Post by dinosauria101 on Apr 24, 2019 16:51:16 GMT 5
Austroraptor cabazai
Life reconstruction of A. cabazai. © @ Frederic Wierum
Temporal range: Late Cretaceous; middle Campanian to early Maastrichtian[1][2][3]
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Clade: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Reptilia or Sauropsida
Clade: Eureptilia
Clade: Romeriida
Clade: Diapsida
Clade: Neodiapsida
Clade: Archelosauria
Clade: Archosauromorpha
Clade: Archosauriformes
Clade: Crurotarsi
Clade: Archosauria
Clade: Avemetatarsalia
Clade: Ornithodira
Clade: Dinosauromorpha
Clade: Dinosauriformes
Clade: Dinosauria
Order: Saurischia
Clade: Eusaurischia
Clade: Theropoda
Clade: Neotheropoda
Clade: Averostra
Clade: Tetanurae
Clade: Orionides
Clade: Avetheropoda
Clade: Coelurosauria
Clade: Tyrannoraptora
Clade: Maniraptoriformes
Clade: Maniraptora
Clade: Pennaraptora
Clade: Paraves
Clade: Eumaniraptora
Family: †Unenlagiidae[4]
Subfamily: †Unenlagiinae
Genus: †Austroraptor
Species: †A. cabazai
Austroraptor is a genus of theropod dinosaur belonging to the family Unenlagiidae. Its remains have been recovered from the Allen Formation of Argentina, which dates to the middle Campanian to early Maastrichtian ages[1][2][3]
Classification:
Unenlagiids have traditionally been thought of as a subfamily of the Dromaeosauridae. However, recent studies support separate family status for the unenlagiids, being closer to Avialae than to the dromaeosaurids.[4]
Description and biology:
Austroraptor was a rather large eumaniraptoran; the holotype specimen (MML 195) was estimated to be 5 meters long, with an extremely long and narrow 80 cm skull.[1] A second specimen described in 2013 (MML 220) was a slightly smaller adult individual.[2] Gregory S. Paul estimated Austroraptor at 6 meters.[5] Weight estimates for Austroraptor seem to vary much more. Paul estimated Austroraptor at 300 kg[5], while two other studies (coauthored by Roger B.J. Benson) have estimated Austroraptor to weigh 519-600 kg.[6][7]
The forelimbs of Austroraptor are notably reduced relative to size. This condition differs from what is seen in smaller unenlagiids such as Rahonavis and Buitreraptor.[1] The shortness of the forelimbs has led paleontologists to believe that the forelimbs of Austoraptor were not used to manipulate prey in the same way as smaller unenlagiids (like Buitreraptor), if at all.[8] Manual unguals are known; the ungual of D-1 is the strongest and deepest proximally, the D-2 ungual is only slightly more gracile, and the D-3 ungual is much more lightly built in comparison (although strongly curved, much more so than in dromaeosaurids). All claws have well-developed flexor tubercles.[2]
Mounted skeleton of A. cabazai at the Royal Ontario Museum. Note the elongated skull and short forelimbs. Image source.
Unenlagiids would have had better cursorial capabilities than dromaeosaurids, with the long and slender subarctometatarsus and less pronounced hinge joints of the metatarsals and phalanges. However, these same adaptations also reduced foot grip strength in comparison to eudromaeosaurs. Also, the longer second phalanx of D-2 allowed unenlagiids to move this digit more quickly, a useful adaptation for hunting smaller and elusive prey. Unenlagiids like Buitreraptor might also have used their pedal claws in a similar fashion to seriemas and phorusrhacids.[8]
Also, Austoraptor and its kin have been proposed to have had piscivorous diets on account of their unserrated teeth, similar to Microraptor. However, this alone is not evidence of a specialized piscivorous diet, and Microraptor itself also consumed animals other than fish.[8] Similarly, Greg Paul believes that while Austroraptor probably fished, predation on terrestrial animals is also plausible.[5]
Austroraptor is believed to have had a similar hunting method to its smaller relative Buitreraptor (with known remains suggesting good cursorial capabilities, as summarized above). However, Austroraptor would not have used its forelimbs in the same way Buitreraptor did, due to its proportionately shorter forelimbs. Additionally, Austroraptor’s teeth are conical, unlike the laterally compressed teeth of Buitreraptor, which likely made the former’s teeth more resistant to stress. This would therefore allow Austroraptor to seize and dismember large prey.[8]
References:
[1] Novas, F. E., Pol, D., Canale, J. I., Porfiri, J. D., & Calvo, J. O. (2009). A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids. Proceedings. Biological sciences, 276(1659), 1101–1107. doi.org/10.1098/rspb.2008.1554
[2] Currie, P. J., & Paulina Carabajal, A. (2013). A NEW SPECIMEN OF AUSTRORAPTOR CABAZAI NOVAS, POL, CANALE, PORFIRI AND CALVO, 2008 (DINOSAURIA, THEROPODA, UNENLAGIIDAE) FROM THE LATEST CRETACEOUS (MAASTRICHTIAN) OF RÍO NEGRO, ARGENTINA. Ameghiniana, 49(4), 662 - 667. Retrieved from www.ameghiniana.org.ar/index.php/ameghiniana/article/view/574
[3] Salgado, L., Coria, R., Ribeiro, C., Garrido, A., Rogers, R., Simón, M.E., Arcucci, A., Rogers, K.C., Carabajal, A.P., Apesteguía, S., Fernández, M., García, R.A., & Talevi, M. (2007). Upper Cretaceous dinosaur nesting sites of Río Negro (Salitral Ojo de Agua and Salinas de Trapalcó-Salitral de Santa Rosa), northern Patagonia, Argentina. Cretaceous Research, 28, 392-404.
