Utahraptor

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Utahraptor
Temporal range:
Ma
↓
Reconstructed skeleton in BYU Museum of Paleontology
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Dromaeosauridae
Clade: †Eudromaeosauria
Subfamily: †Dromaeosaurinae
Genus: †Utahraptor
Kirkland, Gaston & Burge, 1993
Type species
†Utahraptor ostrommaysi
Kirkland et al., 1993

Utahraptor (meaning "

paleontologist James Kirkland and colleagues with the type species Utahraptor ostrommaysi, based on fossils that had been unearthed earlier from the Cedar Mountain Formation of Utah. Later, many additional specimens were described including those from the skull
and postcranium in addition to those of younger individuals.

It was a heavily built, ground-dwelling,

teeth that were used in conjunction with a large "killing claw" on its second toe to dispatch its prey. Its skull was boxy and elongated, akin to other dromaeosaurids like Dromaeosaurus and Velociraptor
.

Utahraptor is in the subfamily

pursuit predators
.

Discovery and naming

Premaxilla of BYU 7510 14585

The first specimens of Utahraptor were found in 1975 by Jim Jensen in the Dalton Wells Quarry of Utah, near the town of Moab, but did not receive much attention. After a find of a large claw by Carl Limone in October 1991, James Kirkland, Robert Gaston and Donald Burge uncovered further remains of Utahraptor in 1991 in the Gaston Quarry in Grand County, Utah, within the Yellow Cat and Poison Strip members of the Cedar Mountain Formation. The holotype of Utahraptor, CEUM 184v.86, consists of a second pedal ungual, with potentially assigned elements from other specimens: pedal ungual CEUM 184v.294, tibia CEUM 184v.260 and premaxilla CEUM 184v.400.[1] The holotype is housed in the paleontology collections of the Prehistoric Museum at Utah State University Eastern. Brigham Young University, the depository of Jensen's finds, currently houses the largest collection of Utahraptor fossils. [1]

The type species, Utahraptor ostrommaysi, was named by Kirkland, Gaston and Burge in June 1993. The genus name Utahraptor is in reference to Utah, where the remains were found. The specific name, ostrommaysi, is in honor to John Ostrom for his investigations on Deinonychus and its relationships to birds, as well as Chris Mays, who helped in the research of Utahraptor by founding Dinamation.[1] From his description, Kirkland stated the meaning of genus name to be "Utah's predator,"[1] but the Latin word raptor translates to 'robber' or 'plunderer', not 'predator'.[2] Earlier, it had been intended to name the species "U. spielbergi" after film director Steven Spielberg, in exchange for him funding paleontological research, but no agreement could be reached on the amount of financial assistance.[3]

Pedal ungual II of CEUM 184v.294, housed at the Prehistoric Museum, USU Eastern.

In 2000, the specific name was emended by

genitive form from two persons with different names, Costa and David conclude that the original spelling ostrommaysi has to be regarded as an arbitrary combination of letters and not a correctly formed genitive form. Under this reasoning, ostrommaysorum has no valid use and the original spelling ostrommaysi does not need to be emended. Other alternative and also invalid spellings were used in scientific literature, such as ostromaysi, ostromaysorum, ostromayssorum, ostromayorum and ostrommaysori.[5]

For instance, some elements were wrongly referred to the genus. The lacrimal bone of the specimen CEUM 184v.83 turned out to be a postorbital from the ankylosaur Gastonia. Britt et al. also suggested that the previously identified manual unguals of the specimens M184v.294, BYU 9438 and BYU 13068 are indeed pedal unguals.[6] This suggestion was confirmed by Senter in 2007.[7]

Description

Restoration
Utahraptor specimens compared in size to a 1.8-metre-tall (5.9 ft) human

Utahraptor was one of, if not the largest and heaviest of all dromaeosaurids, with the largest assigned specimen BYUVP 15465 having a femoral length of 56.5–60 cm (22.2–23.6 in).[8][9]

Upon the description of Utahraptor, its dimensions were estimated as much as 7 m (23 ft) in length and somewhat less than 500 kg (1,100 lb), comparable in weight to a polar bear.[1] Various authors agree in that Utahraptor is best estimated around 5–6 m (16–20 ft) long,[10][11] and weighing up to 250–350 kg (550–770 lb).[12][13][14]

Although

dromaeosaurids had feathers.[18]

