Hyaenodonta Temporal range: Paleocene to late Miocene early (Suspected Late Cretaceous origin, but unconfirmed by fossils yet) [1] [2] | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Mirorder: | Ferae |
Clade: | Pan-Carnivora |
Order: | † Hyaenodonta Van Valen, 1967 [3] |
Subgroups | |
[see classification] | |
Synonyms | |
Hyaenodonta ("hyena teeth") is an extinct order of hypercarnivorous placental mammals of clade Pan-Carnivora from mirorder Ferae. [6] [7] Hyaenodonts were important mammalian predators that arose during the early Paleocene in Europe [8] and persisted well into the late Miocene. [9]
Hyaenodonts are characterized by long, often disproportionately large skulls, slender jaws, and slim bodies. They generally ranged in size from 30 to 140 cm at the shoulder. [10] While Simbakubwa kutokaafrika may have been up to 1,500 kg (3,300 lb) (surpassing the modern polar bear in size [11] ), this estimate is suspect due to being based on skull-body size ratios derived from felids, which have much smaller skulls for their body size. Other large hyaenodonts include two close and later-surviving relatives of Simbakubwa, Hyainailouros and Megistotherium (the latter likely being the largest in the group), and the much earlier-living Hyaenodon gigas (the largest species from genus Hyaenodon ), which may have been as large as 1.4 m high at the shoulder, 3.0 m long and weighed about 330 kg. Most hyaenodonts, however, were in the 5–15 kg range, equivalent to a mid-sized dog. [12] The anatomy of their skulls show that they had a particularly acute sense of smell, while their teeth were adapted for shearing, rather than crushing. [10]
Hyaenodonts were ancestrally plantigrade, but the later, larger forms were generally digitigrade or semidigitigrade. Because of their size range, it is probable that different species hunted in different ways, which allowed them to fill many different predatory niches, with small or medium-sized forms filling roles similar to mustelids or smaller felids of today while the larger forms functioned as apex predators focusing on larger prey, wielding their mighty jaws as their principal weapon as they lacked grasping forelimbs. The carnassials in a hyaenodonts are generally the second upper and third lower molars. However, some hyaenodonts possessed as many as three sequential pairs of carnassials or carnassial-like molar teeth in their jaws. [13] Hyaenodonts, like all creodonts, lacked post-carnassial crushing molar teeth, such as those found in many carnivoran families, especially the Canidae and Ursidae, and thus lacked dental versatility for processing any foods other than meat. [13]
Hyaenodonts differed from Carnivora in that they replaced their deciduous dentition slower in development than carnivorans. [14] Studies on Hyaenodon show that juveniles took 3 to 4 years in the last stage of tooth eruption, implying a very long adolescent phase. In North American forms, the first upper premolar erupts before the first upper molar, while European forms show an earlier eruption of the first upper molar. [15]
At least one hyaenodont lineage, subfamily Apterodontinae, was specialised for aquatic, otter-like habits. [16]
Having evolved in Europe during the Paleocene, [8] hyaenodonts soon after spread into Africa and India, implying close biogeographical connections between these areas. [16] [17] Afterwards, they dispersed into Asia from either Europe or India, and finally, North America from either Europe or Asia. [18] [19]
They were important hypercarnivores in Eurasia, Africa, and North America during the Oligocene, but declined towards the end of the epoch, with almost the entire order becoming extinct by the close of the Oligocene. Several representatives of this order, including hyainailourids Megistotherium , Simbakubwa , Hyainailouros , Sectisodon , Exiguodon , Sivapterodon , Metapterodon , and Isohyaenodon , the prionogalid Prionogale , the teratodontid Dissopsalis and the youngest species of genus Hyaenodon, H. weilini , survived into or evolved during the Miocene, of which, only Dissopsalis survived long enough to go extinct at the close of the Miocene. [9] Traditionally, this has been attributed to competition with carnivorans, but no formal examination of the correlation between the decline of hyaenodonts and the expansion of carnivorans has been recorded, and the latter may simply have moved into vacant niches after the extinction of hyaenodont species. [20]
Hyaenodonts were considerably more widespread and successful than the oxyaenids, the other clade of mammals originally classified along with the hyaenodonts as part of Creodonta. [10] In 2015 phylogenetic analysis of Paleogene mammals, by Halliday et al., monophyly of Creodonta was supported and was placed in the clade Ferae, closer to Pholidota than to Carnivora. [21] However, order Creodonta is now considered to be a polyphyletic wastebasket taxon containing two unrelated clades assumed to be closely related (or ancestral) to Carnivora. [8] [14] [15] [16] [17] [22] [23] [24] [25] [26] [27]
Order: †Hyaenodonta(Van Valen, 1967)
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Creodonta is a former order of extinct carnivorous placental mammals that lived from the early Paleocene to the late Miocene epochs in North America, Europe, Asia and Africa. Originally thought to be a single group of animals ancestral to the modern Carnivora, this order is now usually considered a polyphyletic assemblage of two different groups, the oxyaenids and the hyaenodontids, not a natural group. Oxyaenids are first known from the Palaeocene of North America, while hyaenodonts hail from the Palaeocene of Africa.
