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18.12.2015 16:30 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part1 Mammals ch.13 Elks and Mooses
Автор: valentint Категория: Забавление   
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Cervidae
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The Cervidae first appear as fossils in the early Miocene of Asia, where they expanded into a wide variety of niches (and were thus able to dominate over the bovids which arrived later). During the Miocene, members of this family migrated to North America. After expanding in the Nearctic region, deer crossed to South America during the Pleistocene, when the Panama land bridge formed.
Deer are believed to have evolved from antlerless, tusked ancestors that resembled modern duikers and diminutive deer in the early Eocene, and gradually developed into the first antlered cervoids (the superfamily of cervids and related extinct families) in the Miocene. Eventually, with the development of antlers, the tusks as well as the upper incisors disappeared. Thus evolution of deer took nearly 30 million years. Biologist Valerius Geist suggests evolution to have occurred in stages. There are not many prominent fossils to trace this evolution, but only fragments of skeletons and antlers that might be easily confused with false antlers of non-cervid species.
The ruminants, ancestors of the Cervidae, are believed to have evolved from Diacodexis, the earliest known artiodactyl (even-toed ungulate), 50–55 Mya in the Eocene. Diacodexis, nearly the size of a rabbit, featured the talus bone characteristic of all modern even-toed ungulates. This ancestor and its relatives occurred throughout North America and Eurasia, but were on the decline by at least 46 Mya. Analysis of a nearly complete skeleton of Diacodexis discovered in 1982 gave rise to speculation that this ancestor could be closer to the non-ruminants than the ruminants. Andromeryx is another prominent prehistoric ruminant, but appears to be closer to the tragulids.
The formation of the Himalayas and the Alps brought about significant geographic changes. This was the chief reason behind the extensive diversification of deer-like forms and the emergence of cervids from the Oligocene to the early Pliocene. The latter half of the Oligocene (28–34 Mya) saw the appearance of the European Eumeryx and the North American Leptomeryx. The latter resembled modern-day bovids and cervids in dental morphology (for instance, it had brachyodont molars), while the former was more advanced. Other deer-like forms included the North American Blastomeryx and the European Dremotherium; these sabre-toothed animals are believed to have been the direct ancestors of all modern antlered deer, though they themselves lacked antlers. Another contemporaneous form was the four-horned protoceratid Protoceras, that was replaced by Syndyoceras in the Miocene; these animals were unique in having a horn on the nose. Late Eocene fossils dated approximately 35 million years ago, which were found in North America, show that Syndyoceras had bony skull outgrowths that resembled non-deciduous antlers.
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Fossil evidence suggests that the earliest members of the superfamily Cervoidea appeared in Eurasia in the Miocene. Dicrocerus, Euprox and Heteroprox were probably the first antlered cervids. Dicrocerus featured single-forked antlers that were shed regularly. Stephanocemas had more developed and diffuse ("crowned") antlers. Procervulus (Palaeomerycidae), in addition to the tusks of Dremotherium, possessed antlers that were not shed. Contemporary forms such as the merycodontines eventually gave rise to the modern pronghorn.
The Cervinae emerged as the first group of extant cervids around 7–9 Mya, during the late Miocene in central Asia. The tribe Muntiacini made its appearance as Muntiacus leilaoensis around 7–8 Mya; The early muntjacs varied in size–as small as hares or as large as fallow deer. They had tusks for fighting and antlers for defence. Capreolinae followed soon after; Alceini appeared 6.4–8.4 Mya. Around this period, the Tethys Ocean disappeared to give way to vast stretches of grassland; these provided the deer with abundant protein-rich vegetation that led to the development of ornamental antlers and allowed populations to flourish and colonise areas. As antlers had become pronounced, the canines were no more retained or were poorly represented (as in elk), probably because diet was no more browse-dominated and antlers were better display organs. In muntjac and tufted deer, the antlers as well as the canines are small. The tragulids, however, possess long canines to this day.
With the onset of the Pliocene, the global climate became cooler. A fall in the sea-level led to massive glaciation; consequently, grasslands abounded in nutritious forage. Thus a new spurt in deer populations ensued.The oldest member of Cervini,Cervocerus novorossiae, appeared around the transition from Miocene to Pliocene (4.2–6 Mya) in Eurasia; cervine fossils from early Pliocene to as late as the Pleistocene have been excavated in China and the Himalayas. While Cervus and Dama appeared nearly 3 Mya, Axis emerged during the late Pliocene–Pleistocene. The tribes Capreolini and Rangiferini appeared around 4–7 Mya.
Around 5 Mya, the rangiferines Bretzia and Eocoileus were the first cervids to reach North America. This implies the Bering Strait could be crossed during the late Miocene–Pliocene; this appears highly probable as the camelids migrated into Asia from North America around the same time. Deer invaded South America in the late Pliocene (2.5–3 Mya) as part of the Great American Interchange, thanks to the recently formed Isthmus of Panama, and emerged successful due to the small number of competing ruminants in the continent.
Large deer with impressive antlers evolved during the early Pleistocene, probably as a result of abundant resources to drive evolution. The early Pleistocene cervid Eucladoceros was comparable in size to the modern elk.Megaloceros (Pliocene–Pleistocene) featured the Irish elk (M. giganteus), one of the largest known cervids. The Irish elk reached 2 metres (6.6 ft) at the shoulder and had heavy antlers that spanned 3.6 metres (12 ft) from tip to tip. These large animals are thought to have faced extinction due to conflict between sexual selection for large antlers and body and natural selection for a smaller form. Meanwhile, the moose and reindeer radiated into North America from Siberia.

