Episode 51 is all about Alamosaurus, the one recognized sauropod to dwell within the Cretaceous in what’s now North America.
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On this episode, we talk about:
- The dinosaur of the day: Alamosaurus
- Title means “Ojo Alamo lizard”
- Just one species: Alamosaurus sanjuanensis
- Holotype present in June 1921, by Charles Gilmore, John Reeside and Charles Sternberg within the Ojo Alamo Formation of New Mexico (some name it the Kirtland Formation); different bones since present in Utah and Texas (juvenile present 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 but been present in Texas
- Title comes from Ojo Alamo, the geologic formation the place the bones have been discovered (which was named after the Ojo Alamo buying and selling publish); some debate although over whether or not to reclassify the world because the Kirtland Formation or keep the Ojo Alamo Formation
- In Spanish the phrase alamo means “poplar”, which is the native cottonwood tree
- Sanjuanensis is known as after San Juan County, New Mexico the place the bones have been discovered
- Gilmore posthumously described a extra full Alamosaurus in 1946, that was present in 1937 (in Utah, by George Pearce); discovered an entire tail, proper forelimb (no fingers)
- Since then, lots of of items of fossils present in Texas, New Mexico and Utah have been known as Alamosaurus
- Fossils have been discovered of a juvenile and three fragmentary specimens
- Not any actually full specimens have been discovered (tends to be extra widespread to seek out juveniles as a result of sediment covers smaller our bodies extra simply)
- Most full specimen is the juvenile present in Texas
- Bits of Alamosaurus skeletons are among the most typical finds of late Cretaceous fossils within the southwest of the U.S., and are used to assist outline the fauna from then, known as the “Alamosaurus fauna”
- Discovered vertebrae and limb bones, which present it was across the similar dimension as Argentinosaurus and Puertasaurus (often is the largest recognized dinosaur in North America); might have weighed as a lot as 73 tons
- Dana Biasetti, a grad pupil from the College of Texas in Dallas, discovered pelvic bones and ten articulated cervical vertebrae of an grownup Alamosaurus in 1999 within the Javelina Formation of Huge Bend Nationwide Park (“Huge Bend Alamosaurus“); might have been as much as 100 ft lengthy and weighing over 50 tons
- Earlier than, estimate was about 65 ft or 20 m lengthy (primarily based on juvenile skeleton and partial grownup skeletons)
- The bones have been so massive and the world so distant that Huge Bend Nationwide Park issued a allow to take away the bones by way of helicopter, and in 2001 it was the primary “dinosaur airlift”
- Holly Woodward in 2009 discovered that the femur of an Alamosaurus bone was nonetheless rising, so researchers knew it bought larger
- Alamosaurus lived within the Cretaceous in North America
- There’s a 30 million yr hole the place sauropods appear to have died out in North America and when Alamosaurus appeared
- Sauropods appear to have been extra widespread on the finish of the Jurassic (as an alternative of Cretaceous); however may very well be we simply haven’t discovered the fossils of extra sauropods but (some sauropods from the Cretaceous in North America embody Astrodon, Sauroposeidon and Cedarosaurus
- Alamosaurus might show immigration from South America (seems and is dominant in North America abruptly). Some scientists assume it emigrated from Asia, nevertheless it’s not going they crossed our bodies of water. Might have descended from North American relations, since there have been early Cretaceous titanosaurs within the space
- Alamosaurus might have come from Asia crossing the Bering Strait land bridge (Alamosaurus is a part of the Opisthocoelicaudiinae group of titanosaurs, and the sort genus of that group is from Asia). However this group can be inside Saltasauridae, and Alamosaurus has so much in widespread with Saltasaurus (so might have come from South America, although South America was in all probability separated from North America by an ocean within the Cretaceous; additionally, different South American dinosaurs like abelisaur theropods, not present in North America, and North American tyrannosaurs not present in South America
- Might be convergent evolution as an alternative
- One research discovered that as many as 350,000 Alamosaurus might have lived in Texas (space) at any given time
- Quadrupedal, with an extended neck and tail and lengthy 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 pores and skin (present in different titanosaurs)
- No cranium discovered, however rod-shaped enamel have been discovered close by Alamosaurus skeletons (so in all probability Alamosaurus enamel)
- Dinosaurs that lived alongside Alamosaurus included tyrannosaurs, smaller theropods, hadrosaurs, ankylosaurs, and ceratopsids
- Juvenile Alamosaurus might have been prey to tyrannosaurs like Daspletosaurus and Bistahieversor (although grownup would have been too massive)
- Alamosaurus seems in PBS Youngsters’ Keep in mind the Alamosaurus
- Gilmore solely categorized it as a basic sauropod (wasn’t certain in 1922 about different classifications); Friedrich von Huene categorized it as a Titanosaur in 1927
- Nonetheless, unclear the place precisely it falls within the Titanosaur group
- Titanosaurs have been a bunch of sauropods, and among the heaviest land animals
- Argentinosaurus is estimated to have weighed as much as 90 tons
- They’re named for the now doubtful genus Titanosaurus (after the Titans of historic Greece)
- Not all paleontologists take into account it a bunch, as a result of Titanosaur is doubtful
- Final group of sauropods
- Widespread, lived in Antarctica and Australia and NewZealand
- Titanosaurs had small heads, even for sauropods (additionally large heads)
- Fragmentary fossils, and never many skulls discovered
- Massive nostrils, and crests shaped by nasal bones
- Had small enamel (spoon like or pegs or pencil like)
- Whip like tails (however not so long as diplodocids)
- Had wider chests than most sauropods and a large stance
- Stocky forelimbs longer than hind limbs
- Pores and skin impressions present they might have had bead like scales, and even bony plates like ankylosaurs
- A titanosaur nesting floor was present in Argentina and Spain (a number of hundred holes with clutches, round 25 eggs in every clutch)
- Enjoyable truth: In Jurassic World, there’s a line on the finish of the film the place the boy Grey is including up enamel of the combating dinosaurs and says “we want extra enamel.” If that have been the case, he ought to have gotten a hadrosaur concerned, as a result of they may have nearly 1,000 enamel, in comparison with T-rex which solely had about 60.