Galeamopus

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Galeamopus
Temporal range: Late Jurassic, 155–152.9  Ma
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WLA hmns Diplodocus.jpg
Mounted G. hayi holotype skeleton, Houston Museum of Natural Science
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: Diplodocidae
Subfamily: Diplodocinae
Genus: Galeamopus
Tschopp et al., 2015
Type species
Diplodocus hayi
Holland, 1924
Species
  • G. hayi(Holland, 1924)
  • G. pabstiTschopp & Mateus, 2017
Synonyms

Diplodocus hayiHolland, 1924 (type)

Galeamopus is a genus of herbivorous diplodocid sauropod dinosaurs. It contains two known species: Galeamopus hayi, known from the Late Jurassic lower Morrison Formation (Kimmeridgian age, about 155 million years ago) of Wyoming, United States, and Galeamopus pabsti, known from the Late Jurassic fossils from Wyoming and Colorado. The type species is known from one of the most well preserved diplodocid fossils, a nearly complete skeleton with associated skull.

Contents

History

The skull of the holotype specimen of Galeamopus pabsti, SMA 00011, nicknamed "Max" Galeamopus pabsti skull.jpg
The skull of the holotype specimen of Galeamopus pabsti, SMA 00011, nicknamed "Max"

The first specimen referred to Galeamopus was collected by Marshall P. Felch in September, 1884 at his quarry in Garden Park, Colorado. The specimen consisted of a partial skull and mandibles, which Felch sent to his employer at the Yale Peabody Museum, Othniel Charles Marsh, but was later deposited at the National Museum of Natural History (USNM V 2673). It was referred to Diplodocus for many years until Tschopp et al referred the remains to Galeamopus in 2015 [1] and Galeamopus pabsti in 2017. [2]

The type specimen of Galeamopus was discovered by fossil hunter William H. Utterback in 1902 near Sheridan, Wyoming, in the Red Fork Powder River Quarry A for the Carnegie Museum of Natural History. [1] [3] The specimen was composed of a braincase, partial vertebral column, and several other postcranial elements. [3] [1] In 1906, the skeleton was referred to Diplodocus by William Jacob Holland when he described its braincase. [4] The specimen was classified by Holland as a new species of Diplodocus, Diplodocus hayi, in 1924. The specific name honored Oliver Perry Hay. [3]

Another Galeamopus specimen was discovered and collected by Peter Kaisen in 1903 at Bone Cabin Quarry, Wyoming during an American Museum of Natural History expedition. [1] [2] This specimen (AMNH 969) consisted of a nearly complete skull and the atlas-axis complex preserved in articulation, [1] and it was also referred to Diplodocus until Tschopp’s reassessment, [2] [1] which placed it as a specimen of Galeamopus hayi. [2]

In 2015, it was renamed as the separate genus Galeamopus by Emanuel Tschopp, Octávio Mateus and Roger Benson. The generic name is derived from Latin galeam, the accusative of galea, "helmet", and opus, "need". The combination is intended as a translation of Wil-helm, literally "want helmet", in reference to the first name of both Utterback and Holland. The name is at the same time an allusion to the fact that the brittle braincase of the type specimen is in need of a helmet. [1]

The genoholotype is HMNS 175 (previously CM 662), the original skeleton. It was found in layer of the lower Morrison Formation dating from the Kimmeridgian. This specimen is also the holotype of Galeamopus hayi, the combinatio nova of the type species D. hayi. Several other specimens were referred to the genus Galeamopus but not to Galeamopus hayi. [1] All of the specimens referred to Galeamopus are from the Morrison Formation, with 3 of the 4 specimens collected in Wyoming. [1]

SMA 0011, a skeleton nicknamed "Max" and found in June 1995 at the Howe-Stephens Quarry, was considered sufficiently different from the others to consider naming a separate species for it. [1] The skeleton included a nearly complete skull and mandibles and the majority of the anterior postcranial skeleton. [2] In 2017, the "Max" specimen was made the type specimen of a second Galeamopus species, G. pabsti, by Tschopp and Mateus. It was named after the Swiss paleontologist Dr. Ben Pabst, who discovered the specimen and helped mount the skeleton at Sauriermuseum Aathal. [2]

