STL Science Center

STL Science Center

23 March 2016

Types of Fossils

The type species, Chalicotherium goldfussi, is known from the Miocene and Pliocene of Europe. Factoring in the Late Oligocene fossils that are attributed to other species, Chalicotherium can be said to have existed for a rather long time, as far as giant mammals are concerned. This is said considering that the "typical" species exists for somewhere between 5 - 10 million years given accepted extinction rates but there are certainly outliers on both ends of that spectrum. The total time in the fossil record for which we know of Chalicotherium fossils totals approximately 24 million years (28.4 - 3.6 mya); clearly this genus could potentially represent an outlier from the accepted generalization. The type species is from the Upper Miocene of Germany (around 12 - 5.4 mya) and is estimated to be approximately 1500 kg and 2.6 m tall at the shoulder. The other two species are similarly sized and were initially known from around a contemporaneous geological era. Chalicotherium salinum was originally known from the Lower Pliocene (5.3 - 3.6 mya) in Pakistan and India also making it the youngest of the Chalicotherium species. All of these species are extremely large and were highly adapted for herbivory; gigantic herbivores is a commonly reoccurring theme in the history of life. Some of these adaptations include the horse-like head with a muscular set of lips capable of grasping vegetation and taking it into the mouth. The apparent loss of the incisors and canines throughout ontogeny has been linked to this cropping action in that the muscular lips are hypothesized to have worked against the resulting gumline to successfully crop vegetation more efficiently than the canines and incisors. The remaining teeth were molars that were squared in appearance. These teeth possessed low crowns suited for grinding vegetation passed back by the tongue from the muscular lips and gumlines.

While doing all of this processing and cropping of leaves, Chalicotherium did an extensive amount of lounging about and loitering. That loitering is preserved in callouses on the ischium where all of the weight of the mammal was situated as it sat under trees eating and processing. We can kind of think of Chalicotherium in terms of modern pandas and sloths.
Museu Geològic del Seminari de Barcelona

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