Haplocanthosaurus

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Haplocanthosaurus
Temporal range: Late Jurassic, 155–152  Ma
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Haplocanthosaurus in Cleveland Museum of Natural History.jpg
Updated mount in Cleveland Museum of Natural History
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Sauropodomorpha
Clade: Sauropoda
Superfamily: Diplodocoidea
Family: Haplocanthosauridae
Bonaparte, 1999
Genus: Haplocanthosaurus
Hatcher, 1903 (conserved name)
Type species
Haplocanthosaurus priscus
(Hatcher, 1903) (conserved name)
Other species
  • H. delfsi
    McIntosh & Williams, 1988
Synonyms

Haplocanthosaurus (meaning "simple spined lizard") is a genus of intermediate sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period (Kimmeridgian stage), 155 to 152 million years ago. [2] The type species is H. priscus, and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado, United States. Haplocanthosaurus specimens have been found in the very lowest layer of the Morrison Formation, along with Hesperosaurus mjosi , Brontosaurus yahnahpin , and Allosaurus jimmadseni . [3]

Contents

Discovery

Quarry map showing holotype of H. priscus Haplocanthosaurus in situ.jpg
Quarry map showing holotype of H. priscus

There are four known specimens of Haplocanthosaurus: one of H. delfsi, and three of H. priscus. Of these, the type of H. delfsi is the only one complete enough to mount. The mounted specimen of H. delfsi now stands in the Cleveland Museum of Natural History, albeit with a completely speculative replica skull, as the actual skull was not recovered. Present in stratigraphic zones 1, 2, and 4. [4] Recently described specimens from a different region of the Morrison Formation were assigned to Haplocanthosaurus in 2014. The study describing them noted that Haplocanthosaurus is known for certain from at least four specimens, assigned to H. priscus (CM 572), H. utterbacki (=H. priscus; CM 879), H. delfsi (CMNH 10380), [5] and H. sp. (MWC 8028). Up to seven additional specimens have been assigned to Haplocanthosaurus? or Haplocanthosauridae indet. [1] One potential specimen has been nicknamed "Big Monty," for its discovery in Montana. It has been claimed to measure an incredible 34 meters (110 ft) long. However, much controversy surrounds the specimen and, as such, little is truly known about it. [6]

Description

Life restoration Haplocanthosaurus.jpg
Life restoration

Haplocanthosaurus was one of the smallest sauropods of the Morrison. [3] While some Morrison sauropods could reach lengths of over 20 meters (or over 66 feet), Haplocanthosaurus was smaller, reaching a total length of 14.8 meters (49 feet) and an estimated weight of 12.8 metric tons (14.1 short tons). [7]

Haplocanthosaurus is known from many elements, mostly of vertebra. In the middle and cervical caudals of Apatosaurus , Camarasaurus , Cetiosaurus and Haplocanthosaurus, the intraprezygapophyseal lamina is separate from the root of the neural canal by a vertical midline lamina. In the last few caudals and the most cranial dorsals, the lateral edge of the prezygapophyseal lamina becomes widened and roughened. Hatcher (1901) interpreted this as forming the attachment area for the muscles from which the scapular blade was suspended. [8]

The dorsoventrally elongate oval outlines are characteristic of Haplocanthosaurus with only Camarasaurus also possessing them. The parapophyses remaining as oval facets on the craniolateral margin, and the sacral spines 1-3 fused are also found in both Haplocanthosaurus and Camarasaurus. [8]

The Cetiosaurus specimen OUMNH J13695 has a low horizontal ridge on each of its lateral surfaces, creating a slightly subhexagonal transverse cross-section, a feature also seen on Cetiosauriscus , the anterior caudals of Haplocanthosaurus, and caudals 15-30 of Omeisaurus . Also, the area around the periphery of each articular face is flattened, creating a ‘bevelled’ appearance, and also occurs in Haplocanthosaurus and Cetiosauriscus. [9]

Distinguishing characteristics

Haplocanthosaurus is distinguished by dorsal vertebra lacking cranial centrodiapophyseal laminae. Also, it is distinguished by elongate intrapostzygapophyseal laminae, dorsoventrally directed dorsal transverse processes that approach the height of the neural spines, and the distal end of the scapular blade being dorsally and ventrally expanded. [8]

Classification

Diagram showing known remains of specimen CM 879 Haplocanthosaurus utterbacki skeletal.png
Diagram showing known remains of specimen CM 879
Specimen FHPR 1106 Haplocanthosaurus vernal 1.jpg
Specimen FHPR 1106

Haplocanthosaurus priscus was originally named Haplocanthus priscus by John Bell Hatcher in 1903. Soon after his original description, Hatcher came to believe the name Haplocanthus had already been used for a genus of acanthodian fish (Haplacanthus, named by Louis Agassiz in 1845), and was thus preoccupied. Hatcher re-classified his sauropod later in 1903, giving it the new name Haplocanthosaurus. [10] However, the name was not technically preoccupied at all, since there was a variation in spelling: the fish was named Haplacanthus, not Haplocanthus. While Haplocanthus technically remained the valid name for this dinosaur, Hatcher's mistake was not noticed until many years after the name Haplocanthosaurus had become fixed in scientific literature. When the mistake was finally discovered, a petition was sent to the ICZN (the body which governs scientific names in zoology), which officially discarded the name Haplocanthus and declared Haplocanthosaurus the official name (ICZN Opinion #1633).

