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Post by arctozilla on Jul 1, 2022 11:36:51 GMT -5
The bear dogs (scientifically named “Amphicyonids”) are a group of extinct carnivorans closely related to dogs and bears and were the first carnivorans to evolve large bodies. They ruled the plains of Eurasia and North America hunting large preys like chalichoteres and rhinos.
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Post by arctozilla on Jul 1, 2022 11:48:11 GMT -5
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Post by arctozilla on Jul 1, 2022 11:52:00 GMT -5
Ecomorphology of the giant bear-dogs Amphicyon and Ischyrocyon Giant bear-dogs of the genera Amphicyon and Ischyrocyon (Carnivora, Amphicyonidae, Amphicyoninae) were the largest carnivorans in North America during middle and late Miocene (17.5–8.8 Mya) with a dental and skeletal morphology that combined features found in living Ursidae, Canidae, and Felidae. This study tests previously proposed models of diet and hunting behaviour of these extinct carnivorans. Relative grinding area (RGA) of lower molars and wear pattern on upper molars suggest that bear-dogs were carnivorous. Amphicyon and Ischyrocyon possessed skeletal features of both ambush (short distal limb segments) and pursuit (caudally bent olecranon process of ulna) living predators. Therefore, bear-dogs probably pursued their prey (mediportal ungulates) for a longer distance but at a slower speed than do living ambush predators. Upon catching up to its prey a bear-dog probably seized it with powerfully muscled forelimbs and killed it by tearing into its ribcage or neck with canines set in a narrow rostrum. www.researchgate.net/publication/40661208_Ecomorphology_of_the_giant_bear-dogs_Amphicyon_and_Ischyrocyon
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Post by arctozilla on Jul 1, 2022 11:58:16 GMT -5
A new gigantic carnivore (Carnivora, Amphicyonidae) from the late middle Miocene of France Serravallian terrestrial vertebrates are very uncommon in the northern margin of the Pyrenean Mountains. A mandible of a new large sized amphicyonid (ca. 200 kg) is here described from the marine deposits of Sallepisse (12.8–12.0 Mya). Despite that this new taxon is close in size to some European amphicyonids from the Miocene (e.g., Amphicyon, Megamphicyon, and Magericyon), the unique morphology of its p4, unknown in this clade, allows the erection of the new genus Tartarocyon cazanavei nov. gen. & sp. This taxon may be derived from a Cynelos-type amphicyonine. The description of this new taxon highlights the erosion of the ecological and morphological diversity of the Amphicyonidae in response to well-known Miocene events (i.e., Proboscidean Datum Event, Middle Miocene Climatic Transition, Vallesian Crisis). peerj.com/articles/13457/
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Post by Gorilla king on Jul 1, 2022 13:46:49 GMT -5
Amphicyonidae
Abstract
The Amphicyonidae occur in North America from late Eocene (~40 Ma) to early late Miocene (~9 Ma), a span of 31 million years. In the North American land mammal biochronology, this diverse family extends from the Duchesnean to the end of the Clarendonian and is especially well represented in the Miocene (~5-24 Ma). In the Old World, amphicyonids survive no longer than in North America: The last European records are Vallesian (Dinotheriensande, Mainz Basin, Germany, Kuss, 1965, Tobien, 1980; Vallés-Penédes Basin, Spain, Crusafont-Pairó and Kurten, 1976), and the last representative may occur at about 9 Ma at Kohfidisch, Austria (latest Vallesian, Beaumont, 1984; Mein, 1989). The group is extinct by 13 Ma in eastern Asia and by about 7 Ma on the Indian subcontinent (Barry and Flynn, 1989). In Africa, amphicyonids are no longer evident after about 11 Ma, but future discoveries may improve this sparse record as Miocene faunas become better known. Two North American subfamilies (Daphoeninae, Amphicyoninae) have been recognized, but as commonly employed they are in fact arbitrary groupings without well-founded support. Because the Amphicyoninae simply succeeded the Daphoeninae in time, the subfamilies appeared to be evolutionary grades, but the grades in North America were without substantiated phyletic connection between ancestral and descendant genera. In this chapter I advance a new hypothesis to account for the evolution and geographic distribution of amphicyonids. This hypothesis uses an improved knowledge of biogeography of amphicyonid fossils on the northern continents as a significant new source of information in deciphering their phylogenetic relationships, while at the same time recognizing the lack of reliable synapomorphic traits to ally subgroups within the family. Simply stated, the distribution of amphicyonid fossils in North America and Europe suggests the existence of two separate radiations of beardogs, both initiated in the late Eocene/Oligocene, the European termed "amphicyonine," the North American identified as "daphoenine." Thus I employ the subfamilies as monophyletic groups arising and radiating in different geographic areas, yet sharing a common ancestral popUlation (the stem amphicyonid stock) sometime in the Eocene. The distribution of amphicyonid genera in time in North America and Europe is central to the proposed concept of amphicyonid evolution advocated in this chapter: North American daphoenines are endemic to the New World, first appearing about 40 Ma and continuing to about 17 Ma. European amphicyonines originate about the same time (40 Ma) in the Old World and continue to 9 Ma in Europe, but amphicyonine lineages periodically invade North America as immigrants during the late Oligocene and Miocene. All native daphoenines are extinct by 17 Ma and are replaced by Old World amphicyonines. From this point in time until their North American extinction ( ...... 