(11-09-2019, 06:35 AM)DinoFan83 Wrote: So what I've noticed is that gigantism in sauropods, contrary to what most books and articles will tell you, seems to be rather widespread and maybe even patchy.
Overall, there don't seem to be many very large sauropods up until ~160 million years ago, when 75 tonne Mamenchisaurus sinocanadorum and ~50 tonne Xinjiangtitan appear on the scene. The next giant sauropods are all concentrated in North America, Europe, and Africa (they were joined at the time) from 150 to 145 million years ago. There was Supersaurus (35-40 tonnes, found in North America and Europe), Camarasaurus (47 tonnes, North America), Turiasaurus (50 tonnes, Europe), Brachiosaurus (at least 50 tonnes, found in North America, Europe, and Africa), Apatosaurus (up to 95 tonnes, North America), and Barosaurus (up to 100 tonnes, found in North America and Africa). After that, there aren't many known giant sauropods up until ~125 million years ago, with the 2 most prominent examples (Ruyangosaurus and Sauroposeidon, at 100 and 60 tonnes respectively) from China and North America. Around 100 million years ago, South America explodes as a giant dinosaur haven and stays that way till the end of the Mesozoic. You have Patagotitan (69 tonnes, subadult), Andesaurus (40-70 tonnes), Argentinosaurus (73 plus tonnes), Futalognkosaurus (50 tonnes), Notocolossus (76 tonnes), Dreadnoughtus (44 tonnes and a juvenile), and Puertasaurus (100 tonnes), in that order chronologically from around 100 million years ago to the end of the Mesozoic. Meanwhile, in Europe, there's the French Monster from 110-100 million years ago, an unnamed titanosaur known from a 2.75 meter femur, and in Africa, Paralititan at 70 tonnes. And at the end of the Mesozoic in North America, there's Alamosaurus, which is theorized to have reached Argentinosaurus territory mass wise.
So it looks like sauropod gigantism seems to be a bit more random than is commonly thought.