Ceratopsian Dinosaurs are thought to have originated in Asia in the
Early Cretaceous, spreading to Europe and North America, and becoming the most
important and diverse group of herbivorous Dinosaurs in North America by the
end of the Period. Unfortunately, while the group are well known from Latest
Cretaceous fossils in North America, for much of the period they are only known
from isolated teeth and bone fragments. It is not certain when they first
reached North America, nor whether they got their via northeast Asia and Alaska
or via Europe.
In a paper published in the journal PLoS One on 10 December 2014,
Andrew Farke of the Raymond M. Alf Museum of Paleontology and the Sam Noble Oklahoma Museum of Natural History, Desmond Maxwell of the Department of Biological Sciences at the University of the Pacific and the Sam Noble Oklahoma
Museum of Natural History, Richard Cifellialso of the Sam Noble Oklahoma Museum
of Natural History and Mathew Wedel of the College of Podiatric Medicine at the
Western University of Health Sciences and of the Sam Noble Oklahoma Museum of
Natural History describe a new species of Ceratopsid Dinosaur from the Early
Cretaceous Cloverly Formation of Carbon County in southern Montana.
The new species is named Aquilops americanus,
where ‘Aquilops’ means ‘Eagle-face’,
a reference to the Dinosaur’s hoked beak, and ‘americanus’ means ‘American’. The specimen comprises a partial
skull 84.2 mm in length, with an accompanying left lower jaw in three
fragments. The skull is slightly compressed mediolaterally and dorsoventrally,
leading to some deformation, particularly at the rear, and the right side is
better preserved than the left.
Cranium of Aquilops americanus. (A)
Right lateral and (B) left lateral views. Farke et al. (2014).
Aquilops americanusis about 60% of the size of specimens of the early Ceratopsians Liaoceratops yanzigouensis and Archaeoceratops oshimai, both of which
are presumed to be adults, and pf a similar size to a presumed juvenile
specimen of Liaoceratops yanzigouensis.
Developmentally it shows a mixture of features associated with juvenile and
adult Ceratpsians, and Farke et al. suggest
that the specimen is a subadult (i.e. an animal that had almost reached adult
size).
Cranial reconstruction of Aquilops americanus in (A) right lateral and (B) dorsal views. Farke et al. (2014).
Aquilops americanus is the earliest described Ceratopsian from North America, dating
from about 104–109 million years ago. This suggests that Ceratopsians had
reached the continent much earlier than previously supposed; however as we
currently understand the phylogeny of Ceratpsian Dinosaurs it occupies a
position very close to the base of the group’s family tree, with the more
derived Ceratopsians of Late Cretaceous North America emerging from a group of
Dinosaurs that were apparently still in Asia much later the period, suggesting
that Aquilops americanus is the result
of an earlier, separate invasion of the continent, and has little bearing on
the origins of these later animals.
Hypothesis of phylogeny and biogeography for
Neoceratopsia. Some terminal taxa have been combined for space considerations,
and the range bars for each taxon indicate uncertainty rather than known
geological ranges. Continent icons indicate the ancestral areas reconstructed
by DEC modeling. Silhouettes depict representative members of major clades and
grades. Farke et al. (2014).
Life restoration of Aquilops americanus. Brian Engh in Farke et al. (2014).
See also…
Ceratopsid Dinosaurs were a speciose group of large, herbivorous
Dinosaurs from the Late Cretaceous of...
Ceratopsid Dinosaurs were a speciose group of large, herbivorous
Dinosaurs from the Late Cretaceous of Asia and North America. They were
large, quadruped Dinosaurs with distinctive neck-frills and horns, and...
Ceratopsid dinosaurs changed considerably during growth, which caused
early palaeontologists to name different growth stages of the same
animal as different species, or even genera. The Maastrichtian (Latest
Cretaceous, 70.6-65.5 million years ago) Ceratopsids of North America
were at one point divided into 22 species...
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