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A Production of

Morganucodon oehleriFossil, Fossil Mammaliaform
Dr. Timothy Rowe - The University of Texas at Austin
Dr. Thomas Macrini, Dr. Zhe-Xi Luo
Morganucodon oehleri
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skull
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Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (IVPP 8685)

Image processing: Dr. Jessie Maisano
Image processing: Dr. Ted Macrini
Publication Date: 30 Jan 2003

ITIS TNS Google MSN

Abstract from Rowe, T., Macrini, T.E., and Luo, Z.-X. 2011. Fossil evidence on origin of the mammalian brain (Science, 332, 955-957):

Many hypotheses have been postulated regarding the early evolution of the mammalian brain. Here, X-ray tomography of the Early Jurassic mammaliaforms Morganucodon and Hadrocodium sheds light on this history. We found that relative brain size expanded to mammalian levels, with enlarged olfactory bulbs, neocortex, pyriform cortex, and cerebellum, in two evolutionary pulses. The initial pulse was probably driven by increased resolution in olfaction and improvements in tactile sensitivity (from body hair) and neuromuscular coordination. A second pulse of olfactory enhancement then enlarged the brain to mammalian levels. The origin of crown Mammalia saw a third pulse of olfactory enhancement, with ossified ethmoid turbinals supporting an expansive olfactory epithelium in the nasal cavity, allowing full expression of a huge odorant receptor genome.

*Click the Additional Imagery tab for endocast animations.

About the Species

This specimen was collected from the Hettangian-Sinomurian Formation (Early Jurassic) in the Lufeng Basin of Junan, P.R. China. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. A. W. Crompton of the Museum of Comparative Zoology, Harvard University, and Dr. Zhe-Xi Luo of the Carnegie Museum of Natural History.

About this Specimen

This specimen was scanned on by Richard Ketcham and Matthew Colbert 21 April 1999. It was scanned along the coronal axis for a total of 446 slices. Slice thickness is 0.096 mm with an interslice spacing of 0.072 mm (for a slice overlap of 0.024 mm).

About the
Scan

Literature
Gauthier J., A.G. Kluge, and T. Rowe. 1988. Amniote phylogeny and the importance of fossils. Cladistics 4:105-210.

Kermack, K.A. 1963. The cranial structure of the triconodonts. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 246:83-103.

Kermack K.A., F. Mussett, and H.W. Rigney. 1981. The skull of Morganucodon. Zoological Journal of the Linnean Society 71:1-158.

Luo, Z., A.W. Crompton, and S.G. Lucas. 1995. Evolutionary origins of the mammalian promontorium and cochlea. Journal of Vertebrate Paleontology 15:113-121.

Rougier, G.W., J.R. Wible, and J.A. Hopson. 1996. Basicranial anatomy of Priacodon fruitaensis (Triconodontidae, Mammalia) from the late Jurassic of Colorado, and a reappraisal of mammaliaform interrelationships. American Museum Novitates 3183:1-38.

Rowe, T. 1996. Coevolution of the mammalian middle ear and neocortex. Science 273:651-654.

Literature
& Links
endocast pitch movie

Click on the thumbnail to the left for a pitch animation (1.2 mb) of the isolated Morganucodon cranial endocast.

endocast rollmovie

Click on the thumbnail to the left for a roll animation (1.3 mb) of the isolated Morganucodon cranial endocast.

Additional
Imagery

To cite this page: Dr. Timothy Rowe, Dr. Thomas Macrini, Dr. Zhe-Xi Luo, 2003, "Morganucodon oehleri" (On-line), Digital Morphology. Accessed October 23, 2014 at http://digimorph.org/specimens/Morganucodon_oehleri/.

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