Saturday, December 31, 2011

2011 in Paleontology

Fig 1.- A selection of species described in 2011.

It’s time for a retrospective of year 2011 in the paleontological field. Besides the description and discovery of new species, here is my pick of the top stories that marked the year:


150th anniversary of the description of Archaeopteryx

2011 is a fitting anniversary year for Archaeopteryx with the unveiling of the 11th specimen, the ICZN decision to make the London skeleton the new type for the genus (originally based on a single feather). The systematic position of the transitional fossil is still uncertain with two papers challenging its place at the base of the avialian tree while another puts it back on. An attempt has also been made to reconstruct the color of the London holotype feather.
Fig. 2.- Archaeopteryx.

References:
R. Carney, J. Vinther, M. Shawkey, L. d’Alba & J. Ackermann. 2011. Black Feather Color in Archaeopteryx. 2011 Society of Vertebrate Paleontology Annual Meeting Abstracts, p 84.

Michael S. Y. Lee & Trevor H. Worthy. 2011. Likelihood reinstates Archaeopteryx as a primitve bird. Biology letters. Published online before print.

Darren Naish, Gareth Dyke, Andrea Cau, François Escuillié and Pascal Godefroit. 2011. A gigantic bird from the Upper Cretaceous of Central Asia. Biology Letters. Published online before print. Electronic supplementary info.

Xing Xu, Hailu You, Kai Du and Fenglu Han. 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475: 465–470.

ICZN. 2011. OPINION 2283 (Case 3390) Archaeopteryx lithographica von Meyer, 1861 (Aves): conservation of usage by designation of a neotype. Bulletin of Zoological Nomenclature 68 (3): 230–233.

Fig 3.- Polycotylus giving live birth.

Plesiosaur viviparity

The discovery of a fossil plesiosaur (Polycotylus) with a well-developed fetus in its womb strongly suggests that these marine reptiles were giving live birth.

Reference: O'Keefe, F.R.; and Chiappe, L.M. 2011. Viviparity and K-selected life history in a Mesozoic marine plesiosaur (Reptilia, Sauropterygia). Science 333 (6044): 870–873.

Fig 4.- Velociraptor captured with an IR camera.

Theropods were nocturnal

The analysis of scleral rings of many extinct taxa suggests that most theropods and some pterosaurs hunted at nights whereas the herbivorous dinosaurs were mostly diurnal.

Reference: Schmitz, L. and  Motani R. 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology. Science 332, 705.

Fig 5.- Microraptor.

Microraptor ate birds

We already knew that the four-winged dromaeosaur Microraptor was eating small mammals but a new gut content study of one specimen of this dinosaur shows that it also fed on birds.

Reference: O’Connor, Zhou & Xu. 2011. Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds. PNAS.

Fig 6.- Deinonychus.

A new model for Deinonychus predatory behavior

Deinonychus might have use its powerful claws to pinned down its prey in a manner similar to modern day eagles.

References: Fowler, D. W.; Freedman, E. A.; Scannella, J. B.; Kambic, R. E. 2011. The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds. PLoS ONE 6 (12): e28964.

Fig 7.- Eodromaeus.

Eodromaeus murphi, the earliest theropod?

This little critter might be the earliest and most primitive theropod to date, if indeed Eoraptor is reclassified as a basal sauropodomorph.

Reference: R. N. Martinez, P. C. Sereno, O. A. Alcober, C. E. Colombi, P. R. Renne, I. P. Montañez, and B. S. Currie. 2011. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science 331(6014):206-210.
Fig 8.- Camarasaurus herd.

Teeth gave proof of Camarasaurus seasonal migration

… and apparently they traveled quite a long distance in search of food. The technique of teeth analysis for isotopic content shows lots of promise for understanding behavior of creatures long gone.

Reference: H. C. Fricke, J.Hencecroth, M.E. Hoerner. 2011. Lowland–upland migration of sauropod dinosaurs during the Late Jurassic epoch. Nature. Advanced online publication.
Fig 9.- Diania.

Diania, the “walking cactus”

The Lower Cambrian Diania cactiformis is the first fossil of lobopod with jointed legs, and therefore a possible missing link to the Arthropods.

Reference:  Jianni Liu, Michael Steiner, Jason A. Dunlop, Helmut Keupp, Degan Shu, Qiang Ou, Jian Han, Zhifei Zhang & Xingliang Zhang. 2011. An armoured Cambrian lobopodian from China with arthropod-like appendages. Nature. 470, 526–530.

Fig 10.- Juramaia.

Juramaia sinensis, the first eutherian

Juramaia from the Middle Jurassic of Liaoning, China, dislodged Eomaia from the Early Cretaceous as the first known placental mammal.

Reference: Z.-X. Luo, C.-X. Yuan, Q.-J. Meng and Q. Ji. 2011. A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476:442-445.

Fig 11.- Shastasaurus.

Shastasaurus may have been a suction feeder

The giant ichthyosaurs of the Late Triassic might indeed have been specialized feeder that preyed on squids.

Reference: Sander PM, Chen X, Cheng L, Wang X (2011) Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs. PLoS ONE 6(5): e19480.
Fig 12.- Cryptolacerta.

Cryptolacerta hassiaca, the most primitive worm lizard

The modern amphisbaenians are burrowing limbless creatures that superficially resemble earthworms, but Cryptolacerta confirm their link to lizards.

Reference: Müller J., Hipsley C.A., Head J.J., Kardjilov N., Hilger A., Wuttke M. & reisz R.R. 2011. Eocene lizard from Germany reveals amphisbaenian origins. Nature 473, 364-367.

Fig 13.- The Triassic Kraken.

The Artsy Kraken

And finally, 2011 was marked by one outrageous claim about giant cephalopods playing with giant ichthyosaur bones.

Happy New Year 2012, Folks!

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

3 comments:

  1. I voted for the Kraken because of how hilarious that whole debacle was. My serious pick would of been either Plesiosaur live birth or the first eutherian

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  2. RPR has my vote! With Archaeoperyx's black coverts in a close second. (What, no J. palmapenis? Aw...)

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  3. I vote for Eodromaeus murphi as my favorite one.

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