Вымершие гиганты Австралии: Род Diprotodon и его эволюция.

Extinct marsupial genus

so they assumed the same would have been true for extinct relatives, including Diprotodon. These other species are:
D. annextans was erected in 1861 by Irish palaeontologist Frederick McCoy based on some teeth and a partial mandible found near Colac, Victoria; the name may be a typo of annectens, which means linking or joining, because he characterised the species as combining traits from Diprotodon and Nototherium;
D. minorwas erected in 1862 by Thomas Huxley based on a partial palate;

Diprotodon is a marsupial in the order Diprotodontia, suborder Vombatiformes (wombats and koalas), and infraorder Vombatomorphia (wombats and allies). It is unclear how different groups of vombatiformes are related to each other because the most completely known members—living or extinct—are exceptionally derived (highly specialised forms that are quite different from their last common ancestor). New species were later added to both groups; by the 1960s, the first diprotodontoids dating to before the Pliocene were discovered, better clarifying their relationship to each other. Because of this, in 1967, American palaeontologist Ruben A. Stirton subdivided Diprotodontoidea into one family, Diprotodontidae, with four subfamilies; Diprotodontinae (containing Diprotodon among others), Nototheriinae, Zygomaturinae, and Palorchestinae. In 1977, Australian palaeontologist Michael Archer synonymised Nototheriinae with Diprotodontinae and in 1978, Archer and Australian palaeontologist Alan Bartholomai elevated Palorchestinae to family level as Palorchestidae, leaving Diprotodontoidea with families Diprotodontidae and Palorchestidae; and Diprotodontidae with subfamilies Diprotodontinae and Zygomaturinae. Below is the Diprotodontoidea family tree according to Australian palaeontologists Karen H. Black and Brian Mackness, 1999 (top), Diprotodon has been found in every Australian state, making it the most widespread Australian megafauna in the fossil record. Both diprotodontines and zygomaturines were both apparently quite diverse over the Late Oligocene to Early Miocene, roughly 23 million years ago, though the familial and subfamilial classifications of diprotodontoids from this period is debated. Compared to zygomaturines, diprotodontines were rare during the Miocene, the only identified genus being Pyramios. coinciding with the spread of open forests. Price and Australian palaeontologist Katarzyna Piper reported the earliest, indirectly dated Diprotodon fossils from the Nelson Bay Formation at Nelson Bay, New South Wales, which dates to 1.77 million to 780,000 years ago during the Early Pleistocene. These remains are 8–17% smaller than those of Late Pleistocene Diprotodon but are otherwise indistinguishable. efn|They were unsure if it was appropriate to classify the Nelson Bay material into a new species based on the size and temporal difference, so they tentatively designated them as D. ?optatum. The oldest directly dated Diprotodon fossils come from the Boney Bite site at Floraville, New South Wales; they were deposited approximately 340,000 years ago during the Middle Pleistocene based on U series dating and luminescence dating of quartz and orthoclase. Floraville is the only identified Middle Pleistocene site in tropical northern Australia. They may also have helped dissipate stresses produced by biting more efficiently across the skull. The occipital bone, the back of the skull, slopes forward at 45 degrees unlike most modern marsupials, where it is vertical. The base of the occipital is significantly thickened. The occipital condyles, a pair of bones that connect the skull with the vertebral column, are semi circular and the bottom half is narrower than the top. The inner border, which forms the foramen magnum where the spinal cord feeds through, is thin and well defined. The top margin of the foramen magnum is somewhat flattened rather than arched. The foramen expands backwards towards the inlet, especially vertically, and is more reminiscent of a short neural canal—the tube running through a vertebral centrum where the spinal cord passes through—than a foramen magnum. A sagittal crest extends across the midline of the skull from the supraoccipital—the top of the occipital bone—to the region between the eyes on the top of the head. The orbit (eye socket) is small and vertically oval shaped. The nasal bones slightly curve upwards until near their endpoint, where they begin to curve down, giving the bones a somewhat S shaped profile. Like many marsupials, most of the nasal septum is made of bone rather than cartilage. The nose would have been quite mobile. The height of the skull from the peak of the occipital bone to the end of the nasals is strikingly almost uniform; the end of the nasals is the tallest point. The zygomatic arch (cheek bone) is strong and deep as in kangaroos but unlike those of koalas and wombats, and extends all the way from the supraoccipital.

