Floridaceras
Floridaceras is a now extinct species of rhinoceros and lived in the Lower and Middle Miocene epoch, 20-15 million years ago, mainly in North America but also in present-day Panama proven. It belongs to the group of Aceratheriinae and was of a size that is comparable with today's black rhino, one of America's largest rhino representative. Characteristic of the genus were extremely long and slender legs, and the missing horn.
Features
Floridaceras was one of the largest rhino representatives in North America, reaching a weight of about 1 to 2 t about the size of today's black rhino ( Diceros bicornis). Characteristic were the long legs that had not yet experienced any cuts like his relatives Aceratherium. Also an original feature is the four-engine forefoot. The hind feet ended like all rhinos into three beams.
The skull is preserved only fragmented, especially in the area of the rostrum. The occiput was formed narrow and short. Remarkably, Floridaceras possessed a distinct sagittal crest on the parietals, which is typical for some very early rhinos, but does not occur in today. The nose was rather weakly developed and fell forward slightly. On the surface there is no roughened surfaces, so to assume that is that the rhino species had not formed horns were. The nasal interior extended to the third premolar and was significantly less pronounced than in later Aceratheriinen.
The mandible reached a length of 55 cm, the body of the mandible had a strong construction and was up to 8.9 cm high. The dentition was reduced slightly and had no canine on more, but the exact number of front teeth is not known. However, the lower jaw had been found to have an incisor, the second ( I2), which was pointed- conical in shape. At the rear dentition, which consisted of four premolars and three molars each pine bough, was a large, up to 10 cm long diastema. The molars showed generally low ( brachyodonte ) dental crowns. The first two premolars were small and hardly molarisiert, the rear two, however, were similar to the molars significantly. These were large, and the last almost 6 inches long.
The postcranial skeleton is only partially known, the spine is largely not known. One of the few known thoracic vertebrae had an unusually long, up to 26 cm measured spinous process. Characteristic were the long limbs, the humerus reached 44 cm in length, the femur, however, 58 cm. The lower limbs, however, were significantly shorter and reached 36 cm at 33 cm of the ulna and the tibia. The forefoot is not fully known, but had a long and functional fifth beam was a total vierstrhlig ( tetradactyl ) constructed ( metacarpal II to V), also a primordial feature. The rhino had hind typical three beams ( metatarsus II to IV), the third metatarsal was up to 16.8 cm long.
Fossil finds
The majority of the finds are known from North America, mainly from the U.S. state of Florida and is taken mainly by a quarry on the grounds of the Thomas Farm in Gilchrist County. These findings comprise about 60 fossil remains of the skull and skeleton of the body; they are now in the Florida Museum of Natural History. Another partial skeleton was discovered in Dawes County, Nebraska, while only some individual finds known from Oregon. With some of the lower jaw fragments and long bone remains the rhino genus is also represented in the Gaillard Cut Local Fauna in Panama. All finds belong to the Lower and Middle Miocene. Overall Floridaceras showed indeed widespread, but was due to the rather scanty remains a well rare faunal element of the time.
Paleobiology
The niederkronigen molars have a preference for soft plant foods accept ( browsing ). Isotope studies on the teeth confirmed this assumption and show that possibly shrubs or small trees were used as food resources. Moreover, since hardly variations are detected in the isotopic values of oxygen and carbon, the researchers expect a little over the year fluctuating food supply. The climate is therefore reconstructed as tropical and warm with only slight seasonal temperature and precipitation changes. Further investigations concerned the Paläohabitat in the southernmost area of distribution. Here are some experts expected a formation of an archipelago in the Middle Miocene in southern Central America before North and South America were ultimately connected via a land bridge in the Pliocene. Based on the mammalian fauna of this can not confirm since most large animal species, so also Floridaceras, had a similar body size as their North American counterparts and a Inselverzwergung obviously has not occurred here.
System
Uintaceras
Teletaceras
Penetrigonias
Trigonias
Amphicaenopus
Skinneroceras
Floridaceras
Aphelops
Galushaceras
Peraceras
Floridaceras is a genus of the family of rhinos. Within the rhino it be put to subfamily Aceratheriinae, phylogenetically older representatives, which were characterized by the lack of horn formations on the nose or skull. The tetradactyle forefoot and the archaic structure of the molars refer Floridaceras in a fairly early position within this subfamily, nearest allied forms are Aceratherium from Europe or the also very large Aphelops from North America. With these it belongs together in the tribe of Aceratheriini.
The genus is monotypic Floridaceras whitei with the only kind Floridaceras. The genus name refers to the Fund Florida region, while the Greek words α (a " not " ) and κέρας ( keras " horn " ) highlight the absence of the horn. The species name whitei, the American scientist Theodore E. White is honored, who collected numerous fossil finds on the site of the Thomas Farm in Florida and so contributed to the discovery of Floridaceras, which he presented in 1942 an assessment of the geological age position of the finds. Was first described the genus in 1964 by Horace Elmer Wood based on information collected by White finds. As holotype is considered a damaged skull with preserved posterior molars ( copy number MCZ 4046 ).