''Quinkana'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of mekosuchine crocodylians that lived in

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

from about 28 million to about 10,000 years ago. Most attributed specimens have been found in

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

. It is speculated to have been one of the

top predators An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic le ...

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

Australia, along with megalania, the giant monitor lizard, and the modern

saltwater crocodile The saltwater crocodile (''Crocodylus porosus'') is a crocodilian native to saltwater habitats and brackish wetlands from India's east coast across Southeast Asia and the Sundaic region to northern Australia and Micronesia. It has been l ...

. The genus and type species, ''Q. fortirostrum'' was named by

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Ralph E. Molnar Ralph E. Molnar is a paleontologist who had been Curator of Mammals at the Queensland Museum and more recently associated with the Museum of Northern Arizona. He is also a research associate at the Texas natural Science Centre. He co-authored descr ...

in 1981. Other species in the genus are ''Q. timara'' (1994), ''Q. babarra'' (1996), and ''Q. meboldi'' (1997). The name ''Quinkana'' comes from the "Quinkans", a legendary folk spirit from Gugu-Yalanji mythology. ''Quinkana'' is thought to possess long legs and had ziphodont teeth (lateromedially compressed, recurved, and serrated). The genus is distinguishable by the combination of these ziphodont teeth and a broad

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is ...

. It also has a unique alveolar (tooth socket) structure and a short anterior palatine process (upper mouth bone). ''Quinkana'' was estimated to be around in length and to weigh around , with unnamed

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 However, these estimates are based on fragmentary specimens and dimensions of related genera as there have been no complete ''Quinkana'' specimens found. ''Quinkana'' was originally attributed to family

Crocodylidae Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant me ...

in 1981 without a further classification because of its unique physical characteristics. Some of its particular morphological traits shared by other Australian crocodile genera were entirely unique (primarily dentary and snout formations) which led to the creation of the subfamily

Mekosuchinae Mekosuchinae is an extinct clade of crocodilians from the Cenozoic of Australasia. They first appear in the fossil record in the Eocene in Australia, and survived until the arrival of humans: in the Pleistocene in Australia and within the Holocene ...

in 1993 to accommodate it. The genus has been argued amongst paleontologists to be entirely terrestrial or semi-aquatic with no definitive consensus. Academic analysis cites comparative morphologies as indicators of ''Quinkana''’s

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

ion to be terrestrial, but others argue that most specimens were discovered near known sources of water. An ongoing debate also persists about its dominance as a Pleistocene predator based upon the proportional quantity of predacious reptilian discoveries compared to predacious

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

ian predators. The opposing side questions its predominance through findings that it coexisted with several other predators and prey.

Species

The species within ''Quinkana'' include: the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

''Q. fortirostrum'' from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

,Sobbe, I. H.; Price, G. J.; Knezour, R. A. (2013
A ziphodont crocodile from the late Pleistocene King Creek catchment, Darling Downs, Queensland
Memoirs of the Queensland Museum – Nature, 56 2: 601-606. ''Q. babarra'' from the Early Pliocene of Queensland, ''Q. timara'' from the Middle

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

of the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

, and ''Q. meboldi'' from the Late

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

of Queensland. There also remains a number of unattributed specimens. ;''Quinkana fortirostrum'' ''Q. fortirostrum'' was discovered in the Chillagoe caves of Northern Queensland in 1970 by Lyndsey Hawkins, a member of the

Sydney University Speleological Society Sydney University Speleological Society (SUSS) is a caving group based in Sydney, Australia, which aims to unite University of Sydney graduates, undergraduates, staff and all other people who are interested in the exploration and mapping of ca ...

. The partial skull was described as of "unusual form" (

Australian Museum The Australian Museum is a heritage-listed museum at 1 William Street, Sydney central business district, New South Wales, Australia. It is the oldest museum in Australia,Design 5, 2016, p.1 and the fifth oldest natural history museum in the ...