Description

G. pabsti skeleton in Cincinnati Museum Center at Union Terminal Galeamopus pabsti skeleton.jpg
G. pabsti skeleton in Cincinnati Museum Center at Union Terminal

The 2015 study established seven distinguishing traits of the genus as such. These were autapomorphies, unique derived characters. On the back of the skull, the paroccipital process is curved in side view. The teeth have paired wear facets. The first neck vertebra, the atlas, has a neural spine with processes pointing to the front and the inside, which are separate from the rear wing of the spine. This rear wing shows a continuous transverse width over most of its length. The neural arch of the atlas has on each side of its base a small triangular spur. The second neck vertebra, the axis, has a neural spine with a knob-shaped bump on the front end of the ridge on its front side. With the middle and rear neck vertebrae, the ridge between the rear joint processes, the postzygapophyses, does not extend beyond the rear edge of the neural arch. [1]

The study also determined six autapomorphies of the type species Galeamopus hayi alone. The part of the parietal bone forming the edge between the rear skull and the skull roof is low, with a height less than that of the foramen magnum . The appending basipterygoid processes at the underside of the braincase strongly diverge at an angle of more than 60°. The ulna of the lower arm is long, with a minimum length equalling 76% of the humerus, upper arm bone, length. The surface on the radius contacting the ulna is limited in size and relatively smooth. The joint surface at the underside of the radius is bevelled relative to the shaft, at an angle of about 15°. The outer edge of the top surface of the shinbone forms a pinched process, behind the cnemial crest at the front. [1]

Hypothetical life restoration of G. hayi Galeamopus.jpg
Hypothetical life restoration of G. hayi

Combined, there are thirteen autapomorphies present in Galeamopus, exactly the minimum the study used as a criterion to distinguish separate genera. [1]

Relationships

G. hayi skull (specimen AMNH 969) Galeamopus hayi AMNH 969.jpg
G. hayi skull (specimen AMNH 969)

The cladogram below shows one hypothesis on the relationships of Galeamopus to other diplodocids, as found by the analysis of Tschopp & Mateus (2017). [2]

  Diplodocidae  
  Apatosaurinae  

Apatosaurus ajax

Apatosaurus louisae

Brontosaurus excelsus

Amphicoelias altus

Brontosaurus yahnahpin

Brontosaurus parvus

  Diplodocinae  

Kaatedocus siberi

Tornieria africana

Dinheirosaurus lourinhanensis

Supersaurus vivianae

Leinkupal laticauda

Galeamopus hayi

Galeamopus pabsti

Barosaurus lentus

Diplodocus carnegii

Diplodocus hallorum

See also

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>Supersaurus</i> Extinct genus of dinosaurs

Supersaurus is a genus of diplodocid sauropod dinosaur that lived in North America during the Late Jurassic period. The type species, S. vivianae, was first discovered by Vivian Jones of Delta, Colorado, in the middle Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating between 153 to 145 million years ago. It was a very large sauropod, with the WDC and BYU specimens reaching 33–35 metres (108–115 ft) in length and approximately 35–40 metric tons in body mass. A potential second species, S. lourinhanensis, (Dinheirosaurus) is known from Portugal and has been dated to a similar time.

<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.

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

Hesperosaurus is a herbivorous stegosaurian dinosaur from the Kimmeridgian age of the Jurassic period, approximately 156 million years ago.

<i>Barosaurus</i> Diplodocid sauropod dinosaur genus from Upper Jurassic Period

Barosaurus was a giant, long-tailed, long-necked, plant-eating sauropod dinosaur closely related to the more familiar Diplodocus. Remains have been found in the Morrison Formation from the Upper Jurassic Period of Utah and South Dakota. It is present in stratigraphic zones 2–5.

<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.

