Quinkana

Quinkana
	Skull reconstruction of Quinkana timara
Temporal occurrence
	Oligocene to Pleistocene
Locations
	Queensland , Northern Territory ( Australia );
Systematics
	Eusuchia
	Crocodiles (crocodylia)
	Crocodyloidea
	Real crocodiles (Crocodylidae)
	Mekosuchinae
	Quinkana
Scientific name
	Quinkana
	Molnar , 1981
species
	Quinkana babarra Willis & Mackness, 1996 ; Quinkana fortirostrum Molnar, 1981 ( type species ) ; Quinkana meboldi Willis, 1997 ; Quinkana timara Megirian, 1994 ;

Quinkana is an extinct genus of possibly terrestrial crocodiles from the group of Mekosuchinae . The genus can be identified with several species from the late Oligocene to the late Pleistocene of Australia .

Etymology and history of research

The generic name Quinkana is derived from "Quinkan". The term probably comes from the language of Gugu-Yalanji and refers to a spirit being from the mythology of the Aborigines . "Quinkans" were depicted in at least one case from the Cape York Peninsula in rock paintings in connection with crocodiles.

The remains of ziphodont crocodiles from the Pliocene and Pleistocene of New Guinea and Australia were known as early as the 1960s and 1970s . The finds were important in that ziphodontal crocodiles became extinct elsewhere by the end of the Miocene at the latest.

The first description of the genus and its type Quinkana fortirostrum was made in 1981 by the Australian paleontologist Ralph Molnar . The additional species " fortirostrum " (from Latin " fortis ": "strong", "strong" and " rostrum ": "beak", used here in the sense of "snout") refers to the relatively wide and high snout of the holotype from the Pleistocene of Queensland .

In 1994 Dirk Megirian described a second species of the genus, Quinkana timara , from the Miocene of the Northern Territory . The additional species " timara " is also borrowed from the mythology of the Gugu-Yalanji. The name "Timara" means a "slim Quinkan" in their language. With Quinkana babarra from the Pliocene of Queensland, the third species followed in 1996. As a species addition a word from the Gugu-Yalanji language was chosen by the first descriptions. The term " babarr " can be translated as "older sister" and refers to the higher age of the species compared to Quinkana fortirostrum . Both species each required a revision of the generic diagnosis .

The fourth species, which was first described in 1997, Quinkana meboldi from the Upper Oligocene of Queensland, was included in the generic diagnosis of 1996 without further adjustment. This time, however, the new species was named after the radio astronomer Ulrich Mebold .

features

Isolated dental crown of Quinkana sp.

Quinkana is a genus of Mekosuchin crocodiles with a moderately high snout and blade-like, ziphodontic teeth. The alveoli are elongated and their longitudinal axis is aligned with the row of teeth or at a slight angle to it. The alveoli of the maxilla are all approximately the same size. The clearly pronounced alveolar process of the maxilla has pits medially to accommodate the tooth tips of the lower jaw.

The snout has an approximately trapezoidal outline in the area immediately in front of the eye sockets . The suture between maxilla and premaxilla is U-shaped in the palate area and convex backwards. The festooning of the jaw margins is only weak. A forward-facing process of the palatine bone is only very short or missing entirely.

species

Quinkana fortirostrum Molnar , 1981 (Pleistocene; type species)

In addition to the genus-typical characteristics, Q. fortirostrum is characterized by an orbital edge lying in front of or just above the edge of the palatal window and three bony cusps on the tearbone and the pre-frontal bone dorsal to the anterior edge of the eye sockets. The anterior margins of the palatal windows extend to the seventh tooth of the maxilla. The cutting edges of the teeth are always serrated. For Q. fortirostrum a length of 3 m with a body mass of 200 kg is usually given. However, it seems unclear how these measurements were determined and at least the information on body mass is viewed by some authors as unrealistically high.

Quinkana babarra Willis & Mackness , 1996 (Pliocene)

Quinkana babarra differs from Q. fortirostrum and Q. timara by its shorter and wider snout and a weakly indicated festooning, which is not shown at all in the other two species. The anterior margins of the palatal window extend to the fifth and sixth teeth of the maxilla. The teeth themselves show both serrated and smooth cutting edges. The holotype of Q. babarra is slightly smaller than that of Q. fortirostrum and Q. timara . A lower jaw fragment from the same locality, which can possibly be assigned to Q. babarra , suggests, however, that the species could reach a length of up to 6-7 m.

Quinkana timara Megirian , 1994 (Miocene)

Quinkana timara has a much narrower snout compared to Q. fortirostrum . The anterior margins of the palatal window extend to the eighth tooth of the maxilla. The cutting edges of the teeth are always serrated.