[4] Motta, M. J., Agnolín, F. L., Brissón Egli, F., & Novas, F. E. (2020). New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana. Die Naturwissenschaften, 107(3), 24. doi.org/10.1007/s00114-020-01682-1
[5] Paul, G. S. (2016). The Princeton field guide to dinosaurs (Vol. 110). Princeton University Press. p. 151.
[6] Benson, R. B., Campione, N. E., Carrano, M. T., Mannion, P. D., Sullivan, C., Upchurch, P., & Evans, D. C. (2014). Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage. PLoS biology, 12(5), e1001853. doi.org/10.1371/journal.pbio.1001853
[7] Benson, R. B., Hunt, G., Carrano, M. T., & Campione, N. (2018). Cope’s rule and the adaptive landscape of dinosaur body size evolution. Palaeontology, 61(1), 13-48.
[8] Gianechini, F. A., Ercoli, M. D., & Díaz‐Martínez, I. (2020). [url=https://onlinelibrary.wiley.com/doi/pdf/10.1111/joa.13153?casa_token=LZBhrk0u3gIAAAAA:o3Dgdz27vFx7ajetzBFA9zFc7-eSVNScqd6Aoi8eeQwkFprEwSbqxBLldJ3AMMhUN2CRIOnHGoATITsDifferential locomotor and predatory strategies of Gondwanan and derived Laurasian dromaeosaurids (Dinosauria, Theropoda, Paraves): Inferences from morphometric and comparative anatomical studies[/url]. Journal of anatomy, 236(5), 772-797.
Life reconstruction of A. cabazai. © @ Frederic Wierum
Temporal range: Late Cretaceous; middle Campanian to early Maastrichtian[1][2][3]
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Clade: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Reptilia or Sauropsida
Clade: Eureptilia
Clade: Romeriida
Clade: Diapsida
Clade: Neodiapsida
Clade: Archelosauria
Clade: Archosauromorpha
Clade: Archosauriformes
Clade: Crurotarsi
Clade: Archosauria
Clade: Avemetatarsalia
Clade: Ornithodira
Clade: Dinosauromorpha
Clade: Dinosauriformes
Clade: Dinosauria
Order: Saurischia
Clade: Eusaurischia
Clade: Theropoda
Clade: Neotheropoda
Clade: Averostra
Clade: Tetanurae
Clade: Orionides
Clade: Avetheropoda
Clade: Coelurosauria
Clade: Tyrannoraptora
Clade: Maniraptoriformes
Clade: Maniraptora
Clade: Pennaraptora
Clade: Paraves
Clade: Eumaniraptora
Family: †Unenlagiidae[4]
Subfamily: †Unenlagiinae
Genus: †Austroraptor
Species: †A. cabazai
Austroraptor is a genus of theropod dinosaur belonging to the family Unenlagiidae. Its remains have been recovered from the Allen Formation of Argentina, which dates to the middle Campanian to early Maastrichtian ages[1][2][3]
Classification:
Unenlagiids have traditionally been thought of as a subfamily of the Dromaeosauridae. However, recent studies support separate family status for the unenlagiids, being closer to Avialae than to the dromaeosaurids.[4]
Description and biology:
Austroraptor was a rather large eumaniraptoran; the holotype specimen (MML 195) was estimated to be 5 meters long, with an extremely long and narrow 80 cm skull.[1] A second specimen described in 2013 (MML 220) was a slightly smaller adult individual.[2] Gregory S. Paul estimated Austroraptor at 6 meters.[5] Weight estimates for Austroraptor seem to vary much more. Paul estimated Austroraptor at 300 kg[5], while two other studies (coauthored by Roger B.J. Benson) have estimated Austroraptor to weigh 519-600 kg.[6][7]
The forelimbs of Austroraptor are notably reduced relative to size. This condition differs from what is seen in smaller unenlagiids such as Rahonavis and Buitreraptor.[1] The shortness of the forelimbs has led paleontologists to believe that the forelimbs of Austoraptor were not used to manipulate prey in the same way as smaller unenlagiids (like Buitreraptor), if at all.[8] Manual unguals are known; the ungual of D-1 is the strongest and deepest proximally, the D-2 ungual is only slightly more gracile, and the D-3 ungual is much more lightly built in comparison (although strongly curved, much more so than in dromaeosaurids). All claws have well-developed flexor tubercles.[2]
Mounted skeleton of A. cabazai at the Royal Ontario Museum. Note the elongated skull and short forelimbs. Image source.
