossil relatives do not appear to be specially related to Afrotarsius, suggesting one or more additional episodes of dispersal from Asia to Africa. Hystricognathous rodents, anthracotheres, and possibly other Asian mammal groups seem to have colonized Africa at roughly the same time or shortly after anthropoids gained their first toehold there.

http://www.pnas.org/content/early/2012/05/29/1200644109.abstract

http://www.livescience.com/20738-primate-fossil-origins-asia.html

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Laura

Birds have paedomorphic dinosaur skulls

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11146.html

Birds have paedomorphic dinosaur skulls

Bhart-Anjan S. Bhullar, Jesús Marugán-Lobón, Fernando Racimo, Gabe S. Bever,     Timothy B. Rowe, Mark A. Norell     & Arhat Abzhanov

The interplay of evolution and development has been at the heart of evolutionary theory for more than a century1. Heterochrony—change in the timing or rate of developmental events—has been implicated in the evolution of major vertebrate lineages such as mammals2, including humans1. Birds are the most speciose land vertebrates, with more than 10,000 living species3 representing a bewildering array of ecologies. Their anatomy is radically different from that of other vertebrates. The unique bird skull houses two highly specialized systems: the sophisticated visual and neuromuscular coordination system4, 5 allows flight coordination and exploitation of diverse visual landscapes, and the astonishing variations of the beak enable a wide range of avian lifestyles. Here we use a geometric morphometric approach integrating developmental, neontological and palaeontological data to show that the heterochronic process of paedomorphosis, by which descendants resemble the juveniles of their ancestors, is responsible for several major evolutionary transitions in the origin of birds. We analysed the variability of a series of landmarks on all known theropod dinosaur skull ontogenies as well as outgroups and birds. The first dimension of variability captured ontogeny, indicating a conserved ontogenetic trajectory. The second dimension accounted for phylogenetic change towards more bird-like dinosaurs. Basally branching eumaniraptorans and avialans clustered with embryos of other archosaurs, indicating paedomorphosis. Our results reveal at least four paedomorphic episodes in the history of birds combined with localized peramorphosis (development beyond the adult state of ancestors) in the beak. Paedomorphic enlargement of the eyes and associated brain regions parallels the enlargement of the nasal cavity and olfactory brain in mammals6. This study can be a model for investigations of heterochrony in evolutionary transitions, illuminating the origin of adaptive features and inspiring studies of developmental mechanisms.

– Jacqueline

Some interesting new papers

Here are a few very recent papers that might be of interest to the club members:

Using paleontological data to assess mammalian community structure: Potential aid in conservation planning

http://www.sciencedirect.com/science/article/pii/S0031018212002234

Analysis of Dental Root Apical Morphology: A New Method for Dietary Reconstructions in Primates

http://onlinelibrary.wiley.com/doi/10.1002/ar.22482/full

New evidence for canine dietary function in Afropithecus turkanensis

http://www.sciencedirect.com/science/article/pii/S0047248412000437

New insight from old bones: stable isotope analysis of fossil mammals

http://www.bioone.org/doi/abs/10.1644/11-MAMM-S-179.1

-Laura