The largest deer in all time was Cervalces latifrons

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Cervalces latifrons, the broad-fronted moose, was a large,
moose-like deer of the holarctic regions of Europe and Asia dating from the Pleistocene epoch. It is believed to be the largest species of deer that ever existed and is known only from its fossil remains. It was a species of the genus Cervalces.
Cervalces latifrons was first described by Mr Randall Johnson in 1874. A frontal bone attached to part of an antler of a previously unknown species of deer was found at low tide on the beachfront at Happisburgh, Norfolk, in the "Forest Bed". Johnson, who retained the specimen in his collection, named it Cervus latifrons Cervus being the only genus of deer known at that time. The specific name "latifrons" refers to the wide frontal bone of this large species. The morphology of the animal as deduced from this fossil and from others later found in this formation and on the Continent differs little from modern moose. It was later placed in the genus Cervalces which it shares with the also extinct Cervalces scotti from North America. The antlers of the males had short beams and large palmate lobes with up to ten large points. They were probably for display purposes to impress the female rather than for fighting because these moose are believed to have roamed as solitary individuals. Cervalces latifrons is probably the largest species of deer that has ever existed, with a shoulder height of 2.1 m (6 ft 11 in). It was about the same size as the American bison (Bison bison) and weighed about twice as much as the Irish elk (Megaloceros giganteus) but the span of its antlers at 2.5 m (8 ft 2 in) was smaller than that of the elk.
Fossil remains of this deer are known from northern Europe and Asia but have not been found in the Iberian Peninsula, Italy south of the Apennines, Croatia or Greece. In the United Kingdom, it is known only from the Cromer Forest Bed Formation. This is exposed at intervals along the coast of Norfolk and Suffolk and forms low cliffs between Cromer and Great Yarmouth. The holotype came from here. It is believed that Cervalces latifrons resembled its modern moose relations and lived in tundra, steppes, coniferous forests and swamps. It probably avoided deciduous forests because of the inconvenience that would be caused by its wide horns when moving among bushes and saplings. Like its living relatives, it is likely to have lived a solitary life. It is believed to have fed on rough herbage and plants growing around lakes and swamps.Further remains of Cervalces latifrons have been recovered from Sйnиze (Haute-Loire, France), Mauer (Baden-Wьrttemberg, Germany), Bilshausen (Niedersachsen, Germany), Mosbach (Hessen, Germany), SьЯenborn (Thьringen, Germany), Ranica (Lombardy, Italy), Leffe (Lombardy, Italy) and Crostolo Creek (Emilia-Romagna, Italy) and extensively from Siberia.
Fossils of large moose-like deer found in Siberia dating from the most recent glaciation are fragmentary and lack intact skulls and complete antlers but they have tentatively been identified as Cervalces latifrons. They had less advanced teeth, a more specialist muzzle and larger antlers that were bi-lobed and four pronged. They seem to have played a bridging role, crossing the land bridge to Alaska and eventually evolving into Cervalces scotti in North America. They were faced with predators well capable of tackling a moose, the brown bear in Siberia and the short-faced bear in Alaska. No such large carnivore was found in Europe at that time as the largest bear in that region, the cave bear, was herbivorous. In Europe, three paleospecies of moose seem to have followed each other chronologically. It is not clear whether Cervalces latifrons evolved into modern moose or whether it died out in the last glacial period.
A palaeobotanical study was made of clay found inside the skull of a specimen of Cervalces latifrons found at Fornaci di Ranica in northern Italy dating back to the early Pleistocene. The site was fluvial deposits in the basin of the Serio River. The infrared spectrum of the clay and the pollen grains found in it were compared with a previously available chronological sequence of pollens from sediments in the area. The results suggest that the vegetation in the region at the time in which the moose lived consisted of sparse coniferous forests with Pinus sylvestris and Pinus mugo, steppes and grassland. In the immediate vicinity, it correlated with a retreat of forest cover and an increase in herbaceous ground cover. The valley bottoms probably had standing water, marsh vegetation, moist meadows, bushes and flowering plants. A morpho-functional analysis of Cervalces latifrons comparing it with its modern deer relatives, Cervus spp., suggests similarities in diet and in adaptations for living in a marshy environment with scattered scrub and debris.
Cervalces latifrons shares many anatomical features with its living relative the Eurasian elk (Alces alces) with similarities in its grinding molars, narrow jaw, large mouth cavity, elongated muzzle and premaxillary bones. It is likely to have had a similar diet of bark, leaves and shoots of trees such as willow, aspen, rowan, birch, oak, larch and pine. It would also have grazed herbaceous vegetation in the boggy areas on the floors of valleys. Its limbs were long and show adaptations allowing for locomotion at a fast trot known as "stilt-locomotion". This involves a long stride with a high elevation of the feet at each step. This gait is helpful for moving through bogs or deep snow. The toes could be spread widely which would have aided swimming and prevented the foot sinking deeply when walking in marshy conditions.