Unenlagiids would have had better cursorial capabilities than dromaeosaurids, with the long and slender subarctometatarsus and less pronounced hinge joints of the metatarsals and phalanges. However, these same adaptations also reduced foot grip strength in comparison to eudromaeosaurs. Also, the longer second phalanx of D-2 allowed unenlagiids to move this digit more quickly, a useful adaptation for hunting smaller and elusive prey. Unenlagiids like Buitreraptor might also have used their pedal claws in a similar fashion to seriemas and phorusrhacids.[8]
Also, Austoraptor and its kin have been proposed to have had piscivorous diets on account of their unserrated teeth, similar to Microraptor. However, this alone is not evidence of a specialized piscivorous diet, and Microraptor itself also consumed animals other than fish.[8] Similarly, Greg Paul believes that while Austroraptor probably fished, predation on terrestrial animals is also plausible.[5]
Austroraptor is believed to have had a similar hunting method to its smaller relative Buitreraptor (with known remains suggesting good cursorial capabilities, as summarized above). However, Austroraptor would not have used its forelimbs in the same way Buitreraptor did, due to its proportionately shorter forelimbs. Additionally, Austroraptor’s teeth are conical, unlike the laterally compressed teeth of Buitreraptor, which likely made the former’s teeth more resistant to stress. This would therefore allow Austroraptor to seize and dismember large prey.[8]
References:
[1] Novas, F. E., Pol, D., Canale, J. I., Porfiri, J. D., & Calvo, J. O. (2009). A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids. Proceedings. Biological sciences, 276(1659), 1101–1107. doi.org/10.1098/rspb.2008.1554
[2] Currie, P. J., & Paulina Carabajal, A. (2013). A NEW SPECIMEN OF AUSTRORAPTOR CABAZAI NOVAS, POL, CANALE, PORFIRI AND CALVO, 2008 (DINOSAURIA, THEROPODA, UNENLAGIIDAE) FROM THE LATEST CRETACEOUS (MAASTRICHTIAN) OF RÍO NEGRO, ARGENTINA. Ameghiniana, 49(4), 662 - 667. Retrieved from www.ameghiniana.org.ar/index.php/ameghiniana/article/view/574
[3] Salgado, L., Coria, R., Ribeiro, C., Garrido, A., Rogers, R., Simón, M.E., Arcucci, A., Rogers, K.C., Carabajal, A.P., Apesteguía, S., Fernández, M., García, R.A., & Talevi, M. (2007). Upper Cretaceous dinosaur nesting sites of Río Negro (Salitral Ojo de Agua and Salinas de Trapalcó-Salitral de Santa Rosa), northern Patagonia, Argentina. Cretaceous Research, 28, 392-404.
[4] Motta, M. J., Agnolín, F. L., Brissón Egli, F., & Novas, F. E. (2020). New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana. Die Naturwissenschaften, 107(3), 24. doi.org/10.1007/s00114-020-01682-1
[5] Paul, G. S. (2016). The Princeton field guide to dinosaurs (Vol. 110). Princeton University Press. p. 151.
[6] Benson, R. B., Campione, N. E., Carrano, M. T., Mannion, P. D., Sullivan, C., Upchurch, P., & Evans, D. C. (2014). Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage. PLoS biology, 12(5), e1001853. doi.org/10.1371/journal.pbio.1001853
[7] Benson, R. B., Hunt, G., Carrano, M. T., & Campione, N. (2018). Cope’s rule and the adaptive landscape of dinosaur body size evolution. Palaeontology, 61(1), 13-48.
[8] Gianechini, F. A., Ercoli, M. D., & Díaz‐Martínez, I. (2020). [url=https://onlinelibrary.wiley.com/doi/pdf/10.1111/joa.13153?casa_token=LZBhrk0u3gIAAAAA:o3Dgdz27vFx7ajetzBFA9zFc7-eSVNScqd6Aoi8eeQwkFprEwSbqxBLldJ3AMMhUN2CRIOnHGoATITsDifferential locomotor and predatory strategies of Gondwanan and derived Laurasian dromaeosaurids (Dinosauria, Theropoda, Paraves): Inferences from morphometric and comparative anatomical studies[/url]. Journal of anatomy, 236(5), 772-797.
