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Fw: my gastrolith research results are online now

Apologies if this has already been posted here.


--------- Forwarded message ----------
From: Oliver Wings <oliver.wings@web.de>
To: Vert-Paleo Mailing List <vrtpaleo@usc.edu>

Dear all,
I promised to some of you to let you know when the PDF version of my

Wings, O., 2004. Identification, distribution, and function of
gastroliths in dinosaurs and extant birds with emphasis on ostriches
(Struthio camelus). Ph.D. Thesis, University of Bonn, Bonn, 187 pp.

has been put online, and this day has finally come.

For those of you who do not want to wait for the peer-reviewed papers,
please download the complete thesis here:
respectively here (English website, the files are the same):

I recommend to download the thesis in the one-file-version because this
version also contains bookmarks of all chapters/headlines which makes it
much easier to navigate when reading on the screen.

Best regards,

PS: Here is the abstract:

Gastroliths (stomach stones) are known from many extinct and extant
vertebrate clades and are potentially useful for paleobiological
interpretations. This dissertation investigates the identification,
function, distribution, and taphonomy of gastroliths with a focus on
those of dinosaurs, including extant birds.

The terms bio-gastroliths, patho-gastroliths, and geo-gastroliths are
suggested as more precise descriptions involving the origin of the
stones. A review of the literature reveals that trituration and mixing of
ingesta is an accepted function of gastroliths in many vertebrates
(particularly in birds), whereas the influence of gastroliths on buoyancy
in aquatic animals appears to be negligible. Accidental ingestion of
sediment is considered to be common, as is the overlap of numerous

The results of a study on German (n=135) and South African (n=212)
free-ranging farm ostriches (Struthio camelus) indicate that ostriches
ingest stones of greatly varying size. Adult animals typically hold one
kilogram of stones in their stomach. On average, each stomach contained
several thousand gastroliths with a grain size >1 mm. The mean gastrolith
mass is very similar in both populations and constitutes about 1% of the
mean body mass. Gastrolith mass is not significantly correlated with
gender, age, season, and food contents by weight. Quartz is the
predominating mineral type among ostrich gastroliths.

The taphonomic processes that may lead to the loss of gastroliths are
discussed and the fossil record of the most important groups of
lithophagic vertebrates (tangasaurids, crocodilians, sauropodomorph and
theropod dinosaurs including birds) is reviewed. Experimental results
show that gastroliths can be set free from ostrich chick carcasses with a
body weight <12 kg after relatively short periods (3-6 days) in a hot and
arid climate and that a separation in an aquatic environment is likely
caused by prolonged floating of the carcass. A new classification of
gastroliths is introduced that scales their presumed authenticity. The
scale ranges from 1 (cluster of stones in the abdominal area of the
skeleton) to 6 (surface finds of isolated, rounded and occasionally
polished stones without associated bones).

Sedimentological and taphonomic evidence from several classic Upper
Jurassic sauropod dinosaur localities shows that there are very few
sauropod finds with unambiguous gastroliths. The scarcity of stones in
the fine-grained sediments of most of these localities suggests that only
a small number of sauropods possessed gastroliths. The occurrence of a
gastric mill as seen in birds is not supported by the taphonomic evidence
for sauropods. Without an association with fossil bone, there is no
convincing evidence that exotic stones (exoliths) represent former
gastroliths. It is more plausible that most of the surface-collected
exoliths are weathering relicts of stratigraphically younger conglomerate

An experiment was conducted that simulated a bird gastric mill in a rock
tumbler using stones, water, plant material (grass), hydrochloric acid,
and pepsin. The forces and the abrasion rate in the artificial gizzard
were lower than in a real ostrich gizzard. After the end of the
experiment six months later, the stones exhibited a total weight loss of
22.4%. Stomach juices and phytoliths contained in the grass had no
visible effect on stone surface development. Given that no polish formed
due to continuous abrasion, other causes, such as wind abrasion and
diagenesis, should be considered for the polish sometimes observed on
fossil gastroliths.

Finally, future research on gastroliths in crocodilians, pinnipeds,
Permian tangasaurids, insectivorous species (e.g., anteaters) and other
taxa is suggested. The distribution of gastroliths in extant and fossil
members of Dinosauria is listed in appendices.

Oliver Wings (Dipl.-Geol.)
Niedersaechsisches Landesmuseum Hannover - Naturkundeabteilung
Willy-Brandt-Allee 5
D - 30169 Hannover
Phone: +49 (0)511 9807830
Fax:    +49 (0)511 9807880
E-mail:  oliver.wings@web.de

Official website: http://www.nlmh.de
Private websites: http://go.to/gastrolith

Check out our current dinosaur trackway dig:

Current research topics:
Gastroliths, Bone Diagenesis, Vertebrate Taphonomy