STL Science Center

STL Science Center

19 January 2019

Animals Not Often Known

This week I decided that we really ought to get a little bit of knowledge into an odd group of animals that we have never looked at before. We have explored a lot of marine animals including fish, mammals, and reptiles. There is a set of aquatic mammals that we have not yet explored. This group of marine mammals is known, largely, today as the "sea cows." One of the genera that best represents the group is a globally known genus called Metaxytherium. The genus Metaxytherium consists of 8 species (M. albifontanum Vélez-Juarbe and Domning, 2014; M. arctodites Aranda-Manteca et al., 1994; M. crataegense Simpson, 1932; M. floridanum Hay, 1922; M. krahuletzi Depéret, 1895; M. medium Demarest, 1822 (type species); M. serresii Gervais, 1847 and M. subapenninum Bruno, 1839) represented from the Miocene into the Pleistocene. Dugongs, the family (Dugongidae) of organisms to which Metaxytherium belongs, is a capable of living in both marine (salt) and freshwater systems and Metaxytherium was not an exception with taxa being discovered in both coastal and inland fossil deposits. Metaxytherium looks, skeletally, very similar to extant manatees and dugongs; you can see the skeleton of M. floridanum below.
Photo by Ryan Somma

05 January 2019

Fossils and Parrots

When one searches fossil parrot two things appear. One is a report of a partial tarsometatarsus (a bone in the foot) from Siberia that was dated to 16-18 MYA. This is interesting, but it is a very small part of a parrot. A proto-parrot from Wyoming also appears regularly in the search list. This animal, shown below, does not have the familiar head shape of parrots, but does possess other features of parrots and is a whole bird; though it is in the typical bird state of a fossil which is to say that it is nearly pressed entirely flat. This fossil comes from the Fossil Butte Member of Green River Formation and has exceptional preservation, despite the crushed nature of the fossil. If you were to look closely at the neck you can see tracheal rings, the cartilage circles that keep the trachea ("windpipe") open so animals can breathe. Other fossil parrots are known to science, but many of them are associated with much older discoveries, so the papers describing these finds are not high on the search returns. These include parrots found in the Miocene of Nebraska (Wetmore 1926), New Zealand and Australia (latest paper: Worthy et al. 2011), and the Czech Republic (Mlíkovský 1998). There are other papers describing fossil parrots as well, but some describe the same finds mentioned above or are reviews of what we know about the parrot fossil record.
Cyrilavis colburnorum photo by Ian N. Cost