9 Ma), the beardogs of the New World are all derived from migrant Old World amphicyonines whose roots occur in European lineages. I also recognize two additional subfamilies, the North American Temnocyoninae and European Haplocyoninae. The dental specializations of these two groups provide distinctive synapomorphic features that allow them to be identified and set apart. New World temnocyonines are plausibly derived from a haplocyonine immigrant in the late Oligocene, although each subfamily evolves its own unique dental morphologies in Europe and North America. Abundant amphicyonid fossils have been found in both Europe and North America where the family displays a progression from generalized species of small body size to very large forms of a more specialized nature. Amphicyonids are also known from Asia and Africa where their remains are rare but of great interest in demonstrating affinity to European taxa. No amphicyonids are known from South America, and their extinction in North America preceded the interchange of faunas that occurred in the Americas during the PlioPleistocene.
www.researchgate.net/publication/326391901_Amphicyonidae
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Post by Gorilla king on Jul 1, 2022 13:54:03 GMT -5
Temnocyon
Temnocyon is an extinct genus of bear-dogs endemic to North America. It lived from the Oligocene to Early Miocene approximately 30.8—20.4 mya, existing for about 11 million years.[1]
The first fossils are recorded in North America at Logan Butte in the John Day beds of Oregon, in the Sharps Formation of the Wounded Knee area, South Dakota, and in the Gering Formation at Wildcat Ridge, Nebraska. These early temnocyonines attained the size of coyotes or small wolves (15–30 kg) and are identified by a uniquely specialized dentition. The last documented occurrences of temnocyonines are found in sediments in northwest Nebraska and southeastern Wyoming.[2]
en.m.wikipedia.org/wiki/Temnocyon
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Post by arctozilla on Jul 1, 2022 15:18:14 GMT -5
Intercontinental Migration of Large Mammalian Carnivores: Earliest Occurrence of the Old World Beardog Amphicyon (Carnivora, Amphicyonidae) in North America North American amphicyonid carnivorans are prominent members of the mid-Cenozoic terrestrial carnivore community during the late Eocene to late Miocene (Duchesnean to Clarendonian). Species range in size from <5 kg to >200 kg. Among the largest amphicyonids are Old and New World species of the genus Amphicyon: A. giganteus in Europe (18–~15? Ma) and Africa, A. ingens in North America (15.9–~14.2 Ma). Amphicyon first appears in the Oligocene of western Europe, surviving there until the late Miocene. Migration to Africa and North America takes place in the early Miocene. The genus occurs in the Arrisdrift fauna (Namibia) of southwest Africa, indicating migration south through the length of the African continent by the mid-Miocene. Its occurrence in Asia is problematical because of the tendency to place any moderately large Asian amphicyonid in the genus, and because of the fragmentary nature of many fossils. Here I report the earliest North American occurrences of Amphicyon (18.8–~17.5 Ma), assigning these individuals to a new and previously undescribed species, Amphicyon galushai, from early Hemingfordian sediments of western Nebraska and north-central Colorado. In the New World, small early Hemingfordian Amphicyon galushai is probably ancestral to larger late Hemingfordian A. frendens, and to the terminal and largest species of the genus, early to mid-Barstovian A. ingens. Diagnostic basicranial and dental traits place these species in the Amphicyonidae, and demonstrate a close relationship of the North American lineage to the type species of the genus, A. major, from Sansan, France. Amphicyon galushai is known from a complete adult skull, a partial juvenile skull, three mandibles, and the isolated teeth and postcranial elements of ~15 individuals, all from the early Miocene Runningwater Formation of western Nebraska. The species also is represented by a crushed rostrum from the Troublesome Formation, north-central Colorado. Basicranial, dental, and postcranial anatomy distinguish A. galushai from its contemporary in the Runningwater Formation, the large digitigrade beardog Daphoenodon. The Runningwater Formation contains the last occurrence of Daphoenodon in North America and the first occurrence of Amphicyon; the overlap in stratigraphic ranges of these two carnivores provides a useful early Miocene biostratigraphic datum. The two amphicyonids occur together in the same quarries, associated with canid, mustelid, and rare procyonid carnivores, which are much smaller animals. The North American species of Amphicyon (A. galushai, A. frendens, A. ingens) most likely adopted ecological roles similar to the large living felids (in particular, the lion Panthera leo). Their robust skeleton with powerful forelimbs, massive clawed feet, heavily muscled jaws with large canines, and a composite crushing/shearing dentition suggest a mobile predator that most likely stalked and ambushed prey from cover, overpowering its victims through sheer size and strength. digitalcommons.unl.edu/geosciencefacpub/545/
