Mines Research Reveals New Findings on One of the Earliest Iguanodont Dinosaurs of North America
RAPID CITY, S.D. (Sept. 24, 2015) – New research published by paleontolo- gists at the South Dakota School of Mines & Technology reveals an herbivorous dinosaur from the Black Hills as more than 20 million years older than previ- ously thought.
Findings published this week in the online journal PeerJ are significant because they could help piece together the evolutionary picture of the Dakotadon lakotaensis and its descendants.
New research by South Dakota Mines paleontologist Darrin Pagnac, Ph.D., and Clint Boyd, Ph.D., former Mines paleontol- ogist now employed with the North Dakota
Geological Survey, determined the dinosaur is between 135 million and 127 million years old, putting it in the geologic age of the early Cretaceous period, making it one of the earliest types of such dinosaurs known from North America.
The fossil housed at the university is the only Dakotadon lakotaensis specimen known to exist.
Dakotadon lakotaensis is an iguanodont, a type of herbivo- rous dinosaur that lived throughout the northern hemisphere in the early Cretaceous period. Iguanodonts are characterized by an elongate, horse-like skull, robust hind limbs and short- ened forelimbs with an immobile “spike” in place of a thumb.
The specimen was donated to the university’s Museum of Geology in the mid 1970s after Louis Rossow discovered it on his property east of Whitewood in an outcropping of the Lower Cretaceous Lakota Formation. In 1989, it was described as Iguanodon lakotaensis in a paper by David Weishampel and Philip Bjork, former Museum of Geology director. Subsequent work in 2008 revealed it to be a new genus, hence the new name Dakotadon.
The original site of excavation was relocated in 2014 with the aid of Rossow’s grandchildren. Relocation of the site helped Pagnac and Boyd determine the precise age of the specimen.
At the Paleontology Research Laboratory on campus, then preparator Mindy Householder conducted additional prepa- ration and conservation, revealing new anatomy and other information not included in the original description.
Householder’s work exposed several new bones not included in the original description and revealed some bones that were previously misidentified. Extensive deformation due to fos- silization processes in areas of the skull was also noted that
Late evening view, looking south across Moldefjord from Ottroy, an island on the Atlantic coast. The rosy summits rise to an elevation of about 1000 meters above the very nearby sea
level.Photo from Kurt Hollocher, Union College.
influenced inaccuracies in prior descriptions and reconstruc- tions, according to Pagnac and Boyd.
“Mr. Rossow discovered an exceedingly important speci- men, the only of its type known worldwide. The cranial anatomy of Dakotadon is revealing a great deal about the evolution of these herbivorous dinosaurs between the late Jurassic and early Cretaceous periods,” said Pagnac.
Traveling Geologist Photo Below
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