Re: Psittacosaurus juvenile herd behavior

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

Since this has not been commented on on the DML (it's mentioned on
some blogs), I would point out an important fact revealed in this
paper--the fossil nest of psittacosaurs with a cluster of juveniles
"guarded" by an adult is in fact a fake (shades of Archaeoraptor!).
This doctored fossil find is cited in various places as supposed
evidence of direct parental care in dinosaurs.


"Our close inspection of this cluster of 34 juveniles (DNHM D2156)
shows that the ‘adult’ skull has been added with glue, and so was not
part of the original specimen; there is no sedimentary connection to
the main slab below, and the skull rests loosely on top of that slab,
and is not in any way part of the sedimentary layer in which the
juveniles all occur, intertwined with each other. The evidence is that
the ‘adult’ skeleton just contains a few postcranial bones without any
articulation, and the skull position is much higher than the juvenile
bone-bed plane. The juveniles all seem to belong together because they
are preserved at one level in the rock, and their limbs and tails
overlap each other in complex ways."



On Wed, May 15, 2013 at 8:31 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
>
>
> A new online open-access paper:
>
>
> Qi Zhao, Michael J. Benton, Xing Xu, and Martin J. Sander (2013)
> Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur
> Psittacosaurus.
> Acta Palaeontologica Polonica (in press)
> doi: http://dx.doi.org/10.4202/app.2012.0128
> http://app.pan.pl/article/item/app20120128.html
>
>
> It has hitherto been hard to prove that any association of juvenile
> dinosaurs represents original behaviour rather than sedimentary
> accumulation, and it has been hard also to determine the ages of such
> juveniles. A previously described specimen, which consists of an
> ‘adult’ Psittacosaurus with 34 fully articulated juveniles, turns out
> to be a composite: the ‘adult’ skull has been added, and in any case
> it is below breeding age. Other juvenile-only clusters have been
> reported, but the best examples that likely reflect behaviour rather
> than sedimentary accumulation are specimens from the Early Cretaceous
> Lujiatun beds in NE China, which were entombed beneath pyroclastic
> flow deposits. A remarkable juvenile-only cluster of Psittacosaurus
> shows clear evidence of different ages (five 2-year olds and one
> 3-year old) based on bone histological analysis. These juveniles may
> have associated together as a close knit, mixed-age herd either for
> protection, to enhance their foraging, or as putative helpers at the
> parental nest.