Seckond largest "mega deer" was
Sinomegaceros yabei
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Giant deer with palmate brow tines were placed either in a single genus, or those from west Eurasia were placed in Megaloceros and those from the east in Sinomegaceros, which implies local evolution. In order to see whether dispersals between the two areas may have occurred, we studied the morphology and interpreted the phylogeny of these deer.The phylogenetic model proposed does not support any dispersals between east and west after the appearance of the first species of each genus, but it does support the recognition of two separate genera.The ecological significance of some of the morphological characters is interpreted. Thicker molar enamel, reduced posterior molars, larger premolars and a P4 with a lesser degree of “molarisation” suggests that Megaloceros savini adapted to a diet that includes coarser and harder food. Elevated mandibular condyles, thin molar enamel, and P4 that are predominantly “molarized” suggest that Megaloceros giganteus and Sinomegaceros yabei shifted towards grazing larger quantities of not very hard food. Very robust metapodials evolved several times in western Eurasian giant deer: during the Early Pleistocene in the Megaloceros solilhacus group, not later than the late Middle Pleistocene in M. giganteus and it increased in the Late Pleistocene M. giganteus. Since the character did not evolve in the east Eurasian giant deer, it might be related to some aspect of the west Eurasian environment, that was not present in east Eurasia.


The extinct Irish elk (Megaloceros giganteus) and the stag-moose (Cervalces scotti) were of similar or of slightly larger size than the Alaskan moose.

