Deinotheriidae
Skeletal reconstruction of Deinotherium
The Deinotheriidae ( Deinotherien, also Dinotherien or " elephant tusks " ) was a very early, successful branch of fossil Proboscidea ( Proboscidea ), which also include the extant elephants. They lived from the Oligocene to early Pleistocene in much of the Old World. The name comes from the Greek words δεινός ( deinos, horror ) and θηρίον ( THERION, animal ) together while dino is the Latinized version of deinos. The Deinotherien are two genera assigned Chilgatherium and Deinotherium, a possible third, but sometimes controversial genus is Prodeinotherium.
Features
The Deinotherien had a today's elephants comparable hulking physique with columnar legs and a skull, which had already partially air-filled bones to reduce body mass. The earliest representatives were with a shoulder height of less than 2 m significantly smaller than the later ones, which could measure partly of 4 m and has been calculated that showed up to 14 t weight. Compared to today's elephants the skull was still well flat. The most striking difference to most other proboscidean was the expression of the tusks in the lower jaw only that there had a gereichte down position so that the pointed ends reported sometimes backwards. Made the tusks from the respective first incisors of the lower jaw were. The shape of the tusks of the lower jaw also had a prominent, downward-pointing pubic symphysis. A characteristic feature was the construction of the back teeth, all teeth were in the same function, which in turn is a significant difference to the modern proboscidean with only one functional tooth each half of the jaw. The molars had high strips of enamel on the Kauoberflächen, the maximum number of these was three ( trilophodont ).
Fossil finds
Fossil remains of Deinotherien are relatively common. The most primitive representatives, Chilgatherium is but so far only detected by the reference Chilga in Ethiopia, the fossil material comprises only a few teeth. The finds are assigned to the Oligocene and date on an age from 29 to 27 million years. Deinotherium other hand, is known from numerous sites in the Old World. Reference should be made here only to the two most complete skeletons from Eserowo near Plovdiv (Bulgaria) and Manzati (Romania). The findings largely belong to the Miocene, the youngest date from the early Pleistocene and are of African origin. Unlike many other and simultaneously occurring Rüsseltier groups, representatives of Deinotherien have never reached the Americas.
System
Primitive Proboscidea
Phosphatheriidae
Moeritheriidae
Numidotheriidae
Barytheriidae
Deinotheriidae
Younger proboscids
The Deinotheriidae constitute a family within the order of Proboscidea ( Proboscidea ) dar. The origin of Deinotherien is in Africa, where they differentiated, as this continent was at a time not connected by land bridges to other continents. The peculiarities of the teeth and teeth structure of this animal with a trunk group led occasionally to believe they would be more closely related to manatees than the proboscis animals. This view is rejected but mostly with reference to convergent evolution in not directly related animals.
The early elimination in the tusker pedigree already in the Oligocene around 30 million years ago shows especially the vertical change of teeth, a feature that represents the Deinotheriidae in the earliest phase of Radiation mammoths. Within this early proboscids a membership of Deinotherien to Plesielephantiformes as most primitive animal with a trunk group with only two enamel ridges on the two front molars ( bilophodont ) or the more modern Elephantiformes with three or four enamel folds ( tri-or tetralophodont ) is unclear. Chilgatherium had on all three molars in each case three enamel strips, while the more modern Deinotherium ( and Prodeinotherium ) this was only on the front and the second was bilophodont. Because of this complex gear structure is not known, from which the previous form of the Deinotherien emerged. The phylogenetically older Moeritherium and Barytherium from North Africa had a significantly more extensive set of teeth with anterior molars, formed from two enamel strips. Palaeomastodon, which is also formed in North Africa about 34 million years ago, had the first two molars three, but incompletely formed strips on. Perhaps both the Deinotherien and Palaeomastodon descended from an even older ancestor with trilophodonten molars and the Deinotherien reduced over time their third strip on the two rear teeth.
The family name Charles Lucien Jules Laurent Deinotheriidae coined Bonaparte (1803-1857) for the first time in 1845 within the Deinotherien two genera are distinguished which are each assigned to a separate subfamily, the distinction between the subfamilies is based on the different structure of the molars.:
- Deinotheriidae Bonaparte 1845 Chilgatheriinae Sanders, Kappelman & Rasmussen 2004 Chilgatherium Sanders, Kappelman & Rasmussen 2004
- Deinotherium ( Prodeinotherium ) Kaup 1829
Whether the forms of J. Éhik 1930, introduced on the basis of Hungarian fossils Prodeinotherium (of Éhik called Prodinotherium ) was a separate genus within the Deinotheriinae, is controversial, and the few divisive features in addition to significant differences in body size in the expression of the third premolar, the form to find the skull and the structure of the occipital bone. This is to some researchers but not enough to warrant two separate genera. The phylogeny of Deinotherien is generally characterized by a steady increase in body size, which lasted until the end and so often led to different taxonomic designations.