Потребителски вход

Запомни ме | Регистрация
16.12.2015 19:11 - Encyclopedia Largest Prehistoric Animals Vol.1 Vertebrates part1 Mammals ch.5 Proboscideans-Еarlier elephants-huge from the beginning of his way of life
Автор: valentint Категория: Забавление   
Прочетен: 5824 Коментари: 0 Гласове:

Последна промяна: 15.06.2020 02:29

 Elephants,mammoths,mastodons and kin (Proboscidea)


The elephants and their extinct relatives,including mammoths, mastodons, gomphotheres, deinotheres, barytheres,and others, make up the Proboscidea.
The two living species of elephants (Elephantidae), with restricted distributions in Africa and southeast Asia, are all that remains of a once much wider radiation. Ten extinct families are recognized by McKenna and Bell (1997).
Beginning in the mid Miocene, most members of this order were very large animals. The largest land mammal today is the African elephant weighing up to 10.4 tonnes with a shoulder height of up to 4 metres (13.1 ft).The largest land mammal of all time may have also been a proboscidean: Palaeoloxodon namadicus, which may have weighed up to 22 t (24.3 short tons) with a shoulder height of up to 5.2 metres (17.1 ft), surpassing several sauropod dinosaurs (in height).
The name Proboscidea, of course,derives from the long, flexible, trunk, or proboscis, of derivedforms, but many early proboscideans lacked a trunk.
Evolution of the trunk has been explained as one solution to the problem of feeding and drinking in animals of increasing body size.As body mass and skull size increased over time, it became biomechanically advantageous to shorten the neck and skull, as well as to straighten the limbs,thereby further elevating the head. In such circumstances,a trunk provides an efficient and safe way to procure food and water.
order apparently originated in Africa in the Paleocene or possibly earlier, although potential primitive early members (anthracobunids) are also known from the Eocene of southeast Asia. In the Miocene, diverse proboscideans dispersed throughout the northern continents and eventually reached South America as well.
The very first members of the elephant order arose in Africa, and remained there exclusively during the Paleocene and Eocene epochs. The oldest known example is from fragmentary remains found in 1996 from the Paleocene of Morocco. These ancient proboscids, such as Numidotherium, are poorly preserved, but resemble the better preserved Moeritherium which arose later in the upper Eocene in Egypt.

1. Prodeinotherium 2. Phosphatherium 3. Palaeomastodon 4. Deinotherium 5. Moeritherium
Charles William Andrews described Moeritherium and suggested that it was an amphibious creature that lived in swamps or shorelines. The skeleton is of a small pig-like animal with short limbs and a barrel-like body. There is no evidence of a trunk, though some authors and illustrators depict Moeritherium with a prehensile snout like a tapir.
The dentition of modern elephants differs widely from the ancient Moeritherium, and presumably other ancient proboscids as well. Moeritherium has multiple pairs of molars and premolars, unlike modern elephants. While the second incisors of Moeritherium are greatly enlarged, it does not possess tusks and it retains canines on the upper jaw, separated from the cheek teeth by a gap known as a diastema.
Despite the resemblance of Moeritherium to the earliest proboscideans, they are not thought to be ancestral to modern elephants, rather a relict clade of the order that died out and left no descendants. Moeritherium does share some characteristics with the aquatic desmostylians, which evolved later in the Oligocene epoch. The precise relationship between the desmostylians and the proboscids is unclear.

Suborder † Plesielephantiformes

                    Family †Barytheriidae

                                              Genus † Bariterii Barytherium
Barytherium (meaning heavy beast) is a genus of an extinct family (Barytheriidae) of primitive proboscidean that lived during the late Eocene and early Oligocene in North Africa. The Barytheriidae were the first large size proboscideans to appear in the fossil records and were characterized by a strong sexual dimorphism. It was about 1.8-2 m tall at the shoulder and weighed about 2 tonnes.
The only known species within this family is Barytherium grave, found at the beginning of the 20th century in the Fayum, Egypt. More complete specimens have been found since then, at Dor el Talha Libya and most recently at Aidum area in Oman. In some respects, these animals would have looked similar to a modern Asian Elephant, but with a more slender build.The most visible difference, however, would have been the tusks. Barytherium had eight very short tusks, four each in the upper and lower jaws, which resembled those of a modern hippopotamus more than those of an elephant. The upper pairs were vertical, while the lower pairs projected forwards from the mouth horizontally. Together, these would have created a shearing action for cropping plants.
Barytherium fossils were discovered in 2011 in the Aidum area in Dhofar by Oman"s Ministry of Heritage and Culture and brought to Sultan Qaboos University (SQU) for identification. The team included Professor Sobhi Nasir and Dr. Abdulrahman al Harthy from SQU and Dr. Erick Seifert from SUNY Stony Brook, New York. The scientists named the new finding Barytherium omans.