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However, the Irish elk could have antlers spanning up to 4.3 m (14 ft) across, about twice the maximum span for a moose"s antlers. The Irish elk (Megaloceros giganteus) is an extinct species of deer in the genus Megaloceros and is one of the largest deer that ever lived. Its range extended across Eurasia, from Ireland to northern Asia and Africa. A related form is recorded from China during the Late Pleistocene. The most recent remains of the species have been carbon dated to about 7,700 years ago in Siberia. Although most skeletons have been found in Irishbogs, the animal was not exclusively Irish and was not closely related to either of the living species currently called elk - Alces alces (the European elk, known in North America as the moose) or Cervus canadensis (the North American elk or wapiti). Early phylogenetic analyses supported the idea of a sister-group relationship between fallow deer and the Irish Elk.However, newer morphological studies prove that the Irish elk is more closely related to its modern regional counterparts of the Red Deer (Cervus elaphus). For this reason, the name "Giant Deer" is used in some publications.

The Irish Elk evolved throughout the last few million years during the Glacial Periods, specifically the Pleistocene Epoch. Once established, the elk spread throughout Europe, northern Asia and Africa, and some parts of China. Physically, the Irish Elk was the heaviest known member of the “Old World deer”, a division of the subfamily Cervinae whose groups the ”Old World deer” and “New World deer” are distinguished by foot structure rather than geographical origin. Most remains of Irish Elk date from between 11,750 BP (Before Present)-with the first Megaloceros giganteus appearing about 400,000 years ago-and 10,950 BP.Studies have shown they possibly evolved from M. antecedens. The earlier taxon — sometimes considered a paleosubspecies M. giganteus antecedens — is similar but had more complex and compact antlers.
The Irish Elk stood about 2.1 metres (6.9 ft) tall at the shoulders carrying the largest antlers of any known cervid (a maximum of 3.65 m (12.0 ft) from tip to tip and weighing up to 40 kg (88 lb)). In body size, the Irish Elk matched the extant moose subspecies of Alaska (Alces alces gigas) as the largest known deer. The Irish Elk is estimated to have attained a total mass of 540–600 kg (1,190–1,320 lb), with large specimens having weighed 700 kg (1,500 lb) or more, roughly similar to the Alaskan Moose. A significant collection of M. giganteus skeletons can be found at the Natural History Museum in Dublin.
The size of Irish Elk antlers are distinctive. Scientists have proposed multiple theories regarding the evolution of these antlers. One theory is that their antlers, under constant and strong sexual selection, increased in size because males were using them in combat for access to females. Thus, it is hypothesized that they eventually became so unwieldy that the Irish Elk could not carry on the normal business of life and so became extinct. It was not until Stephen Jay Gould"s important 1974 essay on Megaloceros that this theory was tested rigorously.