Originally described as a "cetiosaurid", José Bonaparte decided in 1999 that Haplocanthosaurus differed enough from other sauropods to warrant its own family, the Haplocanthosauridae. [11]

Phylogenetic studies have failed to clarify the exact relationships of Haplocanthosaurus with any certainty. Studies have variously found it to be more primitive than the neosauropods, [12] a primitive macronarian (related to the ancestor of more advanced forms such as Camarasaurus and the brachiosaurids), [13] or a very primitive diplodocoid, more closely related to Diplodocus than to titanosaurs, but more primitive than rebbachisaurids. [14]

In 2005, Darren Naish and Mike Taylor reviewed the various proposed positions of Haplocanthosaurus in their study of diplodocoid phylogeny. They found it could be a non-neosauropod eusauropod, a basal macronarian, or a basal diplodocoid. [15] In 2011, an analysis by Whitlock recovered Haplocanthosaurus as the basalmost member of the Diplodocoidea, the third potentiality of Taylor & Naish. [16] In 2015, a specimen-level phylogenetic analysis was published, finding Haplocanthosaurus to be a confirmed diplodocoid, either very basal, or more derived than rebbachisaurids. Their implied weighting cladogram is shown below. [17]

Outdated H. delfsi skeleton mount,
' Cleveland Museum of Natural History Cleveland Museum Haplocanthosaurus.jpg
Outdated H. delfsi skeleton mount, ' Cleveland Museum of Natural History
  Diplodocoidea  

Related Research Articles

<i>Apatosaurus</i> Sauropod dinosaur genus from Late Jurassic period

Apatosaurus is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, A. ajax, in 1877, and a second species, A. louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t. A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t.

<i>Camarasaurus</i> Camarasaurid sauropod dinosaur genus from Late Jurassic Period

Camarasaurus was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch, between 155 and 145 million years ago.

<span class="mw-page-title-main">Diplodocidae</span> Extinct family of dinosaurs

Diplodocids, or members of the family Diplodocidae, are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including Diplodocus and Supersaurus, some of which may have reached lengths of up to 42 metres (138 ft).

<span class="mw-page-title-main">Como Bluff</span> United States historic place

Como Bluff is a long ridge extending east–west, located between the towns of Rock River and Medicine Bow, Wyoming. The ridge is an anticline, formed as a result of compressional geological folding. Three geological formations, the Sundance, the Morrison, and the Cloverly Formations, containing fossil remains from the Late Jurassic of the Mesozoic Era are exposed.

<i>Cetiosauriscus</i> Genus of reptiles (fossil)

Cetiosauriscus is a genus of sauropod dinosaur that lived between 166 and 164 million years ago during the Callovian in what is now England. A herbivore, Cetiosauriscus had – by sauropod standards – a moderately long tail, and longer forelimbs, making them as long as its hindlimbs. It has been estimated as about 15 m (49 ft) long and between 4 and 10 t in weight.

<span class="mw-page-title-main">Diplodocoidea</span> Extinct superfamily of dinosaurs

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<i>Camarasaurus lewisi</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">Camarasauridae</span> Extinct family of dinosaurs

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

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<i>Camarasaurus supremus</i> Species of sauropod dinosaur

Camarasaurus supremus is a species of sauropod dinosaur that lived during the Jurassic period in what is now the western United States. It is the type species of Camarasaurus, which also includes the species Camarasaurus grandis, Camarasaurus lentus, and Camarasaurus lewisi. C. supremus was discovered by the paleontologist Edward Drinker Cope in 1877, at the outset of the Bone Wars, a period of scientific competition between Cope and his rival Othniel Marsh. C. supremus is the largest and geologically youngest species in its genus, and was contemporary with several other exceptionally large dinosaurs, such as Saurophaganax and Maraapunisaurus. Despite being the first discovered species of Camarasaurus, C. supremus is relatively rare and poorly known.

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<i>Camarasaurus lentus</i> Species of sauropod

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

Amphicoelias is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during the Tithonian of what is now Colorado, United States. Amphicoelias was moderately sized at about 18 metres (59 ft) in length and 15 metric tons in body mass, shorter than its close relative Diplodocus. Its hindlimbs were very long and thin, and its forelimbs were proportionally longer than in relatives.

<i>Diplodocus</i> Genus of diplodocid sauropod dinosaurs (fossil)

Diplodocus is an extinct genus of diplodocid sauropod dinosaurs known from the Late Jurassic of North America. The first fossils of Diplodocus were discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique.

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References

  1. 1 2 Forster, J.R.; Wedel, M.J. (2014). "Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado" (PDF). Volumina Jurassica. 12 (2): 197–210. doi:10.5604/17313708.1130144 (inactive 2024-09-12).{{cite journal}}: CS1 maint: DOI inactive as of September 2024 (link)
  2. Turner, C.E. and Peterson, F., (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A." Pp. 77–114 in Gillette, D.D. (ed.), Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication 99-1.
  3. 1 2 Foster, J. (2007). Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. 389pp.
  4. Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  5. McIntosh, J.S., Williams, M.E. (1988). "A new species of sauropod dinosaur, Haplocanthosaurus delfsi sp. nov., from the Upper Jurassic Morrison Fm. of Colorado". Kirtlandia. 43: 3–26 via Biodiversity Heritage Library.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. Ronson, Jacqueline (5 July 2016). "Is Nate Murphy Holding a Dinosaur for Ransom?". Inverse. Retrieved 2021-05-06.
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  17. Tschopp, E.; Mateus, O.; Benson, R.B.J. (2015). "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)". PeerJ. 3: e857. doi: 10.7717/peerj.857 . PMC   4393826 . PMID   25870766.