Ugrunaaluk
Name:
Ugrunaaluk
(Ancient grazer).
Phonetic: Ug-ru-naa-luk.
Named By: Hirotsugu Mori, Patrick S.
Druckenmiller & Gregory M. Erickson - 2015.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Hadrosauridae, Saurolophinae, Edmontosaurini.
Species: U. kuukpikensis
(type).
Diet: Herbivore.
Size: Roughly about 10 meters long.
Known locations: USA, Alaska - Prince Creek
Formation.
Time period: Early Maastrichtian of the Cretaceous.
Fossil representation: Remains of many individuals.
Since
the closing decades of the twentieth century literally thousands of
fossil bones of hadrosaurid
dinosaurs have been found in Alaska.
Initially considered to be lambeosaurines (the type with bony head
crests), there were later determined to be saurolophines,
specifically similar to Edmontosaurus.
Most of these remains however
have come from juveniles which has made it awkward to identify a
specific genus given that juveniles can change form as they grow up.
Still, work that began in 2014 has concluded with the
establishment of a new genus for some of these remains in 2015, and
that genus is Ugrunaaluk.
Ugrunaaluk
was one of the most northern living hadrosaurs that we currently know
about, and grew to a fairly large size. This places Ugrunaaluk
in
good standing to its more immediate relative genera such as
Edmontosaurus as well as the particularly large
Shantungosaurus
from
China. As with other hadrosaurs Ugrunaaluk would
have been a plant
eater and primarily quadrupedal when walking about, though bipedal
locomotion and rearing would have still been possible, and perhaps
quite common when feeding. Like other saurolophines, Ugrunaaluk
had
no kind of bony head crest. However, soft tissue preservation and
studies in Edmontosaurus have proven that in life Edmontosaurus
regalis
had a fleshy soft tissue crest-like growth on its head. It is unknown
if Ugrunaaluk had a similar display device.
One
thing that stood out about the naming of Ugrunaaluk
in 2015 is the
surprise that most people still had at hearing the news that a dinosaur
had been discovered in what is now Alaska. For a start it must be
remembered that while in the Cretaceous Alaska was cooler that the
tropical latitudes, it was still much warmer than it was today. In
addition to this, many dinosaurs have been found in Alaska before
Ugrunaaluk was. These include ceratopsians
such as Pachyrhinosaurus,
pachycephalosaurs
such as Alaskacephale
as well as indeterminate
remains of small ornithopods. Predatory dinosaurs such as
dromaeosaurs
and troodonts
such as Dromaeosaurus,
Saurornitholestes,
and even a variety of Troodon
larger than southern relatives are also
known. To top all this off there is even a tyrannosaur
named
Nanuqsaurus
known from the same formation as Ugrunaaluk,
and this
predator may have been a particular danger to Ugrunaaluk.
Further reading
- Dinosaurs on the North Slope, Alaska: High latitude, latest
Cretaceous environments. - Science 237: 1608–1610. - E.
M. Brouwers, W. A. Clemens, R. A. Spicer, T. A.
Ager, L. D. Carter & W. V. Sliter - 1987.
- Comparative Osteology and Phylogenetic Relationship of
Edmontosaurus and Shantungosaurus
(Dinosauria: Hadrosauridae)
from the Upper Cretaceous of North America and East Asia. - Acta
Geologica Sinica 88: 1623–1652. - H. Xing, X. Zhao,
K. Wang, D. Li, S. Chen, C. M. Jordan, Y. Zhang
& X. Xu - 2014.
- Osteology, Relationships And Paleoecology Of a New Arctic
Hadrosaurid (Dinosauria: Ornithopoda) From the Prince Creek
Formation Of Northern Alaska. Unpublished Ph.D. thesis -
University of Alaska Fairbanks, Fairbanks 333 pp - Hirotsugu
Mori - 2014.
- A new Arctic hadrosaurid from the Prince Creek Formation (lower
Maastrichtian) of northern Alaska. - Acta Palaeontologica
Polonica. - Hirotsugu Mori, Patrick S. Druckenmiller &
Gregory M. Erickson - 2015.
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