As in kangaroos and wombats, there is a gap between the jointing of the palate (roof of the mouth) and the maxilla (upper jaw) behind the last molar, which is filled by the medial pterygoid plate. This would have been the insertion for the medial pterygoid muscle that was involved in closing the jaw. Like many grazers, the masseter muscle, which is also responsible for closing the jaw, seems to have been the dominant jaw muscle. A probable large temporal muscle compared to the lateral pterygoid muscle may indicate, unlike in wombats, a limited range of side to side jaw motion means Diprotodon would have been better at crushing rather than grinding food. The insertion of the masseter is placed forwards, in front of the orbits, which could have allowed better control over the incisors. Diprotodon chewing strategy appears to align more with kangaroos than wombats: a powerful vertical crunch was followed by a transverse grinding motion. As in other marsupials, the ramus of the mandible, the portion that goes up to connect with the skull, angles inward. The condyloid process, which connects the jaw to the skull, is similar to that of a koala. The ramus is straight and extends almost vertically, thickening as it approaches the body of the mandible where the teeth are. The depth of the body of the mandible increases from the last molar to the first. The strong mandibular symphysis, which fuses the two halves of the mandible, begins at the front most end of the third molar; this would prevent either half of the mandible from moving independently of the other, unlike in kangaroos which use this ability to better control their incisors. As in kangaroos, the necks of the lophs are coated in cementum. Unlike in kangaroos, there is no connecting ridge between the lophs. The peaks of these lophs have a thick enamel coating that thins towards the base; this could wear away with use and expose the dentine layer, and beneath that osteodentine. Like the first premolar of other marsupials, the first molar of Diprotodon and wombats is the only tooth that is replaced. D. optatum premolars were highly morphologically variable even within the same individual.

Diprotodon had five cervical (neck) vertebrae. The atlas, the first cervical (C1), has a pair of deep cavities for insertion of the occipital condyles. The diaphophyses of the atlas, an upward angled projection on either the side of the vertebra, are relatively short and thick, and resemble those of wombats and koalas. The articular surface of the axis (C2), the part that joints to another vertebra, is slightly concave on the front side and flat on the back side. As in kangaroos, the axis has a low subtriangular hypophysis projecting vertically from the underside of the vertebra and a proportionally long odontoid—a projection from the axis which fits into the atlas—but the neural spine, which projects vertically the topside of the vertebra, is more forwards. The remaining cervicals lack a hypophysis. As in kangaroos, C3 and C4 have a shorter and more compressed neural spine, which is supported by a low ridge along its midline in the front and the back. The neural spine of C5 is narrower but thicker, and is supported by stronger but shorter ridges. Diprotodon probably had 13 dorsal vertebrae and 14 pairs of closely spaced ribs. Like many other mammals, the dorsals initially decrease in breadth and then expand before connecting to the lumbar vertebrae. Unusually, the front dorsals match the short proportions of the cervicals, and the articular surface is flat. At the beginning of the series, the neural spine is broad and angled forward, and is also supported by a low ridge along its midline in the front and the back. In later examples, the neural spine is angled backwards and bifurcates (splits into two). Among mammals, bifurcation of the neural spine is only seen in elephants and humans, and only in a few of the cervicals and not in the dorsals. Compared to those of wombats and kangaroos, the neural arch is proportionally taller. As in elephants, the epiphysial plates (growth plates) and the neural arch, to which the neural spine is attached, are anchylosed—very rigid in regard to the vertebral centrum—which served to support the animal's immense weight. Like most marsupials, Diprotodon likely had six lumbar vertebrae. They retain a proportionally tall neural arch but not the diapophyses, though L1 can retain a small protuberance on one side where a diapophysis would be in a dorsal vertebra; this has been documented in kangaroos and other mammals. The length of each vertebra increases along the series so the lumbar series may have bent downward. Like other marsupials, Diprotodon had two sacral vertebrae. The base of the neural spines of these two were ossified (fused) together.

The general proportions of the scapula (shoulder blade) align more closely with more basal vertebrates such as monotremes, birds, reptiles, and fish rather than marsupials and placental mammals. It is triangular and proportionally narrow but unlike most mammals with a triangular scapula, the arm attaches to top of the scapula and the subspinous fossa (the fossa, a depression below the spine of the scapula) becomes bigger towards the arm joint rather than decreasing. The glenoid cavity where the arm connects is oval shaped as in most mammals. Unlike other marsupials, the ilia, the large wings of the pelvis, are lamelliform (short and broad, with a flat surface instead of an iliac fossa). Lamelliform ilia have only been recorded in elephants, sloths, and apes, though these groups all have a much longer sacral vertebra series whereas marsupials are restricted to two sacral vertebrae. The ilia provided strong muscle attachments that were probably oriented and used much the same as those in an elephant. The sacroiliac joint where the pelvis connects to the spine is at 35 degrees in reference to the long axis of the ilium. The ischia, which form part of the hip socket, are thick and rounded tailwards but taper and diverge towards the socket, unlike those in kangaroos, where the ischia proceed almost parallel to each other. They were not connected to the vertebra. The hip socket itself is well rounded and almost hemispherical.