Gould demonstrated that for deer in general, species with a larger body size have antlers that are more than proportionately larger, a consequence of allometry, or differential growth rate of body size and antler size during development. Irish Elk had antlers of the appropriate size in correlation to their massive bodies. This does not mean that sexual selection played no part in maintaining large antler size, only that the antlers of the species" ancestors were already large to begin with. Indeed, Gould concluded that the large antler size and their position on the skull was very much maintained by sexual selection: they were morphologically ill-suited for combat between males, but their position was ideal to present them to intimidate rivals or impress females. Unlike other deer, M. giganteus did not even have to turn its head to present the antlers to best effect, but could accomplish this by simply looking straight ahead.The size of antlers has also been attributed to the health of the Irish elk. "If the Irish elk responded to nutritional restriction as red deer do, a huge and well-fed stag with 40 kg antlers (the near maximal size would have had 20 to 28 kg antlers under poor conditions. These estimates are within the range of extant moose Alces alces antlers.More typical prime stags with 35 kg antlers would have had 18 to 25 kg antlers in times of nutritional stress.A linear measure of antler size (basal circumference), however, was reduced even further to 41% of the mainland mean. Because basal circumference is highly correlated with other linear measures of antler size, such a decrease indicates that insular antler mass dropped to 1/14th of the mainland antler mass. This reduction in antler mass is 2.7 times more extreme than expected given the allometric relationship between antler and body masses in red deer and demonstrates a rapid evolution of smaller antlers. A similar change in a typical Irish elk population with prime stags having 35 kg antlers would result in antler weights of 13 kg or less in worsening climatic conditions. This estimate is within the range of extant wapiti/red deer (Cervus spp.) antler weights. It has been noted that Irish elk stags in more adverse environments had smaller bodies and relatively even smaller antlers, but proponents of the antler-extinction hypothesis have not addressed the possibility of rapid evolutionary reduction in antler size. We expect that the antlers of the Irish elk should have been able to evolve rapidly in the face of selection for smaller and less expensive sizes. This conclusion is supported by the great diversity of Irish elk antler forms found among different populations at different times, including compact upright orientations possibly from populations inhabiting more heavily wooded environments suggesting the evolutionary malleability of Irish elk antlers." In 1987, Kitchener presented evidence that Irish Elk antlers were in fact used for fighting. In addition, the Irish elk"s antlers had several functions such as being a display for attraction of females and dominance of rival males.The elks shed their antlers and re-grew a new pair during mating season. Ultimately, the decrease in energy intake by the Late Pleistocene, influenced the ability to produce for Irish elk females.
Traditionally, discussion of the cause of their extinction has focused on the antler size (rather than on their overall body size), which may be due more to their impact on the observer than any actual property. Some have suggested hunting by humans was a contributing factor in the demise of the Irish Elk, as may have been the case with other prehistoric megafauna, even assuming that the large antler size restricted the movement of males through forested regions or that it was by some other means a "maladaptation". Others assume the ultimate cause of extinction may have been the adaptations for mineral metabolism that were beneficial to the Irish elk until vegetation changed. But given the difficulty of recovering quantitative records of human hunting impacts from the sub-fossil record alone, the role of humans in the extinction of the Irish Elk is not yet clear.
However, the most recent specimen of M. giganteus in northern Siberia, dated to approximately 7,700 years ago - well after the end of the last glacial period - shows no sign of nutrient stress. They come from a region with a continental climate where the proposed vegetation changes had not (yet) occurred.


The stag-moose (Cervalces scotti) was a large moose, with a muzzle more closely resembling that of a typical deer, of North America during the Pleistocene epoch It is the only known North American member of the genus Cervalces.
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It was slightly larger than the moose, with an elk-like head, long legs, and complex, palmate antlers. Cervalces scotti reached 2.5 m (8.2 ft) in height and a weight of 708.5 kg (1,562 lb). The stag-moose resided in North America during an era with other Megafaunas such as the woolly mammoth, ground sloth, long horn bison, and saber toothed cat. The species went extinct approximately 11,500 years ago, toward the end of the most recent ice age, as part of a mass extinction of large North American mammals.

