Gizzard vs. teeth; Hungarian dinos and birds; Ceresiosaurus bone growth

[bh480@scn.org]

From: Ben Creisler
bh480@scn.org

A number of recent papers:

Julia Fritz, Ellen Kienzle, Jürgen Hummel, Oliver Wings, 
W. Jürgen Streich, and Marcus Clauss (2011)
Gizzard vs. teeth, it's a tie: food-processing efficiency 
in herbivorous birds and mammals and implications for 
dinosaur feeding strategies.
Paleobiology 37(4):577-586. 2011 
doi: 10.1666/10031.1 
http://www.bioone.org/doi/abs/10.1666/10031.1

Abstract
Particle size reduction is a primary means of improving 
efficiency in herbivores. The mode of food particle size 
reduction is one of the main differences between 
herbivorous birds (gizzard) and mammals (teeth). For a 
quantitative comparison of the efficiency of food 
comminution, we investigated mean fecal particle sizes 
(MPS) in 14 herbivorous bird species and compared these 
with a data set of 111 non-ruminant herbivorous mammal 
species. In general MPS increased with body mass, but 
there was no significant difference between birds and 
mammals, suggesting a comparable efficiency of food 
processing by gizzards and chewing teeth. The results 
lead to the intriguing question of why gizzard systems 
have evolved comparatively rarely among amniote 
herbivores. Advantages linked to one of the two food 
comminution systems must, however, be sought in different 
effects other than size reduction itself. In 
paleoecological scenarios, the evolution of "dental 
batteries," for example in ornithopod dinosaurs, should 
be considered an advantage compared to absence of 
mastication, but not compared to gizzard-based herbivory.

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Attila Osi and Eric Buffetaut (2011)
Additional non-avian theropod and bird remains from the 
early Late Cretaceous (Santonian) of Hungary and a review 
of the European abelisauroid record.
Annales de Paléontologie (advance online publication)
doi:10.1016/j.annpal.2011.07.001
http://www.sciencedirect.com/science/article/pii/S07533969
11000346

Abstract
Hitherto unpublished remains of non-avian and avian 
theropods from the Late Cretaceous (Formation Csehbánya, 
Santonian) Iharkútlocality (western Hungary) are 
described. Non-avian theropod remains include an 
abelisaurid femur, which confirms the presence of this 
theropod family at Iharkút, and a metacarpal and a 
tibiotarsus from a paravian which may belong to 
Pneumatoraptor fodori, previously described from Iharkút. 
Birds are represented by two femora which clearly belong 
to enantiornithines, possibly to Bauxitornis, previously 
described from Iharkút. The abelisauroid record from the 
Cretaceous of Europe is reviewed.

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Jasmina Hugi (2011)
The long bone histology of Ceresiosaurus (Sauropterygia, 
Reptilia) in comparison to other eosauropterygians from 
the Middle Triassic of Monte San Giorgio 
(Switzerland/Italy).
Swiss Journal of Palaeontology (advance online 
publication)
DOI: 10.1007/s13358-011-0023-6 
http://www.springerlink.com/content/k78627100v15k703/

Ceresiosaurus is a secondarily marine reptile that lived 
during the Middle Triassic (Ladinian-Anisian) in a 
subtropical lagoonal environment with varying open marine 
influences. The genus comprises two species, 
Ceresiosaurus calcagnii and C. lanzi, and represents one 
of the largest vertebrate of up to 3-m snout-tail length 
from the UNESCO World Heritage site Monte San Giorgio, 
which is settled along the Swiss?Italian border. Earlier 
morphological studies identified this genus as basal 
sauropterygian still possessing many similarities with 
the plesiomorphic ancestral terrestrial condition. 
Interspecific morphological variation was interpreted as 
indicator for different habit(at) preferences by 
ascribing two locomotion types for each of the species. 
In this study, detailed data on the microstructure of the 
long bones are given and findings were put into a 
palaeoecological and phylogenetic context in comparison 
to other sauropterygians from Monte San Giorgio. Results 
showed that both Ceresiosaurus species retain a calcified 
cartilaginous core in the medullary region in at least 
young individuals. They both exhibit cyclical bone growth 
of lamellar to parallel-fibred bone matrices with 
undulating incremental growth marks and low to moderate 
vascularisation (lamellar-zonal bone tissue type). 
Interspecific variation comprises differences in the 
distribution of differently organised bone matrices and 
the size, orientation and number of vascularisation. The 
vascularisation pattern (abundance and orientation of the 
canals) of the pachyosteosclerotic long bones of C. 
calcagnii mostly resembles the histotype of the 
stratigraphically youngest pachypleurosaurid from Monte 
San Giorgio, Neusticosaurus edwardsii (except for the 
presence of primary osteons in the cortex of the former). 
The bone sample of C. lanzi is only osteosclerotic and 
most similar to young Nothosaurus (except for the 
irregular presence of fibrolamellar bone in the latter). 
The slightly different growth pattern already at young 
ontogenetic stages might be linked to a different mode of 
life within the restricted lagoonal basin for 
Ceresiosaurus, which supports previous studies on the 
morphological data that ascribed two different locomotion 
types. 

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