A simulated bird gastric mill and its implications for fossil gastrolith authenticity

Wings, Oliver

doi:10.5194/fr-12-91-2009

Cited by 2 publications

(3 citation statements)

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“…Occasional finds of polished pebbles with sauropod skeletons (e.g. Janensch, 1929 b ; Bird, 1985; Christiansen, 1996) were taken as evidence for such a gastric mill, but comparative and experimental work (Wings & Sander, 2007; Wings, 2007, 2009) on ostriches and other herbivorous birds indicates that these pebbles are not the remains of an avian‐style gastric mill, leaving it uncertain whether and how sauropods reduced particle size.…”

Section: Bauplan and Biology Of Sauropod Dinosaursmentioning

confidence: 99%

Biology of the sauropod dinosaurs: the evolution of gigantism

et al. 2010

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The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism.We review the biology of sauropod dinosaurs in detail and posit that sauropod gigantism was made possible by a specific combination of plesiomorphic characters (phylogenetic heritage) and evolutionary innovations at different levels which triggered a remarkable evolutionary cascade. Of these key innovations, the most important probably was the very long neck, the most conspicuous feature of the sauropod bauplan. Compared to other herbivores, the long neck allowed more efficient food uptake than in other large herbivores by covering a much larger feeding envelope and making food accessible that was out of the reach of other herbivores. Sauropods thus must have been able to take up more energy from their environment than other herbivores.The long neck, in turn, could only evolve because of the small head and the extensive pneumatization of the sauropod axial skeleton, lightening the neck. The small head was possible because food was ingested without mastication. Both mastication and a gastric mill would have limited food uptake rate. Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates.The extensive pneumatization of the axial skeleton resulted from the evolution of an avian-style respiratory system, presumably at the base of Saurischia. An avian-style respiratory system would also have lowered the cost of breathing, reduced specific gravity, and may have been important in removing excess body heat. Another crucial innovation inherited from basal dinosaurs was a high BMR. This is required for fueling the high growth rate necessary for a multi-tonne animal to survive to reproductive maturity.The retention of the plesiomorphic oviparous mode of reproduction appears to have been critical as well, allowing much faster population recovery than in megaherbivore mammals. Sauropods produced numerous but small offspring each season while land mammals show a negative correlation of reproductive output to body size. This permitted lower population densities in sauropods than in megaherbivore mammals but larger individuals.Our work on sauropod dinosaurs thus informs us about evolutionary limits to body size in other groups of herbivorous terrestrial tetrapo...

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Section: Bauplan and Biology Of Sauropod Dinosaursmentioning

confidence: 99%

Biology of the sauropod dinosaurs: the evolution of gigantism

et al. 2010

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“…Wings (2004, 2007) undertook the first extensive study of gastroliths in extinct vertebrates and concluded that high polish does not characterize gastroliths and that without a plausible skeletal association (i.e., mass of stones in the abdominal cavity), no sand/gravel can be verified as gastroliths. Actualistic studies also convinced Wings & Sander (2007, p. 637) that “natural stones taken up by a bird will not develop any polish in its gastric mill.” Indeed, Wings (2009) simulated an avian gastric mill, and it did not polish stones.…”

Section: Introductionmentioning

confidence: 99%

“…They range from calling any polished stone at an archeological site a gastrolith (e.g., Bottema, 1975) to more nuanced treatments at hunting camps where the harvesting of birds finds other evidence beyond their supposed gastroliths, which are not necessarily polished (e.g., Brooks et al, 2012). Yet, despite the work of Wings (2004, 2007, 2009) and others back to Bryan (1931), some archaeologists (e.g., Bomberger, 2020; Moore et al, 2010; Watson & Kucera, 2014), including a book on archaeological techniques (Reitz & Shackley, 2012), and some paleontologists (e.g., Malone et al, 2021), continue to identify polished stones without a skeletal association as gastroliths (but see Schroeder & Greer, 2019, for an archaeological analysis that embodies the results of Wings).…”

Section: Introductionmentioning

confidence: 99%

Gastroliths in archaeology: A note of caution

Lucas

Hunt²

2021

Intl J of Osteoarchaeology

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Polished stones at archaeological sites are often identified as avian gastroliths, even though they lack a skeletal association. Such identification is based on the misconception that high polish characterizes gastroliths, an old idea refuted by diverse research. Thus, polished stones at archaeological sites are not necessarily gastroliths, and more rigor is urged in the identification and interpretation of such stones.

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A simulated bird gastric mill and its implications for fossil gastrolith authenticity

Cited by 2 publications

References 5 publications

Biology of the sauropod dinosaurs: the evolution of gigantism

Biology of the sauropod dinosaurs: the evolution of gigantism

Gastroliths in archaeology: A note of caution

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