Reconstructed skull, BYU

According to Kirkland et al. in 1993, Utahraptor can be recognized by a few special

quadratojugal without a posterior process, the presence of a well-developed notch between the lesser trochanter and greater trochanter, and dorsal vertebrae that lack pleurocoels.[19] Like other dromaeosaurids, Utahraptor had a large curved claw on the second toe of each foot. The second pedal ungual is preserved at 22 cm (8.7 in) in length and is estimated to reach 24 cm (9.4 in) in restoration.[1]

Classification

Utahraptor is a member of the family Dromaeosauridae, a clade of theropod dinosaurs commonly known as "raptors". Utahraptor is the largest known genus in the family and belongs to the same clade of other notable dinosaurs such as Velociraptor, Deinonychus, or Dromaeosaurus. It is classified in the subfamily Dromaeosaurinae, which is found in the clade Eudromaeosauria.[1]

In 2015, Utahraptor was found to be closely related to the smaller Dromaeosaurus and the giant Mongolian and North American dromaeosaurid genera Achillobator and Dakotaraptor:[18]

Size of Utahraptor (5) compared with other dromaeosaurs
Eudromaeosauria

The cladogram below is the result of a cladistic analysis conducted by Cau et al. in 2017.[20]

Eudromaeosauria

Paleobiology

Predatory behavior

Dinosaur Museum Aathal

Kirkland et al. noted that given the huge size of Utahraptor, it was not as fast as

prey and retain balance while kicking it; in contrast to this, the heavily built Utahraptor may have been able to deliver kicks without the risk of losing balance, freeing the hands and using them to dispatch prey.[1]

According to

therizinosaurs. Its robust build and large sickle claw indicate it was well suited to hunting such prey. Like other dromaeosaurine dromaeosaurids, it may have also relied heavily on its jaws to dispatch prey—more so than other types of dromaeosaurids, such as velociraptorines.[21]

Social behavior

In 2001, Kirkland et al. pursued a graduate student's discovery of a bone protruding from a 9-ton fossil block of

Cleveland-Lloyd Quarry and California's La Brea Tar Pits house such predator traps. Examination of the fossils are ongoing after a decade of excavation, but if Kirkland is correct, it may be one of the best-preserved predator traps ever discovered. The fossils may further reveal aspects into the behavior of Utahraptor, such as whether it might have hunted in groups like Deinonychus was believed to have done. Whether all the Utahraptor individuals were mired simultaneously or were drawn in, one-by-one is unclear.[22] Further examination of the block suggests that the number of Utahraptor remains may be double the amount previously assumed.[23]

While dinosaur behavior can only be theorized, it was later discovered in 2020 that Deinonychus may not have had complex social behavior seen in some pack-hunting animals alive in the modern era, based on differing dietary preferences in adults and juveniles indicating they did not live in long-term family groups. It is unknown if this lack of complex, cooperative social behavior also extended to Utahraptor.[24]

Paleoenvironment

Utahraptor lived in the lower part of the

palynoflora, Middle Berriasian–Early Hauterivian ages were provisionally assigned.[27] However, the Yellow Cat Member is divided into distinct "lower" and "upper" layers, and Utahraptor fossils are only currently known within the upper Yellow Cat Member.[28]

Utahraptor (red, right) and other dinosaur fauna from the Cedar Mountain Formation

Utahraptor was unearthed from the Yellow Cat Member, which during the

Anthocerotophyta) and other vascular plants.[27] During the description of Mierasaurus, it was interpreted that there was also a waterlogged bog-like environment.[29] There is believed to have been a short wet season. This is supported by the presence of charred spores and other carbonized plant debris in the pollen maceral that indicate the occurrence of ancient wildfires ignited during periods of low precipitation.[21][27]

sauropods Cedarosaurus and Moabosaurus.[29][28][30] The only known mammal from the Upper Yellow Cat Member is Cifelliodon.[31]

Other non-dinosaur or

sharks.[28]

Additional

caudal vertebra and fragmented tail (UMNH VP 20209) were also present.[34]

Cultural significance

Raptor Red was published in 1995, and features the fictionalized story of a female Utahraptor. Written by paleontologist Robert T. Bakker, it was positively regarded by mainstream reviewers, though updates to the science have rendered some of the story line facts presented untrue and the paleontology community was critical of fossil record inaccuracies.[35][36] Bakker's anthropomorphosis of the titular Red was particularly praised.[37][38][39]

