Wabulacinus Temporal range: Early Miocene, Possible Late Oligocene record | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Infraclass: | Marsupialia |
Order: | Dasyuromorphia |
Family: | † Thylacinidae |
Genus: | † Wabulacinus Muirhead, 1997 |
Type species | |
†Wabulacinus ridei Muirhead, 1997 | |
Other species | |
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Synonyms | |
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Wabulacinus is a poorly known genus of thylacinid marsupial from Early Miocene and possibly Late Oligocene deposits at the Riversleigh World Heritage Area in Queensland. It consists of two species, the type species W. ridei and W. macknessi. The snout of W. ridei was relatively broad, while W. macknessi had a noticeably elongated skull. Both species are thought to have been hypercarnivorous.
Wabulacinus was first described in 1997, emerging from an examination undertaken by Jeanette Muirhead of thylacinid fossils collected at the Riversleigh World Heritage Area in northwestern Queensland, Australia. The holotype specimen of W. ridei (QM F16851) is a fragment of the right maxilla. A second specimen, a left dentary fragment, was also assigned to the species as well. All fossils are a part of the paleontological collection at the Queensland Museum. [1]
Five years prior to the description of the type species, Muirhead named a new species of Thylacinus , T. macknessi, based on material collected from Riversleigh deposits. At the time, only the back portion of the holotype dentary was known. [2] In late 1993, the remaining half of this dentary was found in a limestone block and was later described in 1995. [3] A study published by Churchill and colleagues in 2024 reassigned T. macknessi to the genus Wabulacinus, forming the new combination W. macknessi. [4]
The generic name combines the Waanyi word "wabula" (long ago) and the Ancient Greek stem word "-kynos" (dog), alluding to its canid-like resemblance. [1]
In 2003, Stephen Wroe reported a tooth referable to Wabulacinus sp. from older Riversleigh deposits, specifically the Late Oligocene White Hunter site. [5]
The skull of Wabulacinus is poorly known, with the only preserved material being a maxilla, two dentaries and isolated teeth. Based on the short size of the dentary, W. ridei probably had a relatively broad snout compared to W. macknessi. [6] The maxilla is represented by a fragment retaining the first two molars. The infraorbital foramen is positioned above where the posterior root of the third premolar would be, and is fully enclosed by the maxilla. Stylar cusps B and D on the first molar are completely absent, while the talon and protocone are both reduced in size. Both the preparacrista and centrocrista crests are almost parallel to each other. In addition, the first molar lacks a sulcus for the next molar. The second molar has a reduced stylar cusp D, while stylar cusp B is entirely absent. Posterior cingulids are present but poorly developed, whereas the buccal cingulids are well pronounced. [1]
The dentary of W. macknessi has diastema (gap) between the canine and premolar teeth, with two mental foramina positioned under the posterior root of the first premolar and the anterior root of the third premolar. [3] In contrast, W. ridei lacks diastema between its teeth and has only one mental foramen, which is just under the anterior root of the second premolar. [1] Both the upper and lower dentition retain anterior cingula. In addition, all molars display a longitudinal blade formed by the hypoconid being positioned lingually (towards the tongue) from the paracristid. The crest in front of the paracone (known as the preparacrista) is almost parallel to the tooth row. Similar to species of Thylacinus, the metaconid cusp is vestigial or completely absent. The molars of W. ridei are completely void of an entoconid cusp, whereas W. macknessi retains an entoconid on all molars except for the fourth lower molar. [4]
W. macknessi was a fairly large thylacinid for its time, with an estimated body weight of 6.7-9.0 kg (14.8-19.8 lbs). W. ridei was only slightly smaller, weighing up to 5.3-7.8 kg (11.7-17.2 lbs). [6]
In its initial description, the position of Wabulacinus within Thylacinidae was tested by performing a single most parsimonious tree. The results of the tree found that it was the sister taxon of the genus Thylacinus. [1] In 2014, palaeontologist Adam Yates also found support for this close relationship. [7] In 2019, Rovinsky and colleagues conducted three phylogenetic analyses, with the first analysis also confirming this assignment. The second analysis, however, recovered it in a polytomy, whereas the third and final analysis found that it claded with Thylacinus potens and Tyarrpecinus as sister group to Thylacinus. [6]
Thylacinus macknessi was initially thought to have been the basalmost species of Thylacinus. [1] However, most cladistic analyses, such as Murray & Megirian (2006a) and Yates (2014), have recovered a sister taxa relationship between it and the type species W. ridei. [7] [8] Churchill and colleagues (2024) showed support for this relationship in their phylogenetic analyses. As a result, the authors reassigned T. macknessi to Wabulacinus. [4]
The type species, W. ridei, is known only from the Early Miocene Camel Sputum site of Riversleigh, which has been radiometrically dated to ~18.5-17.0 Ma. In contrast, fossils of W. macknessi have been recovered from the similarly aged Neville’s Garden (18.5-17.7 Ma) and Mike’s Menagerie sites (~18.5-16.2 Ma). During this period of time, Australia’s climate would have been warm and permanently wet after shifting from a more cooler and drier setting in the Late Oligocene. [9] The environment inhabited by Wabulacinus consisted of open rainforest habitat. [10]
The Camel Sputum, Neville’s Garden and Mike’s Menagerie sites have also yielded the remains of the thylacinid Ngamalacinus timmulvaneyi , and the thylacoleonids Microleo , Lekaneleo roskellyae and Wakaleo schouteni . The two families of carnivorous marsupials likely did not compete with each other due to differences in both body size and vertical habitat segregation. [11] Both species of Wabulacinus show adaptation towards hypercarnivory, such as the reduction of tooth complexity and elongation of the shearing crests. In addition, the relatively broad snout of W. ridei would have allowed it to chew more efficiently and to deliver a more powerful bite. [6]
The order Peramelemorphia includes the bandicoots and bilbies. All members of the order are endemic to Australia-New Guinea and most have the characteristic bandicoot shape: a plump, arch-backed body with a long, delicately tapering snout, very large upright ears, relatively long, thin legs, and a thin tail. Their size varies from about 140 grams up to 4 kilograms, but most species are about one kilogram.