Family † Deinotheriidae

                Subfamily † Chilgatheriinae
                                     Genus † Chilgatherium

Chilgatherium ("Chilga Beast" after the locality in which it was found) is the earliest and most primitive representative of the family Deinotheriidae. It is known from late Oligocene (27 to 28 million years old)-aged fossil teeth found in the Ethiopian district of Chilga. So far, only a number of molarteeth have been found, but these are distinct enough that this animal can be identified with confidence. The teeth differ from those of Prodeinotherium, Deinotherium, and the various barytheres in various details, enough to show that this is a distinct type of animal, and has been placed in its own subfamily. Compared to later deinotheres, Chilgatherium was quite small, about 2 m (6.6 ft) tall at the shoulder and weighed about 1.5 t (1.7 short tons). It is not known if it shared the distinctive downward-curving tusks on the lower jaw that the later deinotheres had. Chilgatherium disappears prior to the Early
Miocene, where Prodeinotherium occurs instead.

Subfamily †Deinotheriinae
                           Genus †Prodeinotherium
Prodeinotherium is an extinct representative of the family Deinotheriidae that lived in Africa, Europe, and Asia in the early and middle Miocene. Prodeinotherium was first named in 1930, meaning "before terrible beast", but soon after the only species in it, P. hungaricum, was reassigned to Deinotherium. During the 1970s however, the two genera were once again separated, with Prodeinotherium diagnosed to include Deinotherium bavaricum (=P. hungaricum), Deinotherium hobleyi, and Deinotherium pentapotamiae, which were separated based on geographic location. The three species are from Europe, Africa, and Asia respectively. However, because of usage of few characters to separate them, there may have been only one species, P. bavaricum, or many more species, including P. cuvieri, P. orlovii, and P. sinense.

All deinotheres were large animals that evolved to be even larger, and many features are shared throughout the group. Prodeinotherium and Deinotherium both had large downcurved tusks on the lower jaw, but none on the upper jaw. They may have had a tapir-like snout, muscular but not as long as an elephant"s trunk. This could have been used to grasp food while the tusks moved branches out of the way. Prodeinotherium was slightly smaller than Deinotherium, yet much larger than more primitive proboscideans. All Prodeinotherium species were similar in size, ranging from 2.5 to 2.8 m (8.2 to 9.2 ft) tall and weighing about 3.1 to 4.3 t (490 to 680 st).
Prodeinotherium was the size of the present Asian elephant, about 3–4 metres (9.8–13.1 ft) at the shoulders, but differing from elephants by lacking upper tusks and instead possessing downward-facing lower tusks.In appearance and many characters it was like Deinotherium, but differed in being of smaller size, having shorter forelimbs, and also in various details in the shape and form of the teeth.An potentially adult female specimen of P. bavaricum is estimated to be 2.47 metres (8.1 ft) tall and weight 3.1 tonnes (3.1 long tons; 3.4 short tons), while an adult male measured 2.78 metres (9.1 ft) tall and was about 4.3 tonnes (4.2 long tons; 4.7 short tons). The earliest species P. hobleyi was estimated at similar 2.7 metres (8.9 ft) tall and 4.0 tonnes (3.9 long tons; 4.4 short tons).Prodeinotherium hobleyi was larger and more specialised than its Oligocene predecessor Chilgatherium. It flourished for several millions of years, before being replaced in the middle Miocene by the much larger Deinotherium.

Genus † Deinotherium

From left to right : Deinotherium Thraceiensis, Deinotherium Giganteum, Deinotherium Proavum, Deinotherium Bozasi, Deinotherium Indicum, Prodeinotherium Bavaricum and Chilgatherium Harrisi

Deinotherium ("terrible beast" derived from the Ancient Greek deinos meaning "terrible" and therion meaning "beast") was a large prehistoric relative of modern-day elephants that appeared in the Middle Miocene and survived until the Early Pleistocene. During that time it changed very little. In life, it probably resembled modern elephants, except that its trunk was shorter, and it had downward curving tusks attached to the lower jaw.
Deinotherium is the type genus of the family Deinotheriidae, which evolved from the smaller, early Miocene Prodeinotherium. These proboscideans represent a totally distinct line of evolutionary descent to that of other elephants, one that probably diverged very early in the history of the group as a whole. The large group to which elephants belong formerly contained several other related groups: besides the deinotheres, there were the gomphotheres (some of which had shovel-like lower front teeth), and the mastodons. Only elephants survive today.
Deinotherium was a large proboscidean. Two adults of D. giganteum are around 3.63–4 metres (11.9–13.1 ft) tall and weight 8.8–12 tonnes (8.7–11.8 long tons; 9.7–13.2 short tons). This is similar to adult males of P. proavum, one of which weighted 10.3 tonnes (10.1 long tons; 11.4 short tons) and was 3.59 metres (11.8 ft) tall. However, both these species are smaller than a 45-year-old male of D. "thraceiensis", at 4.01 metres (13.2 ft) tall and 13.2 tonnes (13.0 long tons; 14.6 short tons) in weight.
Permanent tooth formula of D. giganteus is 0-0-2-3/1-0-2-3 (deciduous 0-0-3/1-0-3), with vertical cheek tooth replacement. Two sets of bilophodont and trilophodont teeth. Molars and rear premolars tapiroid, vertical shearing teeth, and show that deinotheres became an independent evolutionary branch very early on; other premolars used for crushing. The cranium is short, low, and flattened on the top (in contrast to more advanced proboscids, which have a higher and more domed forehead; the implication may be that deinotheres were less intelligent than other proboscids), with very large, elevated occipital condyles. The nasal opening is retracted and large, indicating a large trunk. The rostrum is long and the rostral fossa broad. Mandibular symphyses (the lower jaw-bone) is very long and curved downward, which, with the backward curved tusks, is a distinguishing feature of the group; it possessed no upper tusks.
Deinotherium is distinguished from its predecessor Prodeinotherium by its much greater size, greater crown dimensions, and reduced development of posterior cingula ornamentation in the second and third molar.
The way Deinotherium used its curious tusks has been much debated. It may have rooted in soil for underground plant parts like roots and tubers, pulled down branches to snap them and reach leaves, or stripped soft bark from tree trunks. Deinotherium fossils have been uncovered at several of the African sites where remains of prehistoric hominid relatives of modern humans have also been found.Deinotherium"s range covered parts of Asia, Africa, and Europe. Adrienne Mayor, in The First Fossil Hunters: Paleontology In Greek and Roman Times, has suggested that deinothere fossils found in Greece helped generate myths of archaic giant beings. A tooth of a deinothere found on the island of Crete, in shallow marine sediments of the Miocene suggests that Crete was closer or connected to the mainland during the
Messinian Salinity Crisis.

