Alamosaurus

Alamosaurus was named for Alamo Creek, San Juan Basin, New Mexico, where the first specimen was discovered. Alamosaurus roamed over much of southwestern North America during the latest part of the Cretaceous. It became extinct at the very end of the Mesozoic Era, during the mass extinction episode that wiped out many other species at the same time. Alamosaurus was one of the very last of the non-avian dinosaurs in Texas.
Alamosaurus was a member of the sauropod dinosaur lineage. The sauropods were not only the largest dinosaurs but also the largest land animals ever to evolve. Only some of today’s baleen whales are larger. The largest sauropods may have weighed around 50 tons. This is about 10 times more than African elephants, who are the largest land-living animals alive today.
The earliest members of the lineage were small and walked on their hind legs, leaving their hands free for other purposes. But during the course of the Mesozoic, the sauropods evolved to giant size, and had to drop to all fours in order to support their gigantic weight. At the same time, they evolved almost unbelievably long necks but retained relatively small heads. Of all the dinosaurs, they had the smallest brains compared to their body size.
Alamosaurus and the other huge sauropods were herbivores. They had small blunt teeth, which they used for cropping and stripping vegetation. The discovery of polished stones inside the ribcage in several skeletons suggests that they had a large muscular gizzard containing stones to mechanically break down fibrous plants. The stones accomplished the grinding of food instead of the teeth!
The two huge bones of Alamosaurus buried in the Dino Pit were cast from specimens collected from Big Bend National Park in 1971 and 1973 by Dr. Wann Langston, Jr. and a crew from the Vertebrate Paleontology Laboratory of the Texas Natural Science Center. One bone is the humerus (upper arm bone), which lies between the shoulder and elbow joints. The other is the femur (thigh bone), which extends from the hip to the knee joint. These two bones came from different individuals of about the same size.
Alamosaurus is a genus of titanosaurian sauropod dinosaur from the Early Cretaceous Period of North America. It was a large quadrupedal herbivore, up to 53 feet (16 meters) in length and up to 33 tons (30 metric tonnes) in weight. Alamosaurus, like other sauropods, had a long neck and tail, which may have ended in a whiplash structure.
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Etymology
Contrary to popular assertions, this dinosaur is not named after the Alamo in San Antonio, Texas, or the battle fought there. The holotype, or original specimen, was discovered in New Mexico, and at the time of its naming, no remains of Alamosaurus had been found in Texas. Instead, the name Alamosaurus comes from Ojo Alamo, the former name for the formation it was found in, which in turn was named after the nearby Ojo Alamo trading post. The term alamo itself is a Spanish word meaning "poplar" and is used for the local subspecies of cottonwood tree. The term sauros is Greek for "lizard" and is the most common suffix used in dinosaur names.
There is one named species (A. sanjuanensis). It is named after San Juan County, New Mexico, where the first remains were found.
Both genus and species were named by Smithsonian paleontologist Charles. W. Gilmore in 1922.

Location and Age
Alamosaurus remains have been discovered throughout the southwestern United States. The holotype was discovered in the Lower Kirtland Formation of New Mexico, and since then, Alamosaurus has also been found in the upper part of the Kirtland, a formation which was deposited during the Maastrichtian stage of the Late Cretaceous Period. Bones have also been recovered from other Maastrichtian formations, like the North Horn Formation of Utah, and the Black Peaks, El Picacho, and Javelina Formations of Texas. These formations start around 74 million years ago and last right up to the end of the Cretaceous, 65 million years ago. Alamosaurus may have been one of the last dinosaurs to go extinct.
Skeletal elements of Alamosaurus are among the most common Late Cretaceous dinosaur fossils found in the American Southwest and are now used to define the fauna of that time and place. Other contemporaneous dinosaurs from that part of the world include tyrannosaurs, smaller theropods, Nodocephalosaurus, Parasaurolophus, Torosaurus, and Pentaceratops, among others.

Remains
Gilmore originally descibed a scapula and ischium in 1922. In 1946, he found a more complete specimen in Utah, consisting of a complete tail, a right forelimb complete except for the tips of the toes, and both ischia. Since then, many other bits and pieces from Texas, New Mexico, and Utah have been referred to Alamosaurus without much description. Lehman & Coulson (2002) describe the most completely known specimen, a juvenile skeleton from Texas, which allowed them to make educated estimates of length and mass.
No skull material is known except for a few slender teeth, and no armor scutes have been reported, such as those found in other advanced titanosaurians like Saltasaurus.

Relationships
Alamosaurus is undoubtedly a derived member of Titanosauria, but relationships within that group are far from certain. Wilson (2002) unites Alamosaurus with Opisthocoelicaudia in a subfamily Opisthocoelicaudinae of the family Saltasauridae. The major competing analysis, performed by Upchurch et al. (2004), finds Alamosaurus as a sister taxon to Pelligrinisaurus, with both genera located just outside Saltasauridae.
Lehman & Coulson (2002) do not perform a phylogenetic analysis, but note similarities between the saltasaurid Neuquensaurus and the as-yet-unnamed Brazilian "Peiropolis titanosaur" which is used in many cladistic and morphologic analyses of titanosaurians.