Ngamalacinus Temporal range: Late Oligocene to Early Miocene | |
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Referred maxillary fragment of N. timmulvaneyi | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Infraclass: | Marsupialia |
Order: | Dasyuromorphia |
Family: | † Thylacinidae |
Genus: | † Ngamalacinus Muirhead, 1997 |
Type species | |
†Ngamalacinus timmulvaneyi Muirhead, 1997 | |
Other species | |
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Ngamalacinus is an extinct genus of thylacinid that lived in Australia from about 26 to 16 million years ago. Its fossils are solely known from the Riversleigh World Heritage Area in Queensland. Two species are currently known, the Early Miocene N. timmulvaneyi and the Late Oligocene N. nigelmarveni. In appearance it resembled a dog with a long snout. Its molar teeth were specialized for carnivory, the cups and crest were reduced or elongated to give the molars a cutting blade.
Ngamalacinus 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 N. timmulvaneyi (QM F16853) is a dentary fragment belonging to an immature individual. Additional remains, such as a maxilla and an isolated premolar, have also been referred to the species. All fossil material are a part of the paleontological collection at the Queensland Museum. [1]
In 2024, a new, older species of Ngamalacinus, N. nigelmarveni, was described from a broken left dentary. It hails from slightly earlier Riversleigh deposits. [2]
The generic name combines the Waanyi word "ngamala" (died out) and the Ancient Greek stem word "-kynos" (dog), alluding to its resemblance to the canid family. [1]
The skull of Ngamalacinus is poorly understood, with only a maxilla and two dentaries being known. The maxilla, represented by a fragment, retains most of the molars and premolars. Although not preserved, the upper canines were likely large given how deep its roots extend into the maxillary bone. A small gap (diastema) occurs between each premolar. Compared to other thylacinids, its teeth aren’t as long from front-to-back (anteroposteriorly). Stylar cusps B and D are small but distinct on the upper molars. In addition, the upper molar crests are angled at a narrow degree. Unlike Wabulacinus , the infraorbital foramen is positioned more towards the back of the maxilla. [1]
Only two dentaries are known, both of which are broken and preserve most of the molars. The coronoid process in both dentaries is angled at 120°. No gaps are present between each tooth. The teeth of N. nigelmarveni have a broad talonid and, on at least the fourth molar, trigonid basin. On all molars, the metaconid cusp has been reduced in size and is positioned more towards the back of the tooth. In addition, a distal ridge (known as a posterior cingulid) is present on all of the teeth. The fourth molar lacks an entoconid entirely, whilst also possessing a large hypoconulid. [1] [2]
N. timmulvaneyi was a fairly large thylacinid for its time, weighing up to 5.7-8.4 kg (12.6-18.5 lbs). [3] N. nigelmarveni, however, was considerably smaller, with an estimated body weight of 5.1 kg (11.2 lbs). [2]
In its initial description, the position of Ngamalacinus within Thylacinidae was tested by performing a single most parsimonious tree. The results of the tree found that it was sister taxon to the genera Wabulacinus and Thylacinus . [1] Subsequent studies, however, have attained conflicting results. Both Murray & Megirian (2000) and Yates (2015) found that it claded with Badjcinus as a sister group to all other thylacinids with the exception of Muribacinus . [4] [5] In at least two out of the three phylogenetic analyses performed by Rovinsky and colleagues (2019), Ngamalacinus claded with the Early-Middle Miocene taxa Muribaicnus and Nimbacinus . In the other analysis, it was found to be in a basal polytomy. [3]
In the description of Ngamalacinus nigelmarveni, three phylogenetic analyses were performed to test the relationships of the newly named species. Both the tip-and-node dated Bayesian analysis and strict consensus maximum parsimony showed support for its generic assignment and found the two species to be a part of a basal polytomy. The 50% majority rule consensus tree recovered similar results but differed in that instead of being within a polytomy it was sister group to one. [2]
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Ngamalacinus nigelmarveni is known exclusively from the Late Oligocene White Hunter site of Riversleigh, which has a date range of ~26-23 Ma. [2] During this period of time, Australia’s climate would have been cool and dry before shifting to a more warmer and wetter setting in the Early Miocene. [6] The environment inhabited by N. nigelmarveni consisted of open temperate forests or woodlands, with patches of rainforest growing around forest pools and watercourses. [7] [8] Plant fossils indicate the presence of deciduous vine thickets and sclerophyllous vegetation. [9] Living alongside N. nigelmarveni were the thylacinids Nimbacinus peterbridgei and Badjcinus turnbulli , and the thylacoleonids Wakaleo schouteni and Lekaneleo roskellyae . The two families of carnivorous marsupials likely did not compete with each other due to differences in both body size and vertical habitat segregation. [10] The teeth of N. nigelmarveni show adaptations towards hypercarnivory and were well equipped for longitudinal slicing. [2]
Fossils of N. timmulvaneyi are only known from two Early Miocene deposits, the Camel Sputum and Inabeyance sites. The Camel Sputum site has been radiometrically dated to ~18.5–17.0 Ma, while the age of the Inabeyance site is thought to have been ~18.5-16.2 Ma. [3] Both sites are interpreted as being open rainforest habitat. [7] Contemporaneous with N. timmulvaneyi was the similarly-sized, hypercarnivorous thylacinid Wabulacinus ridei . N. timmulvaneyi is thought to have been an unspecialised faunivore that fed on invertebrates and small vertebrates. [3]
Obdurodon is a genus of extinct platypus-like Australian monotreme which lived from the Late Oligocene to the Late Miocene. Three species have been described in the genus, the type species Obdurodon insignis, plus Obdurodon dicksoni and Obdurodon tharalkooschild. The species appeared much like their modern day relative the platypus, except adults retained their molar teeth, and unlike the platypus, which forages on the lakebed, they may have foraged in the water column or surface.
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.
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.
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.
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.
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.
Priscakoala is an extinct genus of koala from the Early Miocene of Riversleigh, Australia. It has one species: Priscakoala lucyturnbullae.
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.
Thylacinus yorkellus is a fossil species of carnivorous marsupial, a sister species of the recently extinct Thylacinus cynocephalus, the Tasmanian tiger, both of which existed on mainland Australia.
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.