Quinkana meboldi Willis , 1997 (Upper Oligocene)

The snout of Q. meboldi is narrower than that of Q. fortirostrum and the jaw margins show a weakly indicated festooning. The anterior margins of the palatal window extend to the eighth tooth of the maxilla. The cutting edges of the teeth are always smooth. A length of <1.5 m is estimated for Q. meboldi .

Paleecology

A terrestrial way of life is often assumed for Quinkana . The finding is, however, controversial in the specialist literature. Molnar does not consider the question in his first description of genus and type species to be decidable, since neither fossil evidence nor the sedimentological features of the sites allow a clear statement. Like Molnar, Megirian also points to similarities with the genera Pristichampsus (= Boverisuchus sensu Brochu , 2013) from the Eocene of Europe and Sebecus from the Eocene of South America. In particular, he cites some features of the cranial skeleton (ziphodontic teeth; relatively narrow, high-backed snout; rather laterally rather than forward-facing eye sockets) as indications of a terrestrial way of life for Quinkana .

Especially in popular science works and occasionally also in the non paleontological oriented literature are sometimes hufartig deformed claws and a more rounded in cross-section, rather than laterally flattened tail cited as evidence of terrestrial life. However, there is no direct fossil evidence for this , as no postcranial skeletal elements are known for Quinkana . This information is based solely on the comparison with the genus Boverisuchus , for which these characteristics have been described. Quinkana (Mekosuchinae) and Boverisuchus ( Planocraniidae ) are not closely related to each other and belong to different clades within the Eusuchia .

While some authors strongly question a purely terrestrial way of life for Quinkana , others see the similarities of skull shape and dentition between Quinkana and the Planocraniidae as an indication of a convergent development and see in Quinkana, besides the Planocraniidae, a second, independent return of the crocodiles to a terrestrial one Way of life.

literature

Patricia Vickers-Rich , Gerard F. van Tets : Kadimakara, Extinct Vertebrates of Australia. Princeton University Press, Princeton NJ 1990, ISBN 0-691-08733-4 .
Ralph E. Molnar: Dragons in the dust. The paleobiology of the giant monitor lizard Megalania . Indiana University Press, Bloomington IN 2004, ISBN 0-253-34374-7 .
Danielle Clode: Prehistoric Giants. The Megafauna of Australia. Victoria Museum, Carlton Vic. 2009, ISBN 978-0-9803813-2-0 .

Individual evidence

^ ^A ^b ^c P. MA Willis: New crocodilians from the late Oligocenc White Hunter Site, Riversleigh, northwestern Queensland. In: Memoirs of the Queensland Museum , Volume 41, Number 2, 1997, pp. 423-438, ( digitized ).
^ IH Sobbe, GJ Price & RA Knezour: A ziphodont crocodile from the late Pleistocene King Creek catchment, Queensland. In: Memoirs of the Queensland Museum - Nature , Volume 56, Number 2, 2013, pp. 601-606, ( digitized ).
↑ ^a ^b ^c ^d ^e R. E. Molnar: Pleistocene Ziphodont Crocodilians of Queensland. In: Records of The Australian Museum , Volume 33, Number 19, 1981, pp. 803-834, ( digitized ).
↑ ^a ^b ^c D. Megirian: A new Species of Quinkana MOLNAR (Eusuchia: Crocodylidae) from the Miocene Camfield Beds of Northern Australia. In: The Beagle, Records of the Museums and Art Galleries of the Northern Territory , Volume 11, 1994, pp. 145-166, ( digitized ).
↑ ^a ^b ^c ^d ^e ^f ^g ^h P. MA Willis & BS Mackness: Quinkana babarra, a New Species of Ziphodont Mekosuchine Crocodile from the Early Pliocene Bluff Downs Local Fauna, Northern Australia with a Revision of the Genus. In: Proceedings of the Linnean Society of New South Wales , Volume 116, 1996, pp. 143-151, ( digitized ).
↑ ^a ^b ^c ^d S. Wroe: A review of terrestrial mammalian and reptilian carnivore ecology in Australian fossil faunas, and factors influencing their diversity: the myth of reptilian domination and its broader ramifications. In: Australian Journal of Zoology , Volume 50, 2002, pp. 1-24, ( digitized ).
↑ JD Scanlon: Giant terrestrial reptilian carnivores of Cenozoic Australia. In: A. Glen & Ch. Dickman (Eds.): Carnivores of Australia: Past, Present and Future. CSIRO Publishing, 2014, ISBN 978-0643103108 , p. 30, ( digitized version ).

