Aquilops

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Aquilops
Temporal range: Early Cretaceous, 107  Ma
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Aquilops americanus.png
Skull seen from the sides, above, and below
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Suborder: Ceratopsia
Infraorder: Neoceratopsia
Genus: Aquilops
Farke et al., 2014
Species:
A. americanus
Binomial name
Aquilops americanus
Farke et al., 2014

Aquilops is an early herbivorous ceratopsian dinosaur dating from the Early Cretaceous of North America, approximately 109 million to 104 million years ago. The type species is A. americanus.

Contents

Description

Restoration Aquilops.png
Restoration

The skull is 84.2 mm long. The holotype is possibly not from a full-grown individual. A comparison with related species indicates it might have been at 60% of its adult length. [1] Wedel estimated the total body length of Aquilops at 60 cm and its weight at 1.5 kg. [1]

The authors established some unique traits. The rostral, the bone core of the snout beak, curves downwards and has an arched keel on its top with a bump on the front. In front of the tooth row the upper jaw rim is over its total length concave in side view. The skull opening, the antorbital fenestra, is twice as long as it is tall and has a pointed rear, below the eye socket. [1]

Discovery and naming

Restored skull Aquilops skull.png
Restored skull

In 1997, paleontologist Scott Madsen found the single fossil, a partial skull, in Carbon County in southern Montana. While preparing the specimen, at first assumed to be of Zephyrosaurus , he discovered that it was a species new to science. [2]

In 2014 the type species Aquilops americanus was named and described by Andrew Farke, W. Desmond Maxwell, Richard L. Cifelli, and Matt J. Wedel. The generic name is derived from Latin aquila, "eagle", and Greek ὤψ, ops, "face", in reference to the beaked snout. The specific name americanus refers to the fact that the species represents the first unequivocal very basal neoceratopsian found in America. [1]

The holotype, OMNH 34557, was found in a layer of the Cloverly Formation, dating from the middle-late Albian. It consists of a skull with lower jaws, of a subadult individual. The rear of the head and the palate are the main lacking parts. [1] The specimen was found during a 1997 expedition supported by the National Geographic Society and directed by Cifelli.

Classification

Lower jaw Aquilops jaw.png
Lower jaw
Cloverly formation environment with Gobiconodon pursuing juvenile Aquilops while adults attempt to protect them. Aquilops americanus restoration.jpg
Cloverly formation environment with Gobiconodon pursuing juvenile Aquilops while adults attempt to protect them.
3D scan of the holotype cranium (click thumbnail to turn around) Aquilops cranium scan.stl
3D scan of the holotype cranium (click thumbnail to turn around)

Aquilops was placed in the Neoceratopsia. A cladistic analysis showed that it was positioned rather basal, below Leptoceratops in the evolutionary tree, with only Liaoceratops being more basal. A more derived position, e.g. as a leptoceratopsid or a protoceratopsid, was less likely; it was improbable that it was a ceratopsoid. The fact that the holotype was a subadult might have distorted these results because juvenile individuals often show basal traits. However, after correcting for traits that might change during ontogeny, the resulting tree was basically the same. The ceratopsians more derived than psittacosaurids, called neoceratopsians, evolved in Asia: the presence of a basal neoceratopsian in North America was seen as an indication for a late Early Cretaceous migration event, the ancestors of Aquilops invading from Asia. Two later such events would have occurred in the early Late Cretaceous. [1]

Marginocephalia
Pachycephalosauria

Stegoceras

Ceratopsia

Yinlong

Xuanhuaceratops

Chaoyangsaurus

Psittacosaurus

P. sinensis

P. mongoliensis

Neoceratopsia

Liaoceratops

Aquilops

Auroraceratops

Yamaceratops

Helioceratops

Archaeoceratops

Koreaceratops

Leptoceratopsidae

Coronosauria

See also

Related Research Articles

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

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Timeline of ceratopsian research

This timeline of ceratopsian research is a chronological listing of events in the history of paleontology focused on the ceratopsians, a group of herbivorous marginocephalian dinosaurs that evolved parrot-like beaks, bony frills, and, later, spectacular horns. The first scientifically documented ceratopsian fossils were described by Edward Drinker Cope starting in the 1870s; however, the remains were poorly preserved and their true nature was not recognized. Over the next several decades, Cope named several such genera and species. Cope's hated rival, Othniel Charles Marsh, also described ceratopsian remains. In 1887, Marsh mistook a Triceratops horn for one belonging to a new species of prehistoric Bison. Marsh also named the eponymous genus Ceratops in 1888. The next year, he named the most famous ceratopsian, Triceratops horridus. It was the discovery of Triceratops that illuminated the ceratopsian body plan, and he formally named the Ceratopsia in 1890.

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

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References

  1. 1 2 3 4 5 6 Farke, Andrew A.; Maxwell, W. Desmond; Cifelli, Richard L.; Wedel, Mathew J. (2014-12-10). "A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia". PLoS ONE . 9 (12): e112055. Bibcode:2014PLoSO...9k2055F. doi: 10.1371/journal.pone.0112055 . PMC   4262212 . PMID   25494182.
  2. Crofts, Natalie (2014-12-12). "Utah paleontologist shares tale of discovering cat-sized dinosaur". KSL.com. Salt Lake City: Deseret Digital Media . Retrieved 2014-12-23.