Draft edit
Species edit
The new genus was rationalised because of its distinctive maxilla (upper jawbone) and the proportions of its snout.[1] Preliminary comparisons were made with sebecosuchians, pristichampsines, and modern crocodylids.[2] The definition of Q. fortirostrum compared the maxilla to crocodilians and determined that the specimen exhibited substantial palatine (upper mouth bone) and alveoli (tooth sockets) differences to be considered a new genus.[1] The palatine exhibited a shorter jugal (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 Crocodylidae. The speciation was supported with multiple Pleistocene examples of maxilla and teeth found throughout Queensland and northern New South Wales.[1]
- Quinkana timara
A second species named Quinkana timara was described by paleontologist Dirk Megirian in 1994.[3] The holotype (NTM P895-19 from the Northern Territory Museum) consisted of premaxilla (foremost upper jawbone), maxilla, and jugal fragments within limestone 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 Miocene.[4] The collected specimens were compared with Q. fortirostrum and Pristichampsus species. Q. timara was attributed to Quinkana because it shared the same ziphodont teeth orientation and snout formation as Q. fortirostrum.[3] The species was defined as having a “narrower snout” and “proportionally larger antorbital shelf [opening in the skull]” than Q. fortirostrum. This distinction is reflected in the name timara, which are thin Quinkans or “spirits" in Gugu-Yalanji mythology.[3]
- 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 northeast Queensland.[5] Other referred specimens including teeth were found in the same location and were estimated to be early Pliocene in age.[6] Q. babarra was determined to have an abbreviated and wider shout compared to Q. foritrostrum and Q. timara.[5] 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.[5]
- 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.[7] The specimens were found at the White Hunter Site in northwestern Queensland which is a late Oligocene deposit. The species has a narrower snout than Q. fortirostrum and a low alveolar ridge. The species is named for Ulrich Mebold, a German astronomer.[7]
- 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 northwestern Queensland.[8] Although it exhibited alveolar similarities with Quinkana, the maxilla 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.[5]
A late Pleistocene tooth (QM F57032) was found in 2013 in the King Creek site of southeastern Queensland and attributed to Quinkana. It was most similar to framentary teeth from Q. foritrostrum, but was not attributed to any species because of a lack of complete specimens.[9]
Paleobiology edit
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.[8] 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.[10][11] The issue remains contested due to a lack of evidence.
It was proposed in 1981 that the species may have been a dominant predator because there were no other known terrestrial hunters in the Tertiary and Pleistocene periods.[8] It was also suggested that Quinkana’s ziphodont teeth indicated, “predation upon larger prey than is usual for crocodiles”.[8] 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.[5][11]
Phylogeny edit
Q. fortirostrum was originally classified under Crocodylidae in 1981 through comparison against other Crocodilia genuses Pristichampsus, Paleosuchus, and Osteolaemus and against Sebecosuchia genus Sebecus.[8] 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 genuses shared those features. These discrepancies led to the attribution of Q. fortirostrum to Crocodylidae with the acknowledgement of this potential ambiguity.
The subfamily Mekosuchinae was proposed in 1993 by Molnar, Willis, and Professor John Scanlon to accurately define a growing number of Australian crocodilian genera.[12] It was designed to accommodate Quinkana and other genera which demonstrated unique dentary characteristics and were native to Australiasia during the Tertiary or Quarternary period. Quinkana remains an outlier because it is the only ziphodont genus within the subfamily.[5] The Mekosuchinae classification was contrasted in the 1994 speciation of Q. timara suggesting that further research into the phylogeny of Pristichampsus and Quinkana was necessary because of significant “structural similarities” in the snout when compared to other Crocodylidae.[3]
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Answers to Module 7 Questions edit
1. Describe your media.
I created a map displaying the locations of found fossil deposits of the Quinkana, a prehistoric crocodilian.
2. Is it your own work?
I used an existing map of Queensland with a CC-BY-SA license. This license allows adaptations to be created with appropriate credits to the original author. My additions of text, shading, and location points sufficiently altered the original work and will effectively support the final article.
3. What is the file format?
The file is a .PNG image.
4. What license have you chosen?
As it is a 'share alike' license, I am required to retain the original CC-BY-SA license.
5. What category/gallery will you add it to?
The map will be added to the 'Location Maps of Queensland' category.
