Gastonia (Gaston’s thing)

Short Info

Gastonia (Gaston's thing)

Phonetic : Gas-toe-nee-ah.

Named By : James Kirkland – 1998

Diet : Herbivore

Size : Estimated 5 meters long

Type of Dinosaur : Armoured Dinosaur

Type Species : G. burgei (type). G. lorriemcwhinneyae

Found in : USA, Utah – Cedar Mountain Formation

When it Lived : Early Cretaceous, 142-127 million years ago

Gastonia is a genus that includes herbivorous ankylosaurian dinos from the Early Cretaceous period of North America. It dates back to around 139 million to 125million years ago. It is closely related to Polacanthus and is sometimes considered a nodosaurid. Gastonia is distinguished by its large shoulder spikes and a sacral shield.

Gastonia mount BYU 4Etemenanki3, CC BY-SA 4.0, via Wikimedia Commons

The type Gastonia burgei specimen (CEUM 1307) was found in a bonebed from the Cedar Mountain Formation, Grand County, Utah. It contained fossil remains of Gastonia burgei, an iguanodontid, and the type specimen Utahraptor, a large carnivorous dinosaur. Gastonia is one of the most well-known dinosaur fossils from the Cedar Mountain Formation. James Kirkland officially named Gastonia and gave it a description in 1998. He used the holotype specimen as well as other fossil material that was found beginning in 1989. Gastonia is named after Robert Gaston, a US Palaeontologist. Donald L. Burge, director of College of Eastern Utah Prehistoric Museum was the inspiration for the species G. burgei.

Gastonia burgei was discovered in the Cedar Mountain Formation’s Yellow Cat Member. It has been dated back to the Valanginian (139 to 134.6 Million years ago). CEUM 1307 is the holotype, which is a skull from an adult. A number of hundreds more disarticulated bones were also found in the Gaston Quarry and Dalton Wells Dinosaur Quarry [nl]. These bones included the remains of at most five people in 1998. In 2004, there were four skulls. By 2014, it had increased to ten.

Gastonia fossilGreg Goebel from Loveland CO, USA, CC BY-SA 2.0, via Wikimedia Commons

G. lorriemcwhinneyae was a second species that was discovered in the Ruby Ranch Member. It is based on a large bonebed which formed after a group of people died from drought or drowning.

Gastonia has more complete material than any other basal ankylosaur. [6] It can be difficult to determine how many spikes a Gastonia actually had because of the abundance of bonebed material.

A skeleton was built from polyurethane castings of the skeletal elements of different individuals in the latter part of twentieth century. The fossils were reconstructed and corrected for any distortions. Gastonia was the first basal ankylosaurian dinosaur that was mounted at the Denver Museum of Nature and Science. It also exhibited with the Gargoyleosaurus.

Gastonia was a medium-sized ankylosaur. Kirkland put its length at six meters in 1998. Gregory S. Paul stated a length of five meters and a weight in 2010 of 1.9 tonnes. The skeleton mount measures 459 cm in length and 112 cm high at the hips.

Because Gastonia’s affinities are not known, it is difficult to identify distinguishing traits. Kirkland created three characters in 1998 that were unique to the Ankylosauria. These characters are likely autapomorphies or unique derived traits. The bony core of an upper horny, or upper horny, beak is located at the midline of the front. A broad, slowly curved notch is found between the snout bones and the praemaxillae. The bony nostrils can be found further back. The basipterygoid process is longitudinally stretched at the basephenoid of the braincase.

Gastonia was a very flat, and even for an anylosaurian it had a large rump. The belly protruded between the powerful, short limbs. The tail was mediumly long, and did not have a tail club. The skull was probably quite small and the neck was long.

The skull measures 295 by 283 mm in the holotype. It is slightly elongated, and pointed. The skull’s top profile is convex. The rear skull roof curves below the level of eye sockets’ upper rims. The quadrate is strongly inclined towards the rear. The contact with the neck is the occipital conedyle. This ankylosaurid trait causes the head to point downwards. The beak is toothless. The maxillae’s tooth rows are quite straight. They each have fifteen to sixteen small, non-cingulum teeth. The snout is not covered with armour. The skull roof’s bony tiles, or caputegulae as they are called, are not clearly patterned. However, a small central plate is visible on the parietal bone. The cheeks have small squamosal and jugal skull corners horns.

The sacrum is composed of three sacral vertebrae and a caudosacral vertebra. There are no stiffened rear tail vertebrae, or tail clubs. Although the shoulder blade is similar to that of nodosaurids, it has an acromion that is similar to that of nodosaurids. It does not have a wrap to the back and ends in a knob. This is not a typical “pseudoacromion” nodosaurid. The coracoid’s shape is typical ankylosaurid. A derived trait is the large deltopectoral crown that extends downwards from the shaft to the humerus. The ulna has a very strong olecranon. Both the upper and lower ends of the shinbone are very broad.

Gastonia was protected with osteoderms and skin ossifications. At least two bone rings covered the neck. These bone rings are usually called “halfrings” in ankylosaurs, leaving the underside exposed. However, Gastonia has only two segments, one on each side of the midline. Kirkland refers to them as “quarter ring”. Each segment had a pointed, hollow underside and a keel. Kirkland stated that it was difficult to reconstruct the rump armor because it was not found in articulation. Five pairs of flat triangular flat spikes covered the sides of Kirkland’s thorax. They are recurved with a deep groove on the rear. As they decrease in length, the groove becomes shorter and the base gets longer. Kirkland stated that the groove’s purpose was to receive the spike’s front edge. The groove was absent from other large flat spikes. These spikes were often very curvy, with the point at an angle to the base. Kirkland believed that these were two vertical rows of spikes, one on each side the rump’s midline. He placed lower triangular spikes at the tail’s sides, and they gradually decreased to the rear. Between the vertical and horizontal spikes on the rump, there were likely rows of osteoderms with the profile of droplets. The vertical end had a wider point than the other. Oval plates covered the top of the tail. A large pelvic shield made of fused osteoderms covered the hip area. These rosettes were patterned in the form of rosettes, with a larger central plate and at least two rings of smaller plates. Kirkland believed that the pelvic shield was covered by four pairs of triangular spikes, but Paul denied this. Small ossicles were small bony scutes that covered the area between these larger elements. There have been hundreds of them.

G. lorriemcwhinneyae is different from G. burgei because it has a flat skull roof and shorter paroccipital process. It also has a 36% shorter postacetabular processes and an ischium with a smooth, unkinked bottom edge.

Source: Wikipedia