Field of Science

Cartoons and Earth Sciences: Mammals nibbling off dinosaurs

"Beware to the teachings of those, whose ideas are not confirmed by experience."
Leonardo da Vinci (1452-1519)

Caricatures and cartoons can bring science and scientific discussion to the attention of a broader public, they also can transport messages, direct critic to a topic or unintentionally predict future discoveries...

Fig.1. A cartoon by Dr. Robert Bakker (1986) lampooning the assumption that dinosaurs were cold-blooded animals and during cold periods were easy prey for mammals.
"Mesozoic nightmare: being a cold-blooded dinosaur during the rainy season. If big dinosaurs really were mass homeotherms, then the rainy season would have sapped their body heat and left them torpid and vulnerable to the warm-blooded mammals."

This cartoon, drawn by the palaeontologist Dr. Robert Bakker, is criticising the image of dinosaurs predominant some decades ago. Dinosaurs, especially the giant sauropods, were generally assumed as cold-blooded , very lazy animals. Mammals were depicted as furry, insignificant and even superfluous animals during the Mesozoic, and considering the media coverage in some quarters it's seems still so...

But let's consider, not to seriously, the relationships of gnawing mammals and dinosaurs.
There are more than 100 theories to explain the extinction of the vast majority of dinosaurs. Between the more improbable suggested hypothesis we find that mammals feed on dinosaur eggs (which does not explain the extinction of marine reptiles, pterosaurs, ammonites and other molluscs etc...) and caused an extinction by eliminating the unborn generations.
After this idea, the mammals, after million of years of coexistence, decided that time was come for revenge, and devoured as many eggs as they possible can to drive dinosaurs to a slow, but inevitable extinction.

The hypothesis that mammals fed on (some) dinosaur eggs is plausible, but so far we lack the fossil evidence, unlike the evidence that mammals preyed (small) dinosaurs and, after the release of a new research, gnaw on dinosaur bones. In 2005 the giant Mesozoic mammal Repenomamus robustus , a mammal up to 1 meter long, was described, and found with an accumulation of little dinosaur bones within his chest.

Now a research of bones excavated from Canadian cretaceous sediments revealed little gnaw-imprints on bones of dinosaurs, aquatic reptiles and marsupials.

Nicholas Longrich of the Yale University and Michael J. Ryan of the Cleveland Museum of Natural History interpret these bite marks as gnawing on bones by probable representative of the Multituberculata, to assimilate the mineral components of the bones.

Fig.2. The marks identified as probable signs of a mammals gnawing the bones, from MUZZIN 2010.

And even if I am pro-mammal, to argue after these findings that dinosaurs were eaten by mammals is still very hypothetical...


BAKKER, R.T. (1986): the Dinosaur Heresies - New Theories Unlocking the Mystey of the Dinosaurs and Their Extinction. William Morrow and Co., New York: 481
MUZZIN, S.T. (2010): Dinosaur-chewing mammals leave behind oldest known tooth marks. Online 16.06.2010, visited 17.06.2010

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