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Earliest evidence for parental care in Synapsida (and Amniota)



Botha-Brink, J. & S.P. Modesto. 2007. A mixed-age classed 'pelycosaur'
aggregation from South Africa: earliest evidence of parental care in
amniotes? Proc. R. Soc. B. doi:10.1098/rspb.2007.0803 (FirstCite).

Abstract
Living species of mammals, crocodiles and most species of birds exhibit
parental care, but evidence of this
behaviour is extremely rare in the fossil record. Here, we present a new
specimen of varanopid 'pelycosaur'
from the Middle Permian of South Africa. The specimen is an aggregation,
consisting of five articulated
individuals preserved in undisturbed, close, lifelike, dorsal-up,
subparallel positions, indicating burial in
'life position'. Two size classes are represented. One is 50% larger than
the others, is well ossified, has fused
neurocentral sutures and is distinguished by a coat of dermal ossifications
that covers the neck and
shoulder regions.We regard this individual to be an adult. The remaining
four skeletons are considered to
be juveniles as they are approximately the same size, are poorly ossified,
have open neurocentral sutures
and lack dermal ossifications. Aggregates of juvenile amniotes are usually
siblings. Extant analogues of
adult and juvenile groupings suggest that the adult is one of the parents,
leading us to regard the
aggregation as a family group. The Late Middle Permian age of the varanopid
family predates the
previously known oldest fossil evidence of parental care in terrestrial
vertebrates by 140 Myr.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA