Acheroraptor

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Acheroraptor
Temporal range: Late Cretaceous (Maastrichtian), 67.2–66  Ma
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Acheroraptor NMNH.jpg
Casts of the holotype maxilla and referred dentary, National Museum of Natural History.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Pennaraptora
Clade: Paraves
Family:† Dromaeosauridae
Genus:† Acheroraptor
Evans et al., 2013
Type species
†Acheroraptor temertyorum
Evans et al., 2013

Acheroraptor is an extinct genus of dromaeosaurid theropod dinosaur known from the latest Maastrichtian Hell Creek Formation of Montana, United States. It contains a single species, Acheroraptor temertyorum. A. temertyorum is one of the two geologically youngest known species of dromaeosaurids, the other being Dakotaraptor , which is also known from Hell Creek. A basal cousin of Velociraptor, Acheroraptor is known from upper and lower jaw material.

Contents

Discovery and naming

Known material Holotype ROM 63777.jpg
Known material

Acheroraptor was first described and named by David C. Evans, Derek W. Larson and Philip J. Currie in 2013 and the type species is Acheroraptor temertyorum. The generic name is derived from the Greek Ἀχέρων, Acheron, "underworld", in reference to the provenance from the Hell Creek Formation, and the Latin raptor, "thief". The specific name honours James and Louise Temerty, the chairman of Northland Power and the ROM Board of Governors and his wife, who have supported the museum for many years. [1]

Acheroraptor is known from the holotype ROM 63777, a complete right maxilla with several maxillary teeth (some isolated), and from a referred dentary (lower jaw) ROM 63778, both housed at the Royal Ontario Museum, Canada. Both specimens were collected approximately four metres from one another, from the same mixed faunal bonebed that occurs in the upper part of the Hell Creek Formation of Montana, dating to the latest Maastrichtian stage of the Late Cretaceous, immediately prior to the Cretaceous–Paleogene extinction event. The holotype specimen was collected on August 28, 2009, by commercial fossil hunters, one of whom also collected the dentary several years later, and who were later able to provide detailed geographic data from GPS and photographs of the specimen in situ in the ground on the day of discovery. Both specimens were subsequently purchased by the Royal Ontario Museum from a private collector. [1]

Classification

Restoration Acheroraptor reconstruction.jpg
Restoration

The phylogenetic position of Acheroraptor was explored by Evans et al. (2013) using several data matrices. Both specimens of Acheroraptor were coded as a single taxon into Turner et al. (2012) data matrix, an extensive phylogenetic analysis of theropods that focuses on maniraptorans. Acheroraptor was recovered as a member of the clade containing Eudromaeosauria and Microraptorinae, confirming its referral to the Dromaeosauridae, and possibly to Eudromaeosauria. Within that clade, however, most taxa were recovered in a large polytomy, due to the limited codings available for Acheroraptor. [1]

Evans et al. (2013) also coded the specimens of Acheroraptor (together and separately) into an updated version of the smaller, dromaeosaur-specific dataset from Longrich and Currie (2009). Velociraptor osmolskae and Balaur bondoc were added, Itemirus was excluded (following its identification as a tyrannosauroid by Miyashita and Currie (2009)), and following Turner et al. (2012) the codings for Adasaurus mongoliensis were separated into these based on the holotype from the Nemegt Formation, and these based on IGM 100/23 from the Bayanshiree Formation. Several characters were also rescored and modified, and two maxillary characters were added to the matrix from Turner et al. (2012). This analysis yielded a more resolved topology, placing Acheroraptor in a relatively basal position within the Velociraptorinae, which was otherwise found to include only Asian dromaeosaurids. The cladogram below shows the phylogenetic position of Acheroraptor following this analysis. [1]

Dromaeosauridae  

A 2022 study of eudromaeosauria reclassified Acheroraptor as a derived member of Saurornitholestinae, with Atrociraptor as its sister taxon. [2] Another study found support for Acheroraptor as a saurornitholestine, with Atrociraptor being recovered as its sister taxon again. [3]

Paleoecology

Acheroraptor and other fauna from Hell Creek (Acheroraptor in light orange) Hell Creek Formation Fauna.png
Acheroraptor and other fauna from Hell Creek (Acheroraptor in light orange)

Acheroraptor is the youngest species of dromaeosaurid, and is from the Hell Creek Formation. [1] The Hell Creek Formation is from the time of the Cretaceous-Paleogene Extinction Event, and has been dated to 66 ± 0.07 million years ago. [4] Many animals and plants have been found in the Hell Creek Formation, [5] the discovery site of Acheroraptor. As it is known from the Tyrannosaurus - Triceratops fauna, Acheroraptor is the youngest dromaeosaurid, along with the much larger Dakotaraptor . [1] [6]

Evans et al. found that Acheroraptor was the only dromaeosaurid from the Hell Creek Formation. Common teeth previously referred to Dromaeosaurus and Saurornitholestes would then be considered Acheroraptor. Evans et al. also concluded that there was probably only one dromaeosaurid in the Hell Creek-Lance assemblage. [1] In 2015, this view was disproven, with the description of Dakotaraptor , a far larger second dromaeosaur from the formation. [6] Other non-dromaeosaurid theropods from the formation are tyrannosaurids, ornithomimids, troodontids, [5] birds, [7] and caenagnathids. [8] The tyrannosaurids from the formation are Nanotyrannus and Tyrannosaurus, although the former might be a junior synonym of the latter. Among ornithomimids are the genera Struthiomimus as well as Ornithomimus , [5] and "Orcomimus." [9] The birds known from the formation are Avisaurus , [5] Brodavis baileyi, [10] and two unnamed hesperornithoforms, possibly Potamornis . [7] Only three oviraptorosaurs are from the Hell Creek Formation, Anzu , Leptorhynchos [8] and third and undescribed specimen, very similar to Gigantoraptor , from South Dakota. However, only fossilized foot prints were discovered as of 2016. [11] The known troodontids from this formation include Troodon , Pectinodon , and Paronychodon . A single species of coelurosaur is known from similar fossil formations includes Richardoestesia .

Life reconstruction of A. temertyorum Acheroraptor NT small.jpg
Life reconstruction of A. temertyorum

Ornithischians are abundant in the Hell Creek Formation. The main groups of ornithischians are ankylosaurians, ornithopods, ceratopsians, and pachycephalosaurians. One ankylosaurian and two nodosaurians are known, Ankylosaurus , Denversaurus and possibly Edmontonia . Multiple genera of ceratopsians are known from the formation, the leptoceratopsid Leptoceratops and the chasmosaurines Nedoceratops , Torosaurus , Triceratops, [5] and Tatankaceratops . [12] Hadrosaurs are common in the Hell Creek Formation, and are known from multiple species of the ornithopod Thescelosaurus , and the hadrosaurids Edmontosaurus , [5] [13] and an undescribed genus similar to Parasaurolophus . Five pachycephalosaurians have been found in the Hell Creek Formation. Among them are the derived pachycephalosaurids Sphaerotholus , Stygimoloch , [5] Dracorex , [14] Pachycephalosaurus , [5] and an undescribed specimen from North Dakota.

Mammals are plentiful in the Hell Creek Formation. Groups represented include multituberculates, metatherians, and eutherians. The multituberculates represented include Paracimexomys , [15] the cimolomyids Paressonodon , [16] Meniscoessus , Essonodon , Cimolomys , Cimolodon , and Cimexomys ; and the neoplagiaulacids Mesodma , and Neoplagiaulax . The alphadontids Alphadon , Protalphodon , and Turgidodon , pediomyids Pediomys , [15] Protolambda , and Leptalestes , [17] the stagodontid Didelphodon , [15] the deltatheridiid Nanocuris , the herpetotheriid Nortedelphys , [16] and the glasbiid Glasbius all represent metatherians of the Hell Creek Formation. A few eutherians are known, being represented by Alostera , [15] Protungulatum , [17] the cimolestids Cimolestes and Batodon , the gypsonictopsid Gypsonictops , and the possible nyctitheriid Paranyctoides . [15]

See also

Related Research Articles

<span class="mw-page-title-main">Dromaeosauridae</span> Family of theropod dinosaurs

Dromaeosauridae is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος (dromaîos), meaning 'running at full speed', 'swift', and σαῦρος (saûros), meaning 'lizard'. In informal usage, they are often called raptors, a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.

<i>Dromaeosaurus</i> Extinct genus of dinosaurs

Dromaeosaurus is a genus of dromaeosaurid theropod dinosaur that lived during the Late Cretaceous period, sometime between 80 and 69 million years ago, in Alberta, Canada and the western United States. The type species is Dromaeosaurus albertensis, which was described by William Diller Matthew and Barnum Brown in 1922. Its fossils were unearthed in the Hell Creek Formation, Horseshoe Canyon Formation and Dinosaur Park Formation. Teeth attributed to this genus have been found in the Prince Creek Formation. Dromaeosaurus is the type genus of both Dromaeosauridae and Dromaeosaurinae, which include many genera with similar characteristics to Dromaeosaurus such as possibly its closest relative Dakotaraptor. Dromaeosaurus was heavily built, more so than other dromaeosaurs that are similar in size, like Velociraptor.

<i>Saurornitholestes</i> Extinct genus of dinosaurs

Saurornitholestes is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States.

<i>Atrociraptor</i> Extinct genus of dinosaurs

Atrociraptor is a genus of saurornitholestine dromaeosaurid theropod dinosaur from the Late Cretaceous of Alberta, Canada.

<i>Bambiraptor</i> Extinct genus of dinosaurs

Bambiraptor is a Late Cretaceous, 72-million-year-old, bird-like dromaeosaurid theropod dinosaur described by scientists at the University of Kansas, Yale University, and the University of New Orleans.

<i>Achillobator</i> Extinct dromaeosaurid genus from the Late Cretaceous

Achillobator is a genus of large dromaeosaurid theropod dinosaur that lived during the Late Cretaceous period about 96 million to 89 million years ago in what is now the Bayan Shireh Formation of Mongolia. The genus is currently monotypic, only including the type species A. giganticus. The first remains were found in 1989 during a Mongolian-Russian field expedition and later described in 1999. Remains at the type locality of Achillobator may represent additional specimens. It represents the first and largest dromaeosaurid known from the Bayan Shireh Formation.

<span class="mw-page-title-main">Hell Creek Formation</span> Geological formation in the United States

The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. The site of Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation. In 1966, the Hell Creek Fossil Area was designated as a National Natural Landmark by the National Park Service.

<i>Pyroraptor</i> Extinct genus of dinosaurs

Pyroraptor is an extinct genus of paravian dinosaur, probably a dromaeosaurid or unenlagiid, from the Late Cretaceous Ibero-Armorican island, of what is now southern France and northern Spain. It lived during the late Campanian and early Maastrichtian stages, approximately 70.6 million years ago. It is known from a single partial specimen that was found in Provence in 1992, after a forest fire. The animal was named Pyroraptor olympius by Allain and Taquet in 2000.

<i>Zapsalis</i> Extinct genus of dinosaurs

Zapsalis is a genus of dromaeosaurine theropod dinosaurs. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include teeth but no other remains.

<i>Pectinodon</i> Genus of bird-like dinosaur

Pectinodon is a genus of troodontid theropod dinosaurs from the end of the Maastrichtian age of the Late Cretaceous period (66 mya). It currently contains a single valid species, Pectinodon bakkeri, known only from teeth.

<i>Axestemys</i> Extinct genus of turtles

Axestemys is an extinct genus of softshell turtle that lived from the Late Cretaceous to the Eocene in western North America and Europe.

<span class="mw-page-title-main">Dromaeosaurinae</span> Extinct subfamily of dinosaurs

Dromaeosaurinae is a subfamily of the theropod group Dromaeosauridae. The earliest dromaeosaurine is Utahraptor, dating back to the Early Cretaceous in North America. Some isolated teeth seems to represent an indeterminate species of dromaeosaurine, coming from the Late Jurassic in Africa, which could potentially push their range to an earlier time period.

<i>Austroraptor</i> Genus of theropod dinosaurs

Austroraptor is a genus of dromaeosaurid theropod dinosaur that lived during the Campanian and Maastrichtian ages of the Late Cretaceous period in what is now Argentina.

<span class="mw-page-title-main">Saurornitholestinae</span> Extinct subfamily of dinosaurs

Saurornitholestinae is a subfamily of the theropod group Dromaeosauridae. The saurornitholestines currently include monotypic genera Atrociraptor marshalli, Saurornitholestes langstoni, and possibly Bambiraptor feinbergi and Acheroraptor temertyorum. All are medium-sized dromaeosaurs from the Late Cretaceous of western North America. The group was originally recognized by Longrich and Currie as the sister taxon to a clade formed by the Dromaeosaurinae and Velociraptorinae. However, not all phylogenetic analyses recover this group and/or with the same proposed genera.

This is an overview of the fossil flora and fauna of the Maastrichtian-Danian Hell Creek Formation.

<span class="mw-page-title-main">Eudromaeosauria</span> Extinct clade of dinosaurs

Eudromaeosauria is a subgroup of terrestrial dromaeosaurid theropod dinosaurs. They were small to large-sized, feathered hypercarnivores that flourished in the Cretaceous Period.

<span class="mw-page-title-main">Timeline of dromaeosaurid research</span>

This timeline of dromaeosaurid research is a chronological listing of events in the history of paleontology focused on the dromaeosaurids, a group of sickle-clawed, bird-like theropod dinosaurs including animals like Velociraptor. Since the Native Americans of Montana used the sediments of the Cloverly Formation to produce pigments, they may have encountered remains of the dromaeosaurid Deinonychus hundreds of years before these fossils came to the attention of formally trained scientists.

<i>Dakotaraptor</i> Extinct chimaeric genus of dinosaurs

Dakotaraptor is a potentially chimaeric genus of maniraptoriform theropod dinosaur that lived in western North America during the Late Cretaceous period. The remains have been found in the Maastrichtian-aged Hell Creek Formation, dated to the very end of the Mesozoic era, making Dakotaraptor potentially one of the last surviving dromaeosaurids, though other researchers have disputed its classification. The remains of D. steini were discovered in a multi-species bonebed. Elements of the holotype and referred specimens were later found to belong to trionychid turtles, and it is unclear whether further analysis of potential non-dromaeosaurid affinities of the holotype and referred material can be properly conducted, because currently the type specimen is housed in private collection. Phylogenetic analyses of D. steini place it in a variety of positions within Dromaeosauridae.

<i>Dineobellator</i> Extinct genus of dinosaurs

Dineobellator is a genus of dromaeosaurid theropod dinosaur that lived in North America during the Late Cretaceous period 68 million years ago. The remains have been found in the Maastrichtian stage of the Naashoibito Member at the Ojo Alamo Formation, New Mexico.

References

  1. 1 2 3 4 5 6 7 Evans, D.C.; Larson, D.W.; Currie, P.J. (2013). "A new dromaeosaurid (Dinosauria: Theropoda) with Asian affinities from the latest Cretaceous of North America". Naturwissenschaften. 100 (11): 1041–9. Bibcode:2013NW....100.1041E. doi:10.1007/s00114-013-1107-5. PMID   24248432. S2CID   14978813.
  2. ↑ Powers, Mark J.; Fabbri, Matteo; Doschak, Michael R.; Bhullar, Bhart-Anjan S.; Evans, David C.; Norell, Mark A.; Currie, Philip J. (2022). "A new hypothesis of eudromaeosaurian evolution: CT scans assist in testing and constructing morphological characters". Journal of Vertebrate Paleontology. 41 (5): e2010087. doi:10.1080/02724634.2021.2010087. S2CID   247039404.
  3. ↑ Jasinski, Steven E.; Sullivan, Robert M.; Carter, Aja M.; Johnson, Erynn H.; Dalman, Sebastian G.; Zariwala, Juned; Currie, Philip J. (2022-11-07). "Osteology and reassessment of Dineobellator notohesperus, a southern eudromaeosaur (Theropoda: Dromaeosauridae: Eudromaeosauria) from the latest Cretaceous of New Mexico" . The Anatomical Record: ar.25103. doi:10.1002/ar.25103. ISSN   1932-8486. PMID   36342817. S2CID   253382718.
  4. ↑ Husson, D.E.; Galbrun, B.; Laskar, J.; Hinnov, L.A.; Thibault, N.; Gardin, S.; Locklair, R.E. (2011). "Astronomical calibration of the Maastrichtian (Late Cretaceous)". Earth and Planetary Science Letters. 305 (3–4): 328–340. Bibcode:2011E&PSL.305..328H. doi:10.1016/j.epsl.2011.03.008.
  5. 1 2 3 4 5 6 7 8 Weishampel, D.B.; Dodson, P.; Osmólska, H. (2004). The Dinosauria (2nd ed.). Berkeley, California: University of California Press. pp.  861. ISBN   0520242092.
  6. 1 2 DePalma, R.A.; Burnham, D.A.; Martin, L.D.; Larson, P.L.; Bakker, R.T. (2015). "The First Giant Raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation". Paleontological Contributions (14): 1–16. doi: 10.17161/paleo.1808.18764 . S2CID   17099603.
  7. 1 2 Longrich, N.R.; Tokaryk, T.; Field, D.J. (2011). "Mass extinction of birds at the Cretaceous-Paleogene (K-Pg) boundary". Proceedings of the National Academy of Sciences. 108 (37): 15253–15257. Bibcode:2011PNAS..10815253L. doi: 10.1073/pnas.1110395108 . PMC   3174646 . PMID   21914849.
  8. 1 2 Lamanna, M.C.; Sues, H.D.; Schachner, E.R.; Lyson, T.R. (2014). "A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America". PLOS ONE. 9 (3): e92022. Bibcode:2014PLoSO...992022L. doi: 10.1371/journal.pone.0092022 . PMC   3960162 . PMID   24647078.
  9. ↑ Triebold, M. (1997). "The Sandy site: Small dinosaurs from the Hell Creek Formation of South Dakota". In Wolberg, D.; Stump, E.; Rosenberg, G. (eds.). Dinofest International: Proceedings of a Symposium Sponsored by Arizona State University Academy of Natural Science. pp. 245–248.
  10. ↑ Martin, L.D.; Kurochkin, E.N.; Tokaryk, T.T. (2012). "A new evolutionary lineage of diving birds from the Late Cretaceous of North America and Asia". Palaeoworld . 21: 59–63. doi:10.1016/j.palwor.2012.02.005.
  11. ↑ Maltese, A. (17 December 2013). "Giant Oviraptor Tracks from the Hell Creek". RMDRC paleo lab. Blogspot. Retrieved 17 December 2013.
  12. ↑ Ott, C.J.; Larson, P.L. (2010). "A New, Small Ceratopsian Dinosaur from the Latest Cretaceous Hell Creek Formation, Northwest South Dakota, United States: A Preliminary Description". In Ryan, M.J.; Chinnery-Allgeier, B.J.; Eberth, D.A. (eds.). New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Bloomington: Indiana University Press. p. 656. ISBN   9780253353580.
  13. ↑ Campione, N.S.E.; Evans, D.C. (2011). "Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest Cretaceous Megaherbivore Diversity in North America". PLOS ONE. 6 (9): e25186. Bibcode:2011PLoSO...625186C. doi: 10.1371/journal.pone.0025186 . PMC   3182183 . PMID   21969872.
  14. ↑ Bakker, R.T.; Sullivan, R.M.; Porter, V.; Larson, P.; Saulsbury, S.J. (2006). "Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota". In Lucas, S.G.; Sullivan, R.M. (eds.). Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin. Vol. 35. pp. 331–345.
  15. 1 2 3 4 5 Kielan-Jaworowska, Z.; Cifelli, R.; Luo, Z-X. (2004). Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure. New York: Columbia University Press. ISBN   9780231119184. OCLC   61160163.
  16. 1 2 Wilson, G.P. (2013). "Mammals across the K/Pg boundary in northeastern Montana, U.S.A.: Dental morphology and body-size patterns reveal extinction selectivity and immigrant-fueled ecospace filling". Paleobiology. 39 (3): 429–469. doi:10.1666/12041. S2CID   36025237.
  17. 1 2 Archibald, J.D.; Zhang, Y.; Harper, T.; Cifelli, R.L. (2011). "Protungulatum, Confirmed Cretaceous Occurrence of an Otherwise Paleocene Eutherian (Placental?) Mammal". Journal of Mammalian Evolution. 18 (3): 153–161. doi:10.1007/s10914-011-9162-1. S2CID   16724836.
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