Thylacinidae is an extinct family of carnivorous marsupials from the order Dasyuromorphia. The only species to survive into modern times was the thylacine, which became extinct in 1936.
Thylacinus is a genus of extinct carnivorous marsupials in the family Thylacinidae. The only recent member was the thylacine, commonly also known as the Tasmanian tiger or Tasmanian wolf. The last known Tasmanian tiger was in the Beaumaris Zoo in Tasmania, eventually dying in 1936. The earliest known member of the genus, Thylacinus macknessi appeared during the Early Miocene, around 16 million years ago, and was smaller than the modern thylacine, with a body mass of about 6.7–9.0 kilograms (14.8–19.8 lb). Thylacinus represented the only extant genus of the family after the beginning of the Pliocene around 5 million years ago. Over time members of the genus saw an increase in body mass and a greater adaption to hypercarnivory in their dental morphology.
Badjcinus is an extinct thylacinid marsupial. It is the earliest and most primitive known thylacinid, living 23 to 28 million years ago in the late Oligocene.
Wakaleo is an extinct genus of medium-sized thylacoleonids that lived in Australia in the Late Oligocene and Miocene Epochs.
Yarala is a genus of fossil mammals that resemble contemporary bandicoots. The superfamily Yaraloidea and family Yaralidae were created following the discovery of the type species Yarala burchfieldi in 1995, on the basis that it lacks synapomorphies that unite all other peramelemorphian taxa.
The genus Nimbacinus contains two species of carnivorous, quadrupedal marsupials in Australia both of which are extinct:
Neohelos is an extinct diprotodontid marsupial, that lived from the early to middle-Miocene. There are four species assigned to this genus, Neohelos tirarensis, the type species, N. stirtoni, N. solus and N. davidridei. N. davidridei is the most derived species of the genus, and its premolar morphology shows that it is structurally and ancestor of the genus Kolopsis. All four species are from the Bullock Creek in the Northern Territory and Riversleigh of Australia.
Thylacinus macknessi lived during the early Miocene and is the oldest known member of the genus Thylacinus. It is named after Brian Mackness, a supporter of Australian vertebrate paleontology.
Thylacinus megiriani lived during the late Miocene, 8 million years ago; the area T. megiriani inhabited in the Northern Territory was covered in forest with a permanent supply of water.
Maximucinus is an extinct genus of thylacinid that lived during the Middle Miocene in what is now Queensland, Australia. It is known only a second upper molar found at the Riversleigh World Heritage Area. It was the largest thylacinid of its time, attaining a body size of 18 kg. The genus is monotypic, containing only one species, Maximucinus muirheadae.
Muribacinus is an extinct genus of thylacinid that lived during the middle Miocene in what is now northwestern Queensland, Australia. It was described in 1995 from remains collected at the Riversleigh World Heritage Area. Only one species is known, M. gadiyuli.
Mutpuracinus archibaldi is an extinct carnivorous, quadrupedal marsupial that lived during the middle Miocene and is the smallest known thylacinid at approximately 1.1 kilograms, the size of a quoll, though, more closely related to the recently extinct thylacine.
Ngamalacinus is an extinct genus of thylacinid marsupial that lived during the late Oligocene and early Miocene of Australia. Fossils have been found in Riversleigh.
Tyarrpecinus is an extinct genus of thylacinid that lived during the late Miocene in what is now the Northern Territory, Australia. It is known only from a partial skull bone that was reconstructed from numerous fragments. It was a small thylacinid and represents a late surviving relict. The genus is monotypic, containing only one species, Tyarrpecinus rothi.
The Macropodidae are an extant family of marsupial with the distinction of the ability to move bipedally on the hind legs, sometimes by jumping, as well as quadrupedally. They are herbivores, but some fossil genera like Ekaltadeta are hypothesised to have been carnivores. The taxonomic affiliations within the family and with other groups of marsupials is still in flux.
Propalorchestes is a fossil genus of palorchestid marsupial that existed in Australia during the Miocene epoch.
Lekaneleo is a fossil genus of carnivorous marsupial that existed during the early Miocene in Australia. Once allied to the type species of the genus Priscileo, later placed as Wakaleo pitikantensis, "Priscileo" roskellyae was subsequently transferred to its own genus Lekaneleo.
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William D. Turnbull (1922-2011) was an American paleontologist associated with the Chicago Field Museum. He published over 100 papers on mammals, continuing after his retirement as the museum's curator of mammals. He searched in Australia for evidence of recently extinct species, and made frequent expeditions to sites at the Washakie Formation in southwest Wyoming. His studies are considered significant contributions to the paleontology and biogeography of dinosaurs and Eocene mammals.