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Science. 2014 Sep 26;345(6204):1613-6. doi: 10.1126/science.1258750. Epub 2014 Sep 11.

Semiaquatic adaptations in a giant predatory dinosaur.

Author information

1
Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA. nibrahim@uchicago.edu.
2
Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
3
Museo di Storia Naturale di Milano, Corso Venezia 55, 20121 Milan, Italy.
4
School of Earth Sciences, University of Bristol, Queen's Road, Bristol, BS8 1RJ, UK.
5
School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Road, Portsmouth, PO1 3QL, UK.
6
Laboratoire de Géosciences, Faculté des Sciences Aïn Chock, Université Hassan II, Casablanca, Morocco.
7
Intellectual Ventures, 3150 139th Avenue Southeast, Bellevue, WA 98005, USA.
8
Dipartimento di Scienze della Terra, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy.

Abstract

We describe adaptations for a semiaquatic lifestyle in the dinosaur Spinosaurus aegyptiacus. These adaptations include retraction of the fleshy nostrils to a position near the mid-region of the skull and an elongate neck and trunk that shift the center of body mass anterior to the knee joint. Unlike terrestrial theropods, the pelvic girdle is downsized, the hindlimbs are short, and all of the limb bones are solid without an open medullary cavity, for buoyancy control in water. The short, robust femur with hypertrophied flexor attachment and the low, flat-bottomed pedal claws are consistent with aquatic foot-propelled locomotion. Surface striations and bone microstructure suggest that the dorsal "sail" may have been enveloped in skin that functioned primarily for display on land and in water.

PMID:
25213375
DOI:
10.1126/science.1258750
[Indexed for MEDLINE]
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