Unlike those of most marsupials, the humerus of Diprotodon is almost straight rather than S shaped, and the trochlea of the humerus at the elbow joint is not perforated. The ridges for muscle attachments are poorly developed, which seems to have been compensated for by the powerful forearms. Similarly, the condyles where the radius and ulna (the forearm bones) connect maintain their rounded shape and are quite similarly sized, and unusually reminiscent of the condyles between the femur and the tibia and fibula in the leg of a kangaroo. Like elephants, the femur of Diprotodon is straight and compressed anteroposteriorly (from headside to tailside). The walls of the femur are prodigiously thickened, strongly constricting the medullary cavity where the bone marrow is located. The proximal end (part closest to the hip joint) is notably long, broad, and deep. The femoral head projects up far from the greater trochanter. As in kangaroos, the greater trochanter is split into two lobes. The femoral neck is roughly the same diameter as the femoral head. Also as in kangaroos, the condyle for the fibula is excavated out but the condyle for the tibia is well rounded and hemispherical. Like those of many other marsupials, the tibia is twisted and the tibial malleolus (on the ankle) is reduced.

Diprotodon has five digits on either paw. Like other plantigrade walkers, where the paws were flat on the ground, the wrist and ankle would have been largely rigid and inflexible. The enlarged pisiform bone takes up half the jointing surface of the ulna. The fifth digit on the forepaw is the largest. The digits of the hindpaws turn inwards from the ankle at 130 degrees. The second and third metatarsals (the metatarsals connect the toes to the ankle) are significantly reduced, which may mean these digits were syndactylous (fused) like those of all modern diprotodontians. The first, fourth, and fifth digits are enlarged. The toes are each about the same length, except the fifth which is much stouter.

Diprotodon is the largest known marsupial to ever have lived. As researchers were formulating predictive body mass equations for fossil species, efforts were largely constrained to eutherian mammals rather than marsupials. In 2003, Australian palaeontologist Stephen Wroe and colleagues took a more sophisticated approach to body mass than Murray's estimate. They made a regression between the minimum circumference of the femora and humeri of 18 quadrupedal marsupials and 32 placentals against body mass, and then inputted 17 Diprotodon long bones into their predictive model. The results ranged from , for a mean of , though Wroe said reconstructing the weight of extinct creatures that far outweighed living counterparts is problematic. For comparison, an American bison they used in their study weighed and a hippo weighed Carbon isotope analysis suggests Diprotodon fed on a broad range of foods and, like kangaroos, was consuming both C3—well watered trees, shrubs, and grasses—and C4 plants—arid grasses. Carbon isotope analyses on Diprotodon excavated from the Cuddie Springs site in units SU6 (possibly 45,000 years old) and SU9 (350,000 to 570,000 years old) indicate Diprotodon adopted a somewhat more varied seasonal diet as Australia's climate dried but any change was subtle. In contrast, contemporary kangaroos and wombats underwent major dietary shifts or specialisations towards, respectively, C3 and C4 plants. The fossilised, incompletely digested gut contents of one 53,000 year old individual from Lake Callabonna show its last meal consisted of young leaves, stalks, and twigs. The molars of Diprotodon are a simple bilophodont shape. Kangaroos use their bilophodont teeth to grind tender, low fibre plants as a browser as well as grass as a grazer. Kangaroos that predominantly graze have specialised molars to resist the abrasiveness of grass but such adaptations are not exhibited in Diprotodon, which may have had a mixed diet similar to that of a browsing wallaby. It may also have chewed like wallabies, beginning with a vertical crunch before grinding transversely, as opposed to wombats, which only grind transversely. Similarly to many large ungulates (hoofed mammals), the jaws of Diprotodon were better suited for crushing rather than grinding, which would have permitted it to process vegetation in bulk. Though these are likely overestimates, This specimen became one of the most cited pieces of evidence humans and megafauna directly interacted until a 2020 re analysis by Australian palaeoanthropologist Michelle Langley identified the engraver as most likely a tiger quoll. In 2016, Australian archaeologist Giles Hamm and colleagues unearthed a partial right radius belonging to a young Diprotodon in the Warratyi rock shelter. Because it lacks carnivore damage and the rock shelter is up a sheer face Diprotodon is unlikely to have climbed, they said humans were responsible for taking the bone to the site.

[[File:Bunyip 1890 (cropped). jpg|left|thumb|Diprotodon, soon after discovery, was associated with the bunyip (above drawn by J. Mcfarlane, 1890). If Pleistocene megafauna are the basis of some aboriginal mythology, it is unclear if the stories were based on the creatures when they were alive or their fossils being discovered long after their extinction.

Aboriginal Australians decorated caves with paintings and drawings of several creatures but the identities of the subjects are often unclear. In 1907, Australian anthropologist Herbert Basedow found footprint petroglyphs in Yunta Springs and Wilkindinna, South Australia, which he believed were those of Diprotodon. In 1988, Australian historian Percy Trezise presented what he thought was a Quinkan depiction of Diprotodon to the First Congress of the Australian Rock Art Research Association. Both of these claims have their faults because the depictions bear several features that are inconsistent with what is known about Diprotodon. Unlike the more naturalistic artwork of Early European modern humans, which are more easily identifiable as various animals, aboriginal artwork is much more stylistic and is mostly uninterpretable by an outsider. The subjects of aboriginal paintings can be mythological beings from the Dreaming rather than a corporeal subject.