Megistotherium is an extinct genus of hyaenodont belonging to the family Hyainailouridae that lived in Africa.
Hyaenodon ("hyena-tooth") is an extinct genus of carnivorous placental mammals from extinct tribe Hyaenodontini within extinct subfamily Hyaenodontinae, that lived in Eurasia and North America from the middle Eocene, throughout the Oligocene, to the early Miocene.
Ferae is a mirorder of placental mammals in grandorder Ferungulata, that groups together clades Pan-Carnivora and Pholidotamorpha.
Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified fourth upper premolar and the first lower molar. These teeth are also referred to as sectorial teeth.
Dissopsalis is a genus of teratodontine hyaenodonts of the tribe Dissopsalini. The older species, D. pyroclasticus, lived in Kenya during the middle Miocene, while the type species, D. carnifex, lived in Pakistan and India during the middle to late Miocene.
Pterodon is an extinct genus of hyaenodont in the family Hyainailouridae, containing five species. The type species Pterodon dasyuroides is known exclusively from the late Eocene to the earliest Oligocene of western Europe. The genus was first erected by the French zoologist Henri Marie Ducrotay de Blainville in 1839, who said that Georges Cuvier presented one of its fossils to a conference in 1828 but died before he could make a formal description of it. It was the second hyaenodont genus with taxonomic validity after Hyaenodon, but this resulted in taxonomic confusion over the validities of the two genera by other taxonomists. Although the taxonomic status of Pterodon was revised during the late 19th and early 20th centuries, it became a wastebasket taxon for other hyaenodont species found in Africa and Asia. Today, only the type species is recognized as belonging to the genus while four others are pending reassessment to other genera.
Hyainailouros ("hyena-cat") is an extinct polyphyletic genus of hyaenodont belonging to the family Hyainailouridae that lived during the early to middle Miocene, of which there were at least three species spread across Europe, Africa, and Asia.
Apterodon is an extinct genus of hyaenodontid mammals that lived from the late Eocene through the middle Oligocene epoch in Africa and Europe. It is closely related to the African Quasiapterodon, and together it, they comprise the hyainailurids subfamily Apterodontinae.
Galecyon ("polecat-dog") is an extinct genus of placental mammals from extinct order Hyaenodonta, that lived in Europe and North America during the early Eocene.
Hyainailouridae ("hyena-cats") is a family of extinct predatory mammals within the superfamily Hyainailouroidea within extinct order Hyaenodonta. Hyaenodontids arose during the middle Eocene and persisted well into the middle Miocene. Fossils of this group have been found in Asia, Africa, North America and Europe.
Teratodontinae is a subfamily of extinct hyaenodonts. Fossil remains of these mammals are known from Middle Eocene to Late Miocene deposits in Africa, the Arabian Peninsula, and Asia.
Isohyaenodon is an extinct polyphyletic genus of hyainailourid hyaenodont mammal from the subfamily Hyainailourinae). Remains are known from early to middle Miocene deposits in Kenya, East Africa.
Simbakubwa is an extinct genus of hyaenodonts to the family Hyainailourinae that lived in Kenya during the early Miocene.
Kerberos ("Cerberus") is an extinct genus of hyainailourid hyaenodonts in the subfamily Hyainailourinae, that lived in Europe. It contains the single species Kerberos langebadreae.
Sinopidae is an extinct family of predatory placental mammals from extinct order Hyaenodonta. Fossil remains of these mammals are known from early to middle Eocene deposits in North America, Europe and Asia.
Dissopsalini is an extinct tribe of teratodontid hyaenodonts. Fossil remains of these mammals are known from early to late Miocene deposits in Asia and Africa.
Apterodontinae is an extinct subfamily of hyainailourid hyaenodonts that lived in Africa and Europe during the late Eocene to middle Oligocene.
Hyainailourinae ("hyena-cats") is an extinct subfamily of hyainailourid hyaenodonts that lived in Africa, Asia, North America and Europe from the middle Eocene to middle Miocene. They appeared in Africa about 47.8 Ma ago and soon after spread as far as East Asia.
Myacyon is an extinct genus of large sized carnivoran mammals, belonging to the family Amphicyonidae, that lived in Africa during the Miocene epoch. Due to the limited scope and fragmentary nature of the severely damaged holotype, as well as the illustrations in its descriptions, which have been called inadequate, usage of this genus poses serious issues. However, it is notable for being one of the last surviving members of its family and its adaptions to hypercarnivory. Its relationships to other amphicyonids are obscure, and it is not closely related to Bonisicyon, the other late surviving African genus, although it has been proposed that it descends from a species of Cynelos or Namibiocyon.