The first evidence of the stag-moose found in modern times was discovered at Big Bone Lick, Kentucky by William Clark, circa 1805. A more complete skeleton was found in 1885 by William Barryman Scott in New Jersey. Mummified remains have also been found.
The ancestor of the stag-moose is believed to have evolved in the Eurasian continent. The stag-moose or Cervalces scotti is believed to be related to the Cervalces latifrons, another similar species that went extinct around the same time as the stag-moose. The stag-moose is thought to have fulfilled a similar niche to a modern day moose. The stag-moose frequented wetlands, as well as woodlands and forests and inhabited by creatures such as the woodland musk-ox, and the giant beaver. in a range from southern Canada to Arkansas and from Iowa to New Jersey. Just like its modern day counterpart, the stag moose is a herbivore with a diet of vegetation and plants. The stag moose and the modern day moose shared common predators. Some possible main predators of the stag moose consisted of the grey wolf, the dire wolf, and the brown bear. Often, the brown bear would hunt the young stag-moose rather than going after the adults. Another possible predator of the stag-moose is the American lion which had a preference in deer like animals. Near the conclusion of the Pleistocene period, humans began hunting the Cervalces scotti as a source of meat.As the glaciers retreated, moose (which had crossed the Bering land bridge from Asia) may have populated its habitat and caused its extinction by competition. Although there is no paleontological evidence that it was associated with humans, other theories for its extinction have been proposed. Notably, there is speculation that hunting by newly arrived humans caused the extinction of the stag-moose and other large mammals.Additionally, some have proposed a sudden extinction by disease, brought by small mammals in association with humans. The oldest known fossil of the stag-moose was found in the bed of the Skunk River in Iowa, with the specimen dating back approximately 30,000 years ago. The area in which the fossil was found and the date implies that the stag-moose lived before a massive ice sheet covered the area in which it inhabited, which could also be a possible cause of its extinction. Since the stag-moose resides in a woodland habitat, climate change and loss of natural pastures also could have played a role in its extinction.
Stag-moose, although extinct, had many adaptations that helped them to thrive and survive. The stag-moose grew its antlers and had them drop off during the winter time. The antlers allowed the stag-moose to appear much larger and more intimidating than it really was. The antlers could grow to about six feet in length. Defense wasn’t the only use for the antlers, however, the antlers were used in male on male fighting while competing for a mate. It is a possibility that the antlers were developed to assist the stag-moose while looking for food in trees. The hooves developed by the stag-moose were very sharp and were used to break up ice and snow that were in the way of possible food on the ground. They were also very helpful in traveling over the extreme conditions in which the stag-moose lived. Stag-moose had quite a few behavior adaptations as well. The creatures were known for acting very carefully when sensing danger. This included not making any noises or sudden movements. Although very large, these stag-moose often times chose not to fight with its predators. In addition, the stag-moose were very quick to protect their young in the face of danger. This allowed most calves to grow into adults without much trouble. Remains of the stag-moose found in modern-day Ohio have suggested that stag-moose and Homo sapiens could have possibly interacted. Fossils of both the stag-moose and other large extinct mammals in the area suggest that the stag-moose may have been a frequent target of early human hunters.
The stag-moose, like several other members of its genus, probably lived in marshes and bogs, as well as spruce-taiga floral communities. There were also surroundings ranging from tundra–mixed coniferous forests to deciduous woodlands. These sedges and willows may have not have been suitable food products, but they provide an imagery of the ecology of the elk-moose. The change in flora and fauna due to complete deglaciation probably also affected the living conditions of the stag-moose in states like Iowa and Wisconsin, where the stag-moose was found at more than 20 sites None of these sites, however, has any evidence that the stag-moose interacted with humans, furthering evidence that the extinction of the stag-moose is not comparable to that of large herbivores that were greatly affected by hunting. The stag moose reproduced more often than megaherbivores, and so the hypothesis is that the stag-moose"s disappearance is linked to the emergence of the "true moose" (Alces alces), instead.Another reason for extinction could be the competitions of several herbivorous artiodactyls, like the Bison in the new grassland ecosystem which replaced the spruce forest environment.


Libralces gallicus

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Libralces was a genus of Eurasian deer that lived during the Pliocene period. The genus" main claim to fame are their 2+ meter wide antlers, comparable in size with those of Megaloceros. Libralces gallicus lived in the Pliocene epoch, about 2 million years ago. Libralces gallicus came from the warm savannahs of Pliocene Europe, with the best preserved skeletons being found in southern France. Libralces gallicus was 1.25 times larger than the Alaskan moose in linear dimensions, making it nearly twice as massive. Libralces gallicus had many striking differences compared to its modern descendants. It had a longer, narrower snout and a less-developed nasal cavity, more resembling that of a modern deer, lacking any sign of the modern moose-snout. Its face resembled that of the modern Wapiti. However, the rest of its skull structure, skeletal structure and teeth bore strong resemblance to those features that are unmistakable in modern Moose, indicating a similar diet. Its antlers consisted of a 2 1/2 meter long horizontal bar, with no tines, ending in small palmations. Its skull and neck structure suggest an animal that fought using high-speed impacts, much like the dall sheep, rather than locking and twisting antlers the way modern moose combat. Their long legs and bone structure suggest an animal that was adapted to running at high speeds over rough terrain. It is assumed, moreover, the presence of Cervalces upper canines. In the southern areas of northern Eurasia, where this species lived in the Late Pliocene, dominated forest-steppe and steppe landscapes of the modern type of savannah, and the big horns could be used in "demonstration" purposes, that as time involves dwelling in the open with good visibility.














Тагове:   Moose,   сова,   prehistoric animals,   giant animals,   beast,   largest animals,   encyclopedia,   deer,   elk,   antlers,


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