<i>Brontosaurus</i> Genus of diplodocid sauropod dinosaur

Brontosaurus is a genus of herbivorous sauropod dinosaur that lived in present-day United States during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed B. excelsus, based on a partial skeleton lacking a skull found in Como Bluff, Wyoming. In subsequent years, two more species of Brontosaurus were named: B. parvus in 1902 and B. yahnahpin in 1994. Brontosaurus lived about 156 to 146 million years ago (mya) during the Kimmeridgian and Tithonian ages in the Morrison Formation of what is now Utah and Wyoming. For decades, the animal was thought to have been a taxonomic synonym of its close relative Apatosaurus, but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct. It has seen widespread representation in popular culture, being the archetypal "long-necked" dinosaur in general media.

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

Camarasaurus lewisi is a species of sauropod dinosaur from the Upper Jurassic of the United States. It was named by James A. Jensen in 1988. C. lewisi was originally placed in its own genus, Cathetosaurus, but in 1996 it was reclassified as a species of Camarasaurus; most researchers since have considered it to be one of the four valid species of Camarasaurus. Two unpublished studies have since argued that the genus Cathetosaurus should be reinstated, whereas two other studies have argued that C. lewisi may be a junior synonym of another species of Camarasaurus.

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

Dinheirosaurus is a genus of diplodocid sauropod dinosaur that is known from fossils uncovered in modern-day Portugal. It may represent a species of Supersaurus. The only species is Dinheirosaurus lourinhanensis, first described by José Bonaparte and Octávio Mateus in 1999 for vertebrae and some other material from the Lourinhã Formation. Although the precise age of the formation is not known, it can be dated around the early Tithonian of the Late Jurassic.

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

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

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

Camarasaurus lentus is an extinct species of sauropod dinosaur that lived during the Jurassic period in what is now the western United States. It is one of the four valid species of the well-known genus Camarasaurus. C. lentus fossils have been found in Wyoming, Colorado, and Utah. It is the species of Camarasaurus found in Dinosaur National Monument and the middle layers of the Morrison Formation. Camarasaurus lentus is among the best-known sauropod species, with many specimens known. A juvenile specimen of C. lentus, CM 11338, is the most complete sauropod fossil ever discovered.

<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 was a genus of diplodocid sauropod dinosaurs, whose fossils were first 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.

<i>Brachiosaurus</i> Sauropod dinosaur genus from the late Jurassic Period

Brachiosaurus is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154 to 150 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between 18 and 22 meters long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons. It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, Brachiosaurus had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk, and a proportionally shorter tail.

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

Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe, Africa and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, and Barosaurus.

<i>Kaatedocus</i> Extinct genus of reptiles

Kaatedocus is a genus of flagellicaudatan sauropod known from the middle Late Jurassic of northern Wyoming, United States. It is known from well-preserved skull and cervical vertebrae which were collected in the lower part of the Morrison Formation. The type and only species is Kaatedocus siberi, described in 2012 by Emanuel Tschopp and Octávio Mateus.

<i>Leinkupal</i> Extinct genus of reptiles

Leinkupal is a genus of diplodocine sauropod known from the Early Cretaceous of the Bajada Colorada Formation, southeastern Neuquén Basin in the Neuquén Province of Argentina. It contains a single species, Leinkupal laticauda.

<span class="mw-page-title-main">Dippy</span> Diplodocus fossil

Dippy is a composite Diplodocus skeleton in Pittsburgh's Carnegie Museum of Natural History, and the holotype of the species Diplodocus carnegii. It is considered the most famous single dinosaur skeleton in the world, due to the numerous plaster casts donated by Andrew Carnegie to several major museums around the world at the beginning of the 20th century.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Tschopp, E.; Mateus, O. V.; 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.
  2. 1 2 3 4 5 6 7 Emanuel Tschopp; Octávio Mateus (2017). "Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids". PeerJ. 5: e3179. doi: 10.7717/peerj.3179 . PMC   5417106 . PMID   28480132.
  3. 1 2 3 Holland WJ. The skull of Diplodocus. Memoirs of the Carnegie Museum IX; 379–403 (1924).
  4. Holland, W.J. (1906). "The osteology of Diplodocus Marsh". Memoirs of the Carnegie Museum. 2: 225–264.