^ ^A ^b Ch. A. Brochu: Phylogenetic relationships of Palaeogene ziphodont eusuchians and the status of Pristichampsus Gervais, 1853. In: Earth and Environmental Science Transactions of the Royal Society of Edinburgh , Volume 103, 2013, pp. 521-550, ( Digitized ).

^ C. Tudge: The Time Before History. Simon & Schuster, New York, 1996, ISBN 0-684-80726-2 , p. 87, ( reading sample ).

^ LJ Vitt & JP Caldwell: Herpetology: An Introductory Biology of Amphibians and Reptiles. 4th edition, Elsevier, Amsterdam / Boston / Heidelberg / London / New York / Oxford / Paris / San Diego / San Francisco / Sydney / Tokyo, 2014, ISBN 978-0-12-386919-7 , p. 105 ( reading sample ) .

^ EW Wilberg, AH Turner & Ch. A. Brochu: Evolutionary structure and timing of major habitat shifts in Crocodylomorpha. In: nature - Scientific Reports , Volume 9, 2019, 10 pages, doi : 10.1038 / s41598-018-36795-1 .

[Willis,_1997-1] A ^b ^c P. MA Willis: New crocodilians from the late Oligocenc White Hunter Site, Riversleigh, northwestern Queensland. In: Memoirs of the Queensland Museum , Volume 41, Number 2, 1997, pp. 423-438, ( digitized ).

[Sobbe_et_al.,_2013-2] IH Sobbe, GJ Price & RA Knezour: A ziphodont crocodile from the late Pleistocene King Creek catchment, Queensland. In: Memoirs of the Queensland Museum - Nature , Volume 56, Number 2, 2013, pp. 601-606, ( digitized ).

[Molnar,_1981-3] R. E. Molnar: Pleistocene Ziphodont Crocodilians of Queensland. In: Records of The Australian Museum , Volume 33, Number 19, 1981, pp. 803-834, ( digitized ).

[Megirian,_1994-4] D. Megirian: A new Species of Quinkana MOLNAR (Eusuchia: Crocodylidae) from the Miocene Camfield Beds of Northern Australia. In: The Beagle, Records of the Museums and Art Galleries of the Northern Territory , Volume 11, 1994, pp. 145-166, ( digitized ).

[Willis_&_Mackness,_1996-5] ↑ ^a ^b ^c ^d ^e ^f ^g ^h P. MA Willis & BS Mackness: Quinkana babarra, a New Species of Ziphodont Mekosuchine Crocodile from the Early Pliocene Bluff Downs Local Fauna, Northern Australia with a Revision of the Genus. In: Proceedings of the Linnean Society of New South Wales , Volume 116, 1996, pp. 143-151, ( digitized ).

[Wroe,_2002-6] S. Wroe: A review of terrestrial mammalian and reptilian carnivore ecology in Australian fossil faunas, and factors influencing their diversity: the myth of reptilian domination and its broader ramifications. In: Australian Journal of Zoology , Volume 50, 2002, pp. 1-24, ( digitized ).

[Scanlon,_2014-7] JD Scanlon: Giant terrestrial reptilian carnivores of Cenozoic Australia. In: A. Glen & Ch. Dickman (Eds.): Carnivores of Australia: Past, Present and Future. CSIRO Publishing, 2014, ISBN 978-0643103108 , p. 30, ( digitized version ).

[Brochu,_2013-8] A ^b Ch. A. Brochu: Phylogenetic relationships of Palaeogene ziphodont eusuchians and the status of Pristichampsus Gervais, 1853. In: Earth and Environmental Science Transactions of the Royal Society of Edinburgh , Volume 103, 2013, pp. 521-550, ( Digitized ).

[Tudge,_1996-9] C. Tudge: The Time Before History. Simon & Schuster, New York, 1996, ISBN 0-684-80726-2 , p. 87, ( reading sample ).

[Vitt_&_Caldwell,_2014-10] LJ Vitt & JP Caldwell: Herpetology: An Introductory Biology of Amphibians and Reptiles. 4th edition, Elsevier, Amsterdam / Boston / Heidelberg / London / New York / Oxford / Paris / San Diego / San Francisco / Sydney / Tokyo, 2014, ISBN 978-0-12-386919-7 , p. 105 ( reading sample ) .

[Wilberg_et_al,_2019-11] EW Wilberg, AH Turner & Ch. A. Brochu: Evolutionary structure and timing of major habitat shifts in Crocodylomorpha. In: nature - Scientific Reports , Volume 9, 2019, 10 pages, doi : 10.1038 / s41598-018-36795-1 .