Largest Deinotherium was D. gigantissimum Stefanescu 1892( synonym D. proavum Eichwald, 1835), considered by some researchers as a major species, replacing the Pliocene D. giganteum.
As a rule, its members include large size and having a rather late age deinotherium (dating mainly in the early and middle Pliocene, but sometimes late Miocene, Serravalle - rustsiny) from a number of localities of European and Asian countries (Spain, Bulgaria, Greece, Macedonia Turkey, Romania, Moldova, Ukraine, southern Russia, and perhaps Iran, Iraq, Afghanistan, and others.).The dimensions of one of the largest skeletons of this species found in the Pliocene sediments of Moldova are as follows: length - 6 m, height - 4.5 m, the total length of the tusks - 1.5 m , the blade length - 1.2 m , the length of the femur - 1.5 m . There are fragmentary remains and larger individuals , estimated the height of which reaches about 5 m .
According to some authors, in addition to large, there are other morphological features inherent D. gigantissimum. Thus, attention is drawn to the existence of highly developed mandibular angle, outstanding outside the ventral border of the horizontal branch of the mandible, which is not observed in D. giganteum. In addition, the presence of certain specified characteristics in the structure of the skull. Yet today, many researchers are of the view according to which the mentioned features is not enough to highlight the independent type, and they may well be explained by sexual dimorphism and age.

Special mention also deserves deinotherium Thracian (D. thraceiensis Kovachev et Nikolov, 2006) -
appearance, recently described by an almost complete skeleton of the Late Miocene (meotis) deposits near the village of Ezerovo in Bulgaria. This skeleton was discovered in 1965 and in the mounted state has a very impressive size, reaching 4.65 meters at the shoulder and 6.80 m in length. This finding has a number of specific features that distinguish it from D. giganteum: the body is relatively long, and the skull - high and shortened, with a high forehead and a relatively short nasal bones, the lower jaw has a very prominent corner and is very large tusks.
The occipital pad is angled 80 ° relative to the forehead and 70 ° relative to the longitudinal line of teeth occipitotemporal very small wings.Large eye sockets . Premaxillaries expressed are folded down . On the skull did not show any signs of rugozistosti , on the contrary, it has a rounded , smooth shape . By D. thraceiensis have been ranked , and some of the finds from other localities of the south of Europe.


Suborder Elephantiformes
                    Family † Palaeomastodontidaе
Genus † Palaeomastodon
Palaeomastodon an extinct genus of Proboscidea. Palaeomastodon fossils have been found in Africa, lived some 36-35 million years ago. They are believed to be the ancestors of elephants or mastodons.
Palaeomastodon had
tusks, both upper and lower, and it had a trunk. It was about 2.2 meters tall at the shoulder and weighed about 2.5 tonnes. The lower tusks were flat rather than pointed cones, and were probably used to scoop plants from swampy water.


Family †Phiomiida
                   Genus † Phiomia
Phiomia is an extinct genus of basal proboscid that lived in what is now Northern Africa during the Late Eocene to Early Oligocene some 36-30 million years ago. "Phiomia serridens" means "saw-toothed animal of Faiyum".
Phiomia was around 2.5 metres (8.2 ft) high, and vaguely resembled a modern elephant, although, based on the shape of its nasal bones, it had only a very short trunk. It had short tusks on the upper jaw and also short shovel-like tusks on the lower jaw that were most likely used for gathering food. These were similar to those of the Miocene Platybelodon,Archaeobelodon and Amebelodon, but considerably smaller. The tusks in the upper jaw may have been used in defence or scraping bark off trees. 






Няма коментари

За този блог
Автор: valentint
Категория: Политика
Прочетен: 1068702
Постинги: 250
Коментари: 22
Гласове: 23
«  Юни, 2021