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Post by Gorilla king on Jul 1, 2022 16:02:22 GMT -5
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Post by arctozilla on Jul 2, 2022 3:33:48 GMT -5
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Post by arctozilla on Jul 2, 2022 3:45:01 GMT -5
Morphofunctional analysis of the postcranium of Amphicyon major (Mammalia, Carnivora, Amphicyonidae) from the Miocene of Sansan (Gers, France) compared to three extant carnivores: Ursus arctos, Panthera leo, and Canis lupus The morphology of the whole forelimb of Amphicyon major is very much like that of a bear. As in extant bears, an accessory fossa and a wide neck characterise the scapula of the fossil taxon. These two features as well as the broad spinati fossa suggest a heavy scapular musculature. In addition, abductors (deltopectoral muscles) and flexors (biceps + brachialis) were also powerfully developed. The ball-shaped humeral head, higher than both tubercles, indicates a mobile shoulder joint. The elbow joint is very similar to that of a bear, indicating an abducted humerus with usual flexed positions and a maximised humeroulnar stability in extensions. sciencepress.mnhn.fr/en/periodiques/geodiversitas/32/1/analyse-morphofonctionnelle-du-squelette-postcranien-d-amphicyon-major-mammalia-carnivora-amphicyonidae-du-miocene-de-sansan-gers-france-compare-trois-carnivores-actuels-ursus-arctos-panthera-leo-et-canis-lupus
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Post by arctozilla on Jul 2, 2022 3:48:37 GMT -5
Comparative Anatomy of the Shoulder Region in the Late Miocene Amphicyonid Magericyon anceps (Carnivora): Functional and Paleoecological Inferences Thus, the combined contraction of the muscles subscapularis and subscapularis minor would improve the shoulder joint stability during the grasping and pulling actions in ursids and amphicyonids (Hunt 2009), as it has been also proposed for P. flavus and S. batalleri (Salesa et al. 2008). In ursids, the development of both the postscapular fossa and the teresmajor process besides the mobile shoulder articulation and the overall powerful shoulder musculature have been related to the ability of this group for climbing trees, an activity that implies that part of the body weight is supported by the forelimbs (Davis 1949; Argot 2003, 2010), but also to other types of behavior, such as overturning stones and digging (Gambaryan 1974). www.researchgate.net/publication/264931438_Comparative_Anatomy_of_the_Shoulder_Region_in_the_Late_Miocene_Amphicyonid_Magericyon_anceps_Carnivora_Functional_and_Paleoecological_Inferences
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Post by arctozilla on Jul 3, 2022 14:53:26 GMT -5
Whence the beardogs? Reappraisal of the Middle to Late Eocene ‘Miacis’ from Texas, USA, and the origin of Amphicyonidae (Mammalia, Carnivora) Abstract The Middle to Late Eocene sediments of Texas have yielded a wealth of fossil material that offers a rare window on a diverse and highly endemic mammalian fauna from that time in the southern part of North America. These faunal data are particularly significant because the narrative of mammalian evolution in the Paleogene of North America has traditionally been dominated by taxa that are known from higher latitudes, primarily in the Rocky Mountain and northern Great Plains regions. Here we report on the affinities of two peculiar carnivoraforms from the Chambers Tuff of Trans-Pecos, Texas, that were first described 30 years ago as Miacis cognitus and M. australis. Re-examination of previously described specimens and their inclusion in a cladistic analysis revealed the two taxa to be diminutive basal amphicyonids; as such, they are assigned to new genera Gustafsonia and Angelarctocyon, respectively. These two taxa fill in some of the morphological gaps between the earliest-known amphicyonid genus, Daphoenus, and other Middle-Eocene carnivoraforms, and lend additional support for a basal caniform position of the beardogs outside the Canoidea. The amphicyonid lineage had evidently given rise to at least five rather distinct forms by the end of the Middle Eocene. Their precise geographical origin remains uncertain, but it is plausible that southern North America served as an important stage for a very early phase of amphicyonid radiation. royalsocietypublishing.org/doi/10.1098/rsos.160518
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Post by arctozilla on Jul 4, 2022 9:39:21 GMT -5
Amphicyon Ingens had the longest skull of all carnivorans.