F.57844). It was notable because of its higher snout orientation compared to extant crocodiles and the alveoli suggestion of ziphodont or laterally compressed teeth. The combination of these characteristics had previously not been found in Australia. Preliminary comparisons were made with

sebecosuchia Sebecosuchia is an extinct group of mesoeucrocodylian crocodyliforms that includes the families Sebecidae and Baurusuchidae. The group was long thought to have first appeared in the Late Cretaceous with the baurusuchids and become extinct in th ...

ns, pristichampsines, and modern crocodylids. Using this specimen, Ralph Molnar described ''Quinkana'' as a genus in 1981. Its generic name was derived from Quinkan, which is a term for “spirit” from the Northern Queensland aboriginal Gugu-Yalanji people. Quinkans were represented by crocodiles in at least one instance at a southeastern Cape York rock painting location. Molnar also created the type species ''Q. fortirostrum'', which was based on the Latin words fortis and rostrum meaning strong and beak (in reference to the species' snout). The new genus was rationalised because of its distinctive

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

(upper jawbone) and the proportions of its snout. Preliminary comparisons were made with sebecosuchians, pristichampsines, and modern crocodylids. The definition of ''Q. fortirostrum'' compared the maxilla to crocodilians and determined that the specimen exhibited substantial

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

(upper mouth bone) and

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * M ...

(tooth sockets) differences to be considered a new genus. The palatine exhibited a shorter

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

(cheek) and deeper infraorbital bar (bone between eye socket and palate) than what was common in crocodiles. The alveoli were found to be elongated which indicated that ''Q. fortirostrum'' had ziphodont or laterally compressed teeth, which differs from the interlocking teeth of ''

''. The speciation was supported with multiple

examples of maxilla and teeth found throughout

and northern

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. ;''Quinkana timara'' A second species named ''Quinkana timara'' was described by paleontologist Dirk Megirian in 1994. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

(NTM P895-19 from the

Northern Territory Museum Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a ...

) consisted of

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

(foremost upper jawbone), maxilla, and jugal fragments within

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

found in the Bullock Creek Locality in the Northern Territory. Additional referred specimens of maxilla fragments and teeth were found at the same site and were all determined to be from the middle to late

. The collected specimens were compared with ''Q. fortirostrum'' and ''

Pristichampsus ''Pristichampsus'' ("saw crocodile") is a non-diagnostic extinct genus of crocodylian from France and possibly also Kazakhstan that is part of the monotypic Pristichampsidae family. As the type species, ''Pristichampsus rollinatii'', was based o ...

'' species. ''Q. timara'' was attributed to ''Quinkana'' because it shared the same ziphodont teeth orientation and snout formation as ''Q. fortirostrum''. The species was defined as having a “narrower snout” and “proportionally larger antorbital shelf pening in the skull�� than ''Q. fortirostrum''. This distinction is reflected in the name ''timara'', which are thin Quinkans or “spirits" in Gugu-Yalanji mythology''. ;''Quinkana babarra'' The third species, ''Quinkana babarra'', was named in 1996 by researcher Brian Mackness and paleontologist Paul M.A. Willis. The holotype (QM F23220 from the Queensland Museum) was a maxilla fragment uncovered in 1991 by Mackness at the Dick’s Mother Lode Quarry in the Charters Towers Region northeast Queensland. Other referred specimens including teeth were found in the same location and were estimated to be early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 ''Q. babarra'' was determined to have an abbreviated and wider shout compared to ''Q. foritrostrum'' and ''Q. timara''. The new species also had a significant crest along its maxilla and premaxilla which was minimal in ''Q. timara'' and not present in ''Q. fortirostrum''. The name is derived from the Gugu-Yalanji word ''babarr'' meaning “older sister” in reference to ''Q. fortirostrum''. ;''Quinkana meboldi'' Three maxilla, two left (QM F31056 and QM F31057) and one right (QM F31058), and a partial dental specimen (QM F31059) were discovered by Willis in 1996. The specimens were found at the White Hunter Site in Riversleigh, northwestern Queensland which is a late

deposit. The species has a narrower snout than ''Q. fortirostrum'' and a low alveolar ridge. ''Q. meboldi'' is also thought to be smaller than other species at an estimated length of . The species was named in 1997 for Ulrich Mebold, a German astronomer. Quinkana tooth

;Unattributed specimens The speciation of ''Q. fortirostrum'' mentions a specimen consisting of a partial maxilla including two teeth (QM F10771) found at the Glen Garland Station in Yarraden, northwestern Queensland. Although it exhibited alveolar similarities with ''Quinkana'', the

was determined to be divergent from ''Q. fortirostrum'' and was therefore not attributed to the species. QM F10771 was later found to be similar to ''Q. barbarra'' in alveoli formation, but the palate of the specimen was too incomplete and it was recommended to remain unattributed. A late

tooth (QM F57032) was found in 2013 in the Kings Creek site of southeastern Queensland and attributed to ''Quinkana''. It was most similar to fragmentary teeth from ''Q. foritrostrum'', but was not attributed to any species because of a lack of complete specimens. A metatarsal bone (QM F30566) was found in 1992 in the Bluff Downs Fossil Site near