6. How will you describe the file?
'Map of found Quinkana fortirostrum fossils in Queensland'
Practicing citations edit
The paper examines the causes of extinction for several species including the Quinkana.[13]
The physical characteristics will be referenced in the ‘Description’ heading and will also be used in the ‘Q. timara’ (‘Species’ section) subheading along with information about the discovery, specimens, and classification of the subspecies.[14]
This source can resolve the deficient references in the existing article’s ‘Lead Section’ and ‘Phylogeny’ for physical characteristics, naming entomology, and taxonomy.[15]
The article also discusses the role of the Quinkana in its ecosystem (as predacious, semi-aquatic) which will be referenced in the ‘Paleobiology’ section.[16]
The physical description, specimens, and classification of this subspecies will be referenced in its subheading (under ‘Species’ heading).[17]
References edit
- ^ a b c Molnar, R. E. (1977-07-01). "Crocodile with Laterally Compressed Snout: First Find in Australia". Science. 197 (4298): 62–64. doi:10.1126/science.197.4298.62. ISSN 0036-8075.
- ^ Archer, Michael (1978). "Quaternary vertebrate faunas from the Texas Caves of southeastern Queensland". Memoirs of the Queensland Museum. 19 (1): 61–109.
- ^ a b c d Megirian, Dirk (1994). "A New Species of Quinkana Molnar (Eusuchia: Crocodylidae) from the Miocene Camfield Beds of Northern Australia". The Beagle. 11: 145–166.
- ^ Murray, Peter; Megirian, Dirk (December 1992). "Continuity and Contrast in Middle and Late Miocene Vertebrate Communities from the Northern Territory". The Beagle. 9: 195–217.
- ^ a b c d e f Willis, Paul M.A.; Mackness, Brian S. (1996). "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". Proceedings of the Linnean Society of New South Wales. 116: 143–151.
- ^ Mackness, Brian S. (1995). "Palorchestes selestiae, a new species of palorchestid marsupial from the Early Pliocene Bluff Downs Local Fauna, northeastern Queensland". Memoirs of the Queensland Museum. 38 (1): 603–609.
- ^ a b Willis, Paul M.A. (1997). "New crocodilians from the late Oligocene White Hunter Site, Riversleigh, northwestern Queensland". Memoirs of the Queensland Museum. 41: 423–438.
- ^ a b c d e Molnar, R. E. (1981-10-31). "Pleistocene ziphodont crocodilians of Queensland". Records of the Australian Museum. 33 (19): 803–834. doi:10.3853/j.0067-1975.33.1981.198. ISSN 0067-1975.
- ^ Sobbe, Ian H.; Price, Gilbert J.; Knezour, Robert A. (2013). "A ziphodont crocodile from the late Pleistocene King Creek catchment, Darling Downs, Queensland". Memoirs of the Queensland Museum. 52 (2): 601–606.
- ^ Mackness, Brian S.; Sutton, Richard (2000). "Possible evidence for intraspecific aggression in a Pliocene crocodile from north Queensland". Alcheringa: An Australasian Journal of Palaeontology. 24 (1): 55–62. doi:10.1080/03115510008619523. ISSN 0311-5518.
- ^ a b Wroe, Stephen (2002). "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". Australian Journal of Zoology. 50 (1): 1. doi:10.1071/zo01053. ISSN 0004-959X.
- ^ Willis, Paul M.A.; Molnar, Ralph E.; Scanlon, John D. (1993). "An early Eocene crocodilian from Murgon, southeastern Queensland". Kaupia: Darmstädter Beiträge zur Naturgeschichte. 3: 27–33.
- ^ Hocknull, Scott A., Richard Lewis, Lee J. Arnold, Tim Pietsch, Joannes-Boyau Renaud, Gilbert J. Price, Patrick Moss, et al. "Extinction of Eastern Sahul Megafauna Coincides with Sustained Environmental Deterioration." Nature Communications vol. 11, no. 1 (2020).
- ^ Megirian, Dirk. “A New Species of Quinkana Molnar (Eusuchia: Crocodylidae) from the Miocene Camfield Beds of Northern Australia.” The Beagle vol. 11 (November 1994): 145–166.
- ^ Molnar, Ralph E. “Pleistocene ziphodont crocodilians of Queensland.” Records of the Australian Museum vol. 33, no. 19 (October 1981): 803–834.
- ^ Willis, Paul M.A. and Mackness, Brian S. “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.” Proceedings of the Linnean Society of New South Wales vol. 116, (1996): 143-151.
- ^ Wroe, Stephen. “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.” Australian Journal of Zoology vol. 50, no. 1 (2002): 1–24.