Neosauropoda
Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as Saltasaurus loricatus, Diplodocus longus, and all animals directly descended from their most recent common ancestor. The group is composed of two subgroups: Diplodocoidea and Macronaria. Arising in the early Jurassic and persisting until the Cretaceous-Paleogene extinction event, Neosauropoda contains the majority of sauropod genera, including genera such as Apatosaurus, Brachiosaurus, and Diplodocus.[1] It also includes giants such as Argentinosaurus, Patagotitan and Sauroposeidon, and its members remain the largest land animals ever to have lived.[2]
When Bonaparte first coined the term Neosauropoda in 1986, he described the clade as comprising “end-Jurassic” sauropods. While Neosauropoda does appear to have originated at the end of the Jurassic period, it also includes members throughout the Cretaceous. Neosauropoda is currently delineated by specific shared, derived characteristics rather than the time period in which its members lived.[3] The group was further refined by Upchurch, Sereno, and Wilson, who have identified thirteen synapomorphies shared among neosauropods.[4] As Neosauropoda is a subgroup of Sauropoda, all members also display basic sauropod traits such as large size, long necks, and columnar legs.[5]
Paleontologist Richard Owen named the first sauropod, Cetiosaurus, in 1841. Due to the fragmentary evidence, he originally believed it to be a type of massive crocodile. Cetiosaurus has at times been classified as a basal member of Neosauropoda, which would make it the first member of this group discovered.[6] Most current research, however, places Cetiosaurus outside Neosauropoda as a sister taxon.[7] The first dinosaurs discovered which are conclusively known to fall within Neosauropoda were Apatosaurus and Camarasaurus, both found in North America in 1877, and Titanosaurus discovered the same year in India.[8] There were other sauropods besides Cetiosaurus which were described before the 1870s, but most were known from only very fragmentary material and none were described in sufficient detail that they may conclusively be classified as neosauropods. A great number of neosauropod skeletons were unearthed in western North America during the late nineteenth and early twentieth centuries, primarily Apatosaurus, Camarasaurus, and Diplodocus.[6]