Allingham These notable people have the surname Allingham: * John Till Allingham (1776–1812), English dramatist. *William Allingham (1824 or 1828 – 1889), Irish man of letters and poet *Helen Allingham (née Helen Mary Elizabeth Paterson) (1848–1926), w ...

in north Queensland. It was thought to be Pliocene in age and was compared against ''Q. barbarra''. It represents a rare limb element which could be from ''Quinkana'', although no determination has been made of its species or genus.

Description

Most specimens of ''Quinkana'' were small in size, about , though, a fragmentary,

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58monitor lizard Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are rec ...

, '' Megalania''. One study argues that some species may have grown to , but this has been criticised for exaggeration despite having some academic support and being widely cited. It has been speculated to weigh around , although this estimate has also been criticised for being too large in comparison to related genera, extant

crocodile Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant me ...

s, and proportions of ''Quinkana''

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

specimens. The estimate is furthermore questioned because of a lack of complete ''Quinkana'' specimens. The genus is the only known

mekosuchinae Mekosuchinae is an extinct clade of crocodilians from the Cenozoic of Australasia. They first appear in the fossil record in the Eocene in Australia, and survived until the arrival of humans: in the Pleistocene in Australia and within the Holocene ...

with both a broad snout and ziphodont teeth. It can be distinguished primarily by its uniquely elongated and oriented

(tooth sockets) combined with a wide but short snout and a short anterior

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

process (upper mouth bone). ''Quinkana'' also have a U-shaped snout with a distinct

ry recess. Most species also share a similar pattern of crests along their snout, with dimensions varying by species. ''Quinkana'' has teeth which have

serration Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied p ...

s on some crowns but not on others. All of its teeth are mildly recurved similarly to extant crocodilians.

Taxonomy

''Quinkana'' is a genus within the subfamily

. Other genera included in this family are '' Australosuchus'', '' Baru'', '' Kambara'', ''

Mekosuchus ''Mekosuchus'' is a genus of extinct Australasian crocodiles within the subfamily Mekosuchinae. They are believed to have been made extinct by the arrival of humans on the South Pacific islands where they lived. The species of this genus were s ...

'', '' Paludirex'', and ''

Trilophosuchus ''Trilophosuchus'' ("Triple Crest Crocodile") is an extinct genus of mekosuchine crocodilian from Australia. Unlike living crocodilians, it is hypothesized to have been terrestrial. ''Trilophosuchus'' was approximately in length. It had a shor ...

''. The type species ''Q. fortirostrum'' was originally classified under

in 1981 through comparison against other

Crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest livi ...

genera ''

'', ''

Paleosuchus ''Paleosuchus'' is a South American genus of reptiles in the subfamily Caimaninae of the family Alligatoridae. They are the smallest members of the order Crocodilia in the Americas The Americas, which are sometimes collectively called ...

'', and ''

Osteolaemus ''Osteolaemus'' is a genus of crocodiles. They are small, secretive crocodiles that occur in wetlands of West and Middle Africa. They are commonly known as the African dwarf crocodiles. Unlike other crocodiles, ''Osteolaemus'' are strictly noctur ...

'' and against

Sebecosuchia Sebecosuchia is an extinct group of mesoeucrocodylian crocodyliforms that includes the families Sebecidae and Baurusuchidae. The group was long thought to have first appeared in the Late Cretaceous with the baurusuchids and become extinct in th ...

genus ''

Sebecus ''Sebecus'' (meaning "Sebek" in Latin) is an extinct genus of sebecid crocodylomorph from Eocene of South America. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by two species, the ...