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Post by arctozilla on Jul 4, 2022 10:30:40 GMT -5
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Post by arctozilla on Jul 4, 2022 10:35:57 GMT -5
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Post by arctozilla on Jul 4, 2022 10:48:56 GMT -5
Resource partitioning among top predators in a Miocene food web Abstract The exceptional fossil sites of Cerro de los Batallones (Madrid Basin, Spain) contain abundant remains of Late Miocene mammals. From these fossil assemblages, we have inferred diet, resource partitioning and habitat of three sympatric carnivorous mammals based on stable isotopes. The carnivorans include three apex predators: two sabre-toothed cats (Felidae) and a bear dog (Amphicyonidae). Herbivore and carnivore carbon isotope (δ13C) values from tooth enamel imply the presence of a woodland ecosystem dominated by C3 plants. δ13C values and mixing-model analyses suggest that the two sabre-toothed cats, one the size of a leopard and the other the size of a tiger, consumed herbivores with similar δ13C values from a more wooded portion of the ecosystem. The two sabre-toothed cats probably hunted prey of different body sizes, and the smaller species could have used tree cover to avoid encounters with the larger felid. For the bear dog, δ13C values are higher and differ significantly from those of the sabre-toothed cats, suggesting a diet that includes prey from more open woodland. Coexistence of the sabre-toothed cats and the bear dog was likely facilitated by prey capture in different portions of the habitat. This study demonstrates the utility of stable isotope analysis for investigating the behaviour and ecology of members of past carnivoran guilds. www.ncbi.nlm.nih.gov/pmc/articles/PMC3574434/
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Post by arctozilla on Jul 4, 2022 11:00:14 GMT -5
The first record of an amphicyonid (Mammalia : Carnivora) from Japan, and its implication for amphicyonid paleobiogeography A mammalian tooth from the lower Middle Miocene Korematsu Formation (ca. 16.3-15.6 Ma) within the Bihoku Group in Shobara City, Hiroshima Prefecture, southwestern Japan, is described and identified as a right upper first molar of the amphicyonid carnivore Ysengrinia sp. This is the first amphicyonid to be described from Far East Asia and it provides additional evidence for the carnivoran faunal connections between Europe-Asia-North America during the Early and early Middle Miocene. www.jstage.jst.go.jp/article/prpsj1997/1/4/1_4_311/_article/-char/ja/
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Post by Gorilla king on Jul 4, 2022 12:05:18 GMT -5
Amphicyon Ingens had the longest skull of all carnivorans. Nice find. Here we have a 680 kg (1499 lbs) kodiak bear specimen. This weight is based on its femur length though, so it might not be exact.
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Post by Gorilla king on Jul 4, 2022 12:42:34 GMT -5
Not really, according to the chart above, the largest specimen of Amphicyon Ingens had a skull length of 520 mm. The bear skull with the greatest length in history belongs to the cave bear (Ursus Ingressus/Ursus Kanivetz) with 57.14 cm (571.4 mm):
Reply #20:
beargorillarealm.proboards.com/post/432/thread
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Post by arctozilla on Jul 5, 2022 3:46:55 GMT -5
New fossils of Amphicyonidae (Carnivora) from the middle Miocene (MN6) site of Carpetana (Madrid, Spain) Herein, we present a study of an interesting sample of fossils of the giant amphicyonid Megamphicyon giganteus (Schinz, 1825) from the Spanish middle Miocene (MN6) site of Carpetana (Madrid city), obtained during public works for the Madrid underground in 2008. Although the dentition of this species is known from other sites, the postcranial bones are very poorly known, and the new material provides new data on the locomotor adaptations of this spectacular predator, and allows an estimation of its body mass, which would be around 600 kg. Surprisingly, despite this giant size, the morphology of both femur and tibia shows that this animal exhibited higher cursorial capacity than large extant carnivorans, such as bears, which together with a high degree of pronation/supination movement of the forearm, reveals adaptations of M. giganteus to occupy the niche of active top predator in middle Miocene ecosystems. sciencepress.mnhn.fr/en/periodiques/geodiversitas/42/15
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