Deviation Actions
Description
Sauropod dinosaurs thrived throughout the Mesozoic. From the humble beginnings of the sauropodomorphs of the Triassic and Early Jurassic, to reaching their apex throughout the Jurassic to include the whip-tailed Diplodocids, Asian Mamenchisaurs, and short-snouted tree browsing Macronarians, and by the end of the Cretaceous, the derived Titanosaurs. The lattermost had become some of the largest terrestrial animals that ever lived. The last and one of the largest of these titans came from the American Southwest, Alamosaurus sanjuanensis.
History:
In 1921, a paleontologist from the Smithsonian Charles W. Gilmore and famed fossil hunter Charles H. Sternberg were prospecting for fossils in the American Southwest. At the time, the fossils in the region were rather spars, however, in June they found something interesting. A fossilized Ischium (part of the pelvis) and scapula (shoulder). In 1922, Gilmore described the holotype fossils in a paper published by the Smithsonian.
Naming:
Contrary to popular belief, it was not named after the Battle of the Alamo in San Antonio, Texas. As previously mentioned, the first fossils were found in a region called the Ojo Alamo Formation which is where the bulk of the fossils were found. Thus, the genus name was named after the formation. The species named after the county, San Juan County of New Mexico. Thus, the entire binomial name derived from Greek is “San Juan’s Alamo Lizard”, Alamosaurus sanjuanensis.
Description and Size:
Alamosaurus has the standard Titanosaurian body plan. A long, but sturdy tail, massive torso, robust and sturdy limbs, and a long neck held vertically off the ground. The skull of this animal is not known, however, it’s believed that it fed upon conifer trees and had teeth designed to strip branches of foliage.
Some paleo artists depict this dinosaur with osteoderms on the flanks and tail. Primarily based on some titanosaur fossils found from Europe, however, there is no evidence that this was present in American Titanosaurs, so as of now, it’s speculative.
The size of this dinosaur was, until recently, believed to be average or below average for a large sauropod. Around 40-55ft long which is size based on the holotype USNM 10486, another find, USNM 15660 seemed to confirm this scale. However, a study published in 2013 describes fossil material labeled BIBE 45854 which is now held at the Ross Perot Museum. Discovered from rocks in Texas, it consists of cervical vertebrae that is truly gargantuan compared to other Cretaceous aged American Sauropods. From extrapolating data from these bones, it has been theorized that owner of these vertebrae would have been around 85-100ft long. The remains have been attributed to Alamosaurus, and reanalysis of the bones indicate that the smaller specimens aren’t fully grown and consist of subadults or juveniles. Thus, the last sauropod that inhabited North America may have been one of the largest.
Weight is something that cannot be extrapolated beyond a few estimates. However, the current estimates are between 45-85 tons. The middle ground between 45-60 tons is now generally accepted. Still, a massive dinosaur, on par with some Jurassic titans and the South American Lognkosaurs.
Taxonomic placement and Evolution:
Early on, many paleontologists think this dinosaur evolved from Asian sauropod species Opisthocoelicaudia and was a member of the Opisthocoelicaudiinae subfamily. A 2002 study pointed out derived characteristics of the forelimb which are comparable to Opisthocoelicaudia. This is where many sauropod experts fell until recently. However, there were questions that arose from this theory. The largest one is that no fossils have been found of transitional forms of Sauropods in any region. Taphonomy could have been a reason why, but, to find no Sauropod fossils in Late Cretaceous North America until this Titanosaur arose was puzzling.
A more recently accepted viewpoint is that these dinosaurs arose from a taxon outside of the larger Lognkosauria group of Titanosaurs with animals like Argentinosaurus, Patagotitan, and Mendozasaurus. Being a close relative of Lithostrotia, with animals like Saltosaurus, this would make these dinosaurs arising out of South American sauropods. Which makes sense, it’s closer, has a far more prevalent sauropod fossil record, and their morphology resembles them.
Habitat:
Alamosaurus was generally confined to the American Southwest. Fossils from Utah, New Mexico, and Texas have been described. The environment would have been a scrubby, coastal environment. Throughout its evolution, it lived relatively close to the coast of the Western Interior Seaway, and what remained of it after it retreated at the end of the Cretaceous. River systems flowing inland would have provided lush habitat for the ecosystem with scattered woodlands and floodplains also being common.
Alamosaurus thrived in the Southwest for 4,000,000 years right up until the end of the age of Dinosaurs some 66,000,000 years ago. Contemporary fauna included some recognizable animals like the ceratopsian Torosaurus, and the hadrosaur Kritosaurus existed alongside it. More obscure ceratopsian dinosaurs like Bravoceratops and Ojoceratops as well as the dromaeosaur Dineobellator were also found among the formations this dinosaur resided in.
Arguably the most famous co-inhabitant would be the legendary King of Dinosaurs Tyrannosaurus rex. There are common depictions in paleoart showing T.rex or a pack of T.rex hunting an Alamosaurus which is an irresistible image to picture, the Tyrant Lizard King preying upon a sauropod. However, there is no direct evidence that T.rex actually hunted these sauropods. If T.rex hunted these animals, it likely would have only targeted juvenile dinosaurs.
Extinction:
Being the last of the Sauropods, existing right up until the end of the dinosaurs’ reign, it’s no mystery how this animal went extinct. 66,000,000 years ago, an asteroid struck the earth and marked the end of the Non-Avian Dinosaurs.
Alamosaurus was likely the first victim of the KT Extinction Event being so close to the impact. This titanic sauropod species was wiped off the face of the earth by forces that came from beyond their world. Likely experiencing the blistering heat from the impact and blown away from the impact’s forces as if it were a speck of dust on the floor.
Now, all that remains are the fragmentary fossils of this Sauropod. Reminders of a titan that existed in a bygone era long forgotten.
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Currently I’ve got some vacation time which I’m using right now, so thought I’d knock out some more dinosaur profiles that I started last year when I first started working on PMP.
Will this be in PMP itself? Originally, I did plan to go to the Ojo Alamo Formation for the final episode, but, ultimately, I went with Hell Creek. Mainly because there were more interesting scenes I could craft.
I KNOW 3/6 of the episodes of S1 (Pleistocene Eurasia, Morrison Formation, and Hell Creek) have been kind of done to death, but I really have no other options with some acquaintances of mine and myself working on more animals.
The other Ceratopsian in the pic, Ojoceratops, I’ll feature in a profile, soon. Just had some more negative space and wanted to use it here. I didn’t want to use a Tyrannosaurus, because the T.rex vs. Alamosaurus has been done to death. So, I just put a small group of them in this pic.
So the Ojoceratops is made by me, The Alamosaurus’ skin is from ZT2 Thailand, BUT I modified the model and skin so things look more seamless in terms of skin and model quality.
Ojoceratops made by me modified from Tyranachu’s Triceratops:
Triceratops (Tyranachu) | ZT2 Download Library Wiki | Fandom
Alamosaurus by ZT2 Thailand, modified by me:
Alamosaurus (Zoo Tycoon 2 Thailand) | ZT2 Download Library Wiki | Fandom
And your question about whether Alamo being a lognkosaur now makes sense...
One point which you touched on in the text is the osteoderms which you have placed on the back (in common with many other artists). But what is the purpose? If it's to deter predators, then it would Tyrannosaurus to carry a ladder in order to reach that high. I don't see how it could be used in intraspecies combat either. Just think raised osteoderms along the back would be an unlikely feature in giant sauropods.