VICARIANCE AND *THAT* ANKYLOSAUR

["Darren Naish" <dwn194@soton.ac.uk>]

Guess it helps if you look in the correct journal.. Walter Coombs,
together with Thomas Demere, describes a Nodosauridae _incertae sedis_
in:

COOMBS, W.P. and DEMERE, T.A. 1996. A late Cretaceous nodosaurid
dinosaur (Dinosauria: Ornithischia) from marine sediments of coastal
California. _Journal of Paleontology_ 70 (2): 311-326

The partial skeleton consists primarily of ilia, hindlimbs, posterior
dorsal armour, and partial forelimb elements and additional
armour. It's late Campanian and from north of San Diego. There are
similarities with _Panoplosaurus_, _Edmontonia_ and what's known of
_Stegopelta landerensis_, but unfortunately 'skeletal elements
critical for generic determination are not preserved, and the specimen
is identified as Nodosauridae, incertae sedis.'. That this is another
nodosaur found in marine sediments is interesting (I believe the same
is true of _Niobrarasaurus_, amongst others - _Pawpawsaurus_ too?),
and it's stated that 'nodosaurids had broad ecological tolerances, and
visited riparian and coastal environments more frequently than other
dinosaurs.'. The armour scutes of the animal, while its carcass rested
on the sea floor, provided a substrate for molluscs and other fauna,
and anocoracid sharks had scavenged on the carcass.

HEDGES, S.B., PARKER, P.H., SIBLEY. C.G. and KUMAR,
S. 1996. Continental breakup and the ordinal diversification of birds
and mammals. _Nature_ 381: 226-229

By using that old chestnut: estimating divergence times using
constantly evolving sets of genes, Hedges et al propose that extant
bird and mammal Orders are older than generally supposed: in general,
first diverging sometime in the latter half of the Cretaceous. They
suggest that divergences occurred during Cretaceous continental
breakup and that this mechanism was more crucial to generation of
Orders than was the 'filling of the barrel' after the K-T event.  This
is obviously a view consistent with the bird phylogeny work Sibley and
his colleagues have published: their time lines have modern Orders
originated in the Upper Cretaceous, and it isn't in agreement with
what the more palaeontologically-minded often support (e.g. Feduccia
insists that extant Orders are essentially post-Oliogocene
novelties). The debate will continue, but I doubt if the same hard and
fast rules apply to all the taxa involved.

And finally..

MOURER-CHAUVIRE, C., SENUT, B., PICKFORD, M. and MEIN, P. 1996. Le
plus ancien representant de genre _Struthio_ (Aves, Struthionidae), du
Miocene inferieur de Namibie. _Comptes Rendu Acad. Sci. Paris_ 322
serie II a: 325-332

Ostriches have an interesting fossil history, and reported here is the
most primitive of the genus _Struthio_, the new species
_S. coppensi_. It would have been smaller and more gracile than modern
ostriches, but like them was didactyl.  Other fossil ostriches are of
the same size or bigger than the extant species, _S. camelus_: various
Plio-Pleistocene forms, _S. brachydactylus_ and _S, asiaticus_ in
particular, are massive birds. _S. coppensi_ shows that ostriches are
a bit older than usually thought: early representatives were probably
Oligocene (how this relates to the above work - especially if you
consider anything of the controversies surrounding ratite evolution -
I dread to think).  Until I read this paper, I didn't know that
ostriches have lost digit 2 (I thought 4 was the missing one).

A family of ducks is trapped in our courtyard.

"P--l--e--a--s--e  d--o---n--'t  e--a--t  m---e--e"

DARREN NAISH
dwn194@soton.ac.uk