''. The most similarities were found with ''Pristichampsus'' and it was determined that the genus should fall under Crocodilia. However, its ziphodont teeth and broad snout made it an outlier in the order as no other genera shared those features. These discrepancies led to the attribution of ''Q. fortirostrum'' to Crocodylidae with the acknowledgement of this potential ambiguity. The subfamily

was proposed in 1993 by Molnar, Willis, and Professor John Scanlon to accurately define a growing number of Australian crocodilian genera. It was designed to accommodate ''Quinkana'' and other genera which demonstrated unique dentary characteristics and were native to

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...

during the

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

period. ''Quinkana'' remains an outlier because it is the only ziphodont genus within the subfamily. The Mekosuchinae classification was contrasted in the 1994 speciation of ''Q. timara'' suggesting that further research into the

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological s ...

of ''Pristichampsus'' and ''Quinkana'' was necessary because of significant “structural similarities” in the snout when compared to other Crocodylidae. However, this has not altered the accepted classification and Mekosuchinae is the dominant phylogenic subfamily used in academic or research contexts. A 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. T ...

), and

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

(

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

age) data established the inter-relationships within Crocodylia. The

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

below shows the placement of ''Quinkana'' within

Paleobiology

''Quinkana'' was originally thought to be entirely terrestrial because many of the specimens had been found in caves and because other ziphodonts were known to be land-dwelling. Early analysis also discussed morphologic traits such as "hooflike

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

s" and a rounder as opposed to flattened

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

as indications of its terrestrial habitation. However, modern interpretations argued that it was semi-aquatic because all attributed specimens have been discovered in dig sites which were known to have been near bodies of water. The issue remains contested due to a lack of evidence. It has been suggested that ''Quinkana''’s ziphodont teeth indicated, “predation upon larger prey than is usual for

s”. Studies have also speculated that the genus’ ziphodont teeth indicate that it was a cursorial hunter as opposed to the ambush techniques utilised by extant

crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest livi ...

ns. This finding is also correlated with analysis of the pectoral and pelvic girdles of other

Mekosuchines Mekosuchinae is an extinct clade of crocodilians from the Cenozoic of Australasia. They first appear in the fossil record in the Eocene in Australia, and survived until the arrival of humans: in the Pleistocene in Australia and within the Holocen ...

which are theorised to be representative of ''Quinkana''’s anatomy, as no complete specimens have been found. It was proposed in 1981 that the species may have been a dominant

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...

because there were no other known terrestrial hunters in the

and

periods. Modern analysis has furthermore suggested that there was a " taxonomic-

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

shift" in Australia after the

, and beginning as early as the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

ian to reptilian. This theory of dominant reptilian predators including ''Quinkana'' and '' Megalania'' during the Tertiary and Pleistocene is supported by some academics, although others argue that these genera were not actively predacious because there is evidence that many reptilians and mammals coexisted. One study found ''Quinkana'' teeth in a Pleistocene river deposit in South Walker Creek in Western

amidst thirteen extinct and three extant genera, evenly split between

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

and

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

genera, with three genera of crocodilians, and suggested that this demonstrates a high level of coexistence. Analysis has also suggested that there may be possibilities for two or more predacious

ns to coexist in a singular

with the provision that they have distinct head shapes. In theory, this is thought to be because the distinct

morphologies indicate different types of

hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...

and use of habitats. This has been derived from modern analysis of

extant species Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, ''recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members sti ...

, but has generally correlated with other discoveries of overlapping carnivorous crocodilian deposits. One possible attributable ''Quinkana'' specimen presented evidence of a traumatic bite injury which would have occurred due to interspecies aggression. A study concluded that this was likely due to intraspecies aggression, but that it could also have been due to interspecies conflict. The causes for the species’

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...

in southeastern Queensland is considered to be environmental. With the presumption of ''Quinkana'' as a semi-aquatic predator, it has been suggested that the deterioration of river habitats in Queensland since the

Middle Pleistocene The Chibanian, widely known by its previous designation of Middle Pleistocene, is an age in the international geologic timescale or a stage in chronostratigraphy, being a division of the Pleistocene Epoch within the ongoing Quaternary Period. Th ...

led to its extinction. This is due to changes occurring from the last glacial cycle which created more open

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

s and resulted in more

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

s, which locally explains the extinction of water dependent species such as ''Quinkana''. Studies have also suggested that extant crocodilians managed to survive by moving to coastal habitats, while ''Quinkana'' did not.

References

{{Taxonbar, from=Q1934473, from2=Q112758227, from3=Q112758291, from4=Q112758362, from5=Q112758481 Mekosuchinae Oligocene crocodylomorphs Miocene crocodylomorphs Pliocene crocodylomorphs Pleistocene crocodylomorphs Pleistocene genus extinctions Pleistocene reptiles of Australia Crocodiles of Australia Apex predators Prehistoric pseudosuchian genera