In 2018, it was proposed by a 10-year-old elementary school student, Kenyon Roberts, that Utahraptor be the Utah state dinosaur, an act that was approved by the Senate.[40] Initially Utahraptor would have replaced another dinosaur, Allosaurus, as the state's official fossil, but it was decided that Utahraptor would be another symbol of the state.[41] In 2021, Steve Eliason[42][43] successfully created a proposal for Utahraptor State Park where the block was discovered, proposed by the same Utah student, Kenyon Roberts. It was approved by the state House.[44]

See also

References

  1. ^ a b c d e f g h i Kirkland, J. I.; Burge, D.; Gaston, R. (1993). "A large dromaeosaurid (Theropoda) from the Lower Cretaceous of Eastern Utah". Hunteria. 2 (10): 1–16.
  2. ^ "raptŏr - ONLINE LATIN DICTIONARY". Online Latin Dictionary.
  3. ^ Adams, Brooke (June 15, 1993). "Director Loses Utahraptor Name Game". Deseret News. Archived from the original on October 23, 2016.
  4. ^ Olshevsky, G., 2000, An annotated checklist of dinosaur species by continent. Mesozoic Meanderings 3: 1-157
  5. S2CID 166691677
    .
  6. ^ Britt, B. B.; Chure, D. J.; Stadtman, K. L.; Madsen, J. H.; Scheetz, R. D.; Burge, D. L. (2001). "New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah". Journal of Vertebrate Paleontology. 21 (3): 36A.
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  8. PMID 19816582
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  9. ISSN 0016-7568
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  10. PMID 19129109
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  11. ISBN 9780691231570
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  12. doi:10.1111/pala.12329
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  13. PMID 24802911. Supporting Information
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  18. ^
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  19. S2CID 83572446
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  21. ^
    ISBN 9780691167664
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  22. S2CID 132388318
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  23. ^ Williams, Carter (February 25, 2021). "Several more Utahraptor fossils discovered from 136M-year-old block 1st found in Utah". KSL.com. Deseret Digital Media. Archived from the original on February 27, 2021.
  24. S2CID 219059665
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  25. ^ Holtz, T. R.; Rey, L. V. (2007). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House. Supplementary Information 2012 Weight Information
  26. doi:10.1016/j.earscirev.2010.05.001
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  27. ^
    S2CID 210296827
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  28. ^ a b c d e Kirkland, J.I. (December 1, 2016). "The Lower Cretaceous in East-Central Utah—The Cedar Mountain Formation and its Bounding Strata". Geology of the Intermoutain West. 3: 1–130.
  29. ^
    PMID 29085006
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  30. S2CID 50350241. Archived from the original
    (PDF) on March 5, 2019.
  31. S2CID 43921185
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  32. S2CID 86258448
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  33. S2CID 220429286
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  34. PMID 22615813
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  35. ^ Holtz, Thomas R. (September 12, 1995). "Raptor Red: a review (long)". Archives of the DINOSAUR Mailing List. Archived from the original on March 3, 2021. Retrieved December 5, 2014.
  36. ^ Kanipe, Jeff (February 1996). "Dino Redux". Earth. 5 (1): 66–68.
  37. ^ Naughton, John (September 5, 1995). "At home with a Jurassic monster". The Times.
  38. ^ Chander, David (November 13, 1995). "In his field, Robert Bakker walks alone". Boston Globe. p. 29.
  39. ^ Johnson, Eric (September 1995). "Book Reviews: Fiction". Library Journal. 120 (14): 205.
  40. ^ Nixon, Nicole (February 12, 2018). "Senate Gives Utahraptor A Roar Of Approval". kuer.org. Retrieved February 13, 2018.
  41. ^ Roche, Lisa Riley (February 12, 2018). "Senate approves bill making Utahraptor state dinosaur". Deseret News. Retrieved February 18, 2018.
  42. ^ Eliason, Steve; Iwamoto, Jani (2020). "H.B. 322 - Utahraptor State Park". Utah State Legislature.
  43. ^ McKellar, Katie (February 18, 2020). "Utahraptor State Park would protect discovery site of Utah's namesake dinosaur". Deseret News. Retrieved January 17, 2024.
  44. ^ Johnson, Jan (March 2, 2021). "Utah Considers State Park Named For Utahraptor Dinosaur". NPR.org. Retrieved March 4, 2021.

External links

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