Episode 51 is all about Alamosaurus, the only known sauropod to live in the Cretaceous in what is now North America.

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In this episode, we discuss:

• The dinosaur of the day: Alamosaurus
• Name means “Ojo Alamo lizard”
• Only one species: Alamosaurus sanjuanensis
• Holotype found in June 1921, by Charles Gilmore, John Reeside and Charles Sternberg in the Ojo Alamo Formation of New Mexico (some call it the Kirtland Formation); other bones since found in Utah and Texas (juvenile found in Texas)
• Gilmore described the species in 1922 and named it (NOT named after the Alamo in San Antonio, Texas, or after the battle there); when it was named, Alamosaurus bones had not yet been found in Texas
• Name comes from Ojo Alamo, the geologic formation where the bones were found (which was named after the Ojo Alamo trading post); some debate though over whether to reclassify the area as the Kirtland Formation or stay the Ojo Alamo Formation
• In Spanish the word alamo means “poplar”, which is the local cottonwood tree
• Sanjuanensis is named after San Juan County, New Mexico where the bones were found
• Gilmore posthumously described a more complete Alamosaurus in 1946, that was found in 1937 (in Utah, by George Pearce); found a complete tail, right forelimb (no fingers)
• Since then, hundreds of pieces of fossils found in Texas, New Mexico and Utah have been referred to as Alamosaurus
• Fossils have been found of a juvenile and three fragmentary specimens
• Not any really complete specimens have been found (tends to be more common to find juveniles because sediment covers smaller bodies more easily)
• Most complete specimen is the juvenile found in Texas
• Bits of Alamosaurus skeletons are some of the most common finds of late Cretaceous fossils in the southwest of the U.S., and are used to help define the fauna from then, called the “Alamosaurus fauna”
• Found vertebrae and limb bones, which show it was around the same size as Argentinosaurus and Puertasaurus (may be the largest known dinosaur in North America); may have weighed as much as 73 tons
• Dana Biasetti, a grad student from the University of Texas in Dallas, found pelvic bones and ten articulated cervical vertebrae of an adult Alamosaurus in 1999 in the Javelina Formation of Big Bend National Park (“Big Bend Alamosaurus“); may have been up to 100 ft long and weighing over 50 tons
• Before, estimate was about 65 ft or 20 m long (based on juvenile skeleton and partial adult skeletons)
• The bones were so large and the area so remote that Big Bend National Park issued a permit to remove the bones via helicopter, and in 2001 it was the first “dinosaur airlift”
• Holly Woodward in 2009 found that the femur of an Alamosaurus bone was still growing, so researchers knew it got bigger
• Alamosaurus lived in the Cretaceous in North America
• There’s a 30 million year gap where sauropods seem to have died out in North America and when Alamosaurus appeared
• Sauropods seem to have been more common at the end of the Jurassic (instead of Cretaceous); but could be we just haven’t found the fossils of more sauropods yet (some sauropods from the Cretaceous in North America include Astrodon, Sauroposeidon and Cedarosaurus
• Alamosaurus may prove immigration from South America (appears and is dominant in North America abruptly). Some scientists think it emigrated from Asia, but it’s not likely they crossed bodies of water. May have descended from North American relatives, since there were early Cretaceous titanosaurs in the area
• Alamosaurus may have come from Asia crossing the Bering Strait land bridge (Alamosaurus is part of the Opisthocoelicaudiinae group of titanosaurs, and the type genus of that group is from Asia). But this group is also within Saltasauridae, and Alamosaurus has a lot in common with Saltasaurus (so may have come from South America, though South America was probably separated from North America by an ocean in the Cretaceous; also, other South American dinosaurs like abelisaur theropods, not found in North America, and North American tyrannosaurs not found in South America
• Could be convergent evolution instead
• One study found that as many as 350,000 Alamosaurus may have lived in Texas (area) at any given time
• Quadrupedal, with a long neck and tail and long limbs
• Had some bony armor
• In 2015, Michael Brett-Surman confirmed (nased on findings in 2009) that blocks of bone impressions containe osteoderms
• Osteoderms: bony plates on the skin (found in other titanosaurs)
• No skull found, but rod-shaped teeth have been found nearby Alamosaurus skeletons (so probably Alamosaurus teeth)
• Dinosaurs that lived alongside Alamosaurus included tyrannosaurs, smaller theropods, hadrosaurs, ankylosaurs, and ceratopsids
• Juvenile Alamosaurus may have been prey to tyrannosaurs like Daspletosaurus and Bistahieversor (though adult would have been too large)
• Alamosaurus appears in PBS Kids’ Remember the Alamosaurus
• Gilmore only classified it as a general sauropod (wasn’t sure in 1922 about other classifications); Friedrich von Huene classified it as a Titanosaur in 1927
• Still, unclear where exactly it falls in the Titanosaur group
• Titanosaurs were a group of sauropods, and some of the heaviest land animals
• Argentinosaurus is estimated to have weighed up to 90 tons
• They are named for the now dubious genus Titanosaurus (after the Titans of ancient Greece)
• Not all paleontologists consider it a group, because Titanosaur is dubious
• Last group of sauropods
• Widespread, lived in Antarctica and Australia and NewZealand
• Titanosaurs had small heads, even for sauropods (also wide heads)
• Fragmentary fossils, and not many skulls found
• Large nostrils, and crests formed by nasal bones
• Had small teeth (spoon like or pegs or pencil like)
• Whip like tails (but not as long as diplodocids)
• Had wider chests than most sauropods and a wide stance
• Stocky forelimbs longer than hind limbs
• Skin impressions show they may have had bead like scales, or even bony plates like ankylosaurs
• A titanosaur nesting ground was found in Argentina and Spain (several hundred holes with clutches, around 25 eggs in each clutch)
• Fun fact: In Jurassic World, there is a line at the end of the movie where the boy Gray is adding up teeth of the fighting dinosaurs and says “we need more teeth.” If that were the case, he should have gotten a hadrosaur involved, because they could have almost 1,000 teeth, compared to T-rex which only had about 60.