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Alamosaurus ‭(‬Alamo lizard‭)‬

Alamosaurus ‭(‬Alamo lizard‭)‬


Named By

Charles W.‭ ‬Gilmore‭ ‬-‭ ‬1922




Estimated 20-24 meters long

Type of Dinosaur


Type Species

A.‭ ‬sanjuanensis‭ (‬type‭)

Found in

USA,‭ ‬New Mexico‭ ‬-‭ ‬Ojo Alamo Formation‭ (‬possibly part of the Kirtland Formation,‭ ‬Utah‭ ‬-‭ ‬North Horn Formation and Texas‭ ‬-‭ ‬Black Peaks Formation,‭ ‬El Picacho Formation and Javelina Formation.

When it Lived

Early Jurassic, 199-189 million years ago

Alamosaurus Facts

Alamosaurus (/,ael@moU'so:r@sor “Ojo Alamo lizard”) is an opisthocoelicaudiine genus from the late Cretaceous Period of what is today the southern part of North America. It is comprised of only one known species, Alamosaurus sanjuanensis, from the Maastrichtian time period of the Cretaceous's late period.

It was a huge herbivore quadrupedal with an extended neck and tail, and large legs. Thomas Holtz estimated a total length of 30 meters (98 feet) or more, and an estimated mass in the range of 72.5-80 tons (80-88 small ton). 3 fragmentary specimens SMP 1625 and VP-1625 indicate that an adult Alamosaurus might be growing to huge dimensions comparable to the biggest known dinosaurs such as Argentinosaurus.

Scott Hartman estimates Alamosaurus, from a massive incomplete tibia, as being somewhat smaller at 28-30 meters (92-98 feet). Gregory S. Paul estimated the specimen to be 27 tons (30 short tons) and identified a massive partially anterior caudal vertebra. Molina-Perez and Larramendi determined the dimensions of the largest specimen with a height of 26 metres (85.3 feet) in weight and 38 tonnes (42 short tons). No skull has been discovered, but rod-shaped teeth were found in Alamosaurus Skeletons. Alamosaurus had vertebral fossae lateral to its vertebrae which looked like shallow depressions.

Venenosaurus also had depression-like fossae, but they split into two chambers and extended deeper into the vertebral columns. Alamosaurus also had larger radius as compared to Venenosaurus.

Alamosaurus remains are found across the southwestern United States, with the holotype being found in 1921 by Charles Whitney Gilmore, John Bernard Reeside and Charles Hazelius Sternberg at the Barrel Springs Arroyo in the Naashoibito Member of the Ojo Alamo Formation (or Kirtland Formation with a different meaning). Bones have also been found from different Maastrichtian formations, such as that of North Horn Formation of Utah as well as in the Black Peaks, El Picacho and Javelina Formations in Texas.

Three articulated caudal vertebrae were found in the area of Hams Fork, and are kept in the Museum of Paleontology, University of California, Berkeley. Gilmore first identified the holotype, USNM 1046, a left scapula (shoulder bone) as well as its Paratype USNM 10487, which is a right ischium (pelvic bone) in 1922, and named the species of type Alamosaurus sanjuanensis. Contrary to popular belief, the dinosaur was not named in honor of it's home, the Alamo located in San Antonio, Texas, or the battle that was fought there.

Instead, the name Alamosaurus originates in the form of the geologic formation that it was discovered, and was later named for Ojo alamo, a nearby trading post. The term saurus originates by saura (saura), Greek for “lizard” and is the most commonly used suffix in dinosaur names. There is just one species in the genus.

In 1946, Gilmore postedhumously reported a complete and extensive specimen of USNM 15660, discovered on the 15th of June in 1937 at the North Horn Mountain of Utah by George B. Pearce. Since then, a myriad of fragments and pieces of Texas, New Mexico, and Utah have been identified as Alamosaurus and often with no details.

The most widely known piece, TMM 43621-1, is the most recent discovery of a juvenile skeleton found in Texas that allowed for educated estimations of the length and mass. Michael Brett-Surman revealed that the blocks had osteoderms, which was the first evidence of their presence on Alamosaurus. There is no skull material to be found with the exception of some slender teeth.

Gilmore was unsure regarding the exact affinities between Alamosaurus and was unable to find it more than an overall Sauropoda. Friedrich von Huene placed it within the Titanosauridae, but its connections within the group aren't always clear. Other scientists have also noticed certain similarities between those of the Saltasauridae and Alamosaurus.

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