Elasmosaurus

Elasmosaurus platyuruselasmosaursElasmosaurus orientalisElasmosaurus intermediusKal-Ta-GootplesiosaursSeasaurus
Elasmosaurus is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5million years ago.wikipedia
276 Related Articles

Plesiosauria

plesiosaurplesiosaursPlesiosaur stratigraphic distribution
Elasmosaurus is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5million years ago.
After having published a description of this animal, followed by an illustration in a textbook about reptiles and amphibians, Cope invited Marsh and Joseph Leidy to admire his new Elasmosaurus platyurus.

Edward Drinker Cope

CopeCope EDCope, E.D.
The first specimen was discovered in 1867 near Fort Wallace, Kansas, and was sent to the American paleontologist Edward Drinker Cope, who named it E.platyurus in 1868.
The fossils he found in these pits became the focus of several papers, including a description in 1868 of Elasmosaurus platyurus and Laelaps.

Bone Wars

rivalBone Warbitter rivalry
Cope originally reconstructed the skeleton of Elasmosaurus with the skull at the end of the tail, an error which was made light of by the paleontologist Othniel Charles Marsh, and became part of their "Bone Wars" rivalry.
Marsh humiliated Cope by pointing out that his reconstruction of the plesiosaur Elasmosaurus was flawed, with the head placed where the tail should have been (or so he claimed, 20 years later; it was Leidy who published the correction shortly afterwards).

Othniel Charles Marsh

MarshO. C. MarshO.C. Marsh
Cope originally reconstructed the skeleton of Elasmosaurus with the skull at the end of the tail, an error which was made light of by the paleontologist Othniel Charles Marsh, and became part of their "Bone Wars" rivalry.
The two began to develop a rivalry when Marsh allegedly pointed out that Cope had placed the skull of Elasmosaurus at the end of its tail.

Campanian

Late CampanianEarly CampanianCampanian age
Elasmosaurus is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5million years ago.

Discosaurus

Discosaurus vetustus
Leidy also concluded that Elasmosaurus was identical to Discosaurus, a plesiosaur he had himself named in 1851.
It was argued to be the same animal as Elasmosaurus.

Crystal Palace Dinosaurs

Crystal PalaceCrystal Palace dinosaur sculptures33 lifesized models
At the time, Hawkins was working on a "Paleozoic Museum" in New York's Central Park, where a reconstruction of Elasmosaurus was to appear, an American equivalent to his life-sized Crystal Palace Dinosaurs in London.
In May 1871 many of the exhibits in Hawkins' workshop were destroyed by vandals and their fragments buried, possibly including elements of the original Elasmosaurus skeleton, which the American palaeontologist Edward Drinker Cope had loaned to Hawkins for preparation at the time.

Elasmosauridae

elasmosauridelasmosaurelasmosaurids
The family Elasmosauridae was based on the genus Elasmosaurus, the first recognized member of this group of long-necked plesiosaurs.
The family Elasmosauridae was erected by Cope in 1869, and anchored on the genus Elasmosaurus.

Brancasaurus

GronausaurusBrancasaurus brancaiGronausaurus wegneri
In 1962 Welles further subdivided elasmosaurids based on whether they possessed pelvic bars formed from the fusion of the ischia, with Elasmosaurus and Brancasaurus being united in the subfamily Elasmosaurinae by their sharing of completely closed pelvic bars.
With a long neck possessing vertebrae bearing distinctively-shaped "shark fin"-shaped neural spines, and a relatively small and pointed head, Brancasaurus is superficially similar to Elasmosaurus, albeit smaller in size at 3.26 m in length.

Dinosaur

dinosaursDinosaurianon-avian dinosaurs
In spite of their many neck vertebrae, the necks of elasmosaurids were less than half as long as those of the longest-necked sauropod dinosaurs.
The feud probably originated when Marsh publicly pointed out that Cope's reconstruction of an Elasmosaurus skeleton was flawed: Cope had inadvertently placed the plesiosaur's head at what should have been the animal's tail end.

Joseph Leidy

LeidyJ. Leidy
At an ANSP meeting a year and a half later, in March 1870, the American paleontologist Joseph Leidy (Cope's mentor) noted that Cope's reconstruction of Elasmosaurus showed the skull at the wrong end of the vertebral column, at the end of the tail instead of the neck.
Marsh claimed Leidy contributed to the falling out of the two by showing Cope in the presence of Marsh that Cope had mistakenly placed the head of a fossil Elasmosaurus on the tail, rather than on the neck, and then publishing a correction.

Polycotylus

Polycotylus latipinnisPolycotylus sopozkoi
Williston also reassigned the species E.ischiadicus from the genus Polycotylus, where he had initially placed it when he named it in 1903.
Unlike some better-known long-necked plesiosaurs like Plesiosaurus and Elasmosaurus, Polycotylus had a short neck.

Styxosaurus

Styxosaurus snowiiHydralmosaurusElasmosaurus nobilis
Subsequently, all Hydralmosaurus specimens were moved to Styxosaurus in 2016, rendering the former a nomen dubium.
Styxosaurus snowii is from a group called elasmosaurs, and is closely related to Elasmosaurus platyurus, which was found in Kansas, USA, in 1867.

Thalassomedon

AlzadasaurusThalassomedon hanningtoniThalassomedon haningtoni
Kenneth Carpenter reassigned it to Thalassomedon haningtoni in 1999; Sachs, Johan Lindgren, and Benjamin Kear noted that the remains represented a juvenile and were significantly distorted, and preferred to retain it as a nomen dubium in 2016.
Its closest relative is Elasmosaurus, and both belong to the family Elasmosauridae.

Paleozoic Museum

At the time, Hawkins was working on a "Paleozoic Museum" in New York's Central Park, where a reconstruction of Elasmosaurus was to appear, an American equivalent to his life-sized Crystal Palace Dinosaurs in London.
Extant drawings by Hawkins, along with other records, indicate that the Paleozoic Museum would have included life-sized restorations of the theropod Laelaps (=Dryptosaurus), the hadrosaurid Hadrosaurus, the plesiosaur Elasmosaurus, and the mosasaur Mosasaurus (all from the Upper Cretaceous marls of New Jersey), along with glyptodont models, a pair of giant ground sloth, giant Pleistocene elk, mammoths, and extinct mammalian carnivores.

Turonian

Early TuronianLate TuronianTuronian age
platyurus and E.orientalis, Cope assigned an additional species, E.constrictus'', based on a partial centrum from a neck vertebra found in the Turonian-aged clay deposits at Steyning, Sussex, in the United Kingdom.

Aristonectes

Aristonectes parvidensAristonectes quiriquinensis
Edwin Colbert later assigned the type vertebra in 1949 to a pliosauroid, and also assigned other referred remains to indeterminate elasmosauroids; the type vertebra was recognized as potentially belonging to Aristonectes parvidens by José O'Gorman and colleagues in 2013.
Aristonectes was classified variously since its original 1941 description, but a 2003 review of plesiosaurs from Patagonia conducted by Gasparini et al. (2003) found that Aristonectes was most closely related to elasmosaurid plesiosaurs like Elasmosaurus.

Terminonatator

Terminonatator ponteixensis
In 2005 Sachs suggested that Elasmosaurus was closely related to Styxosaurus, and in 2008 Druckenmiller and Russell placed it as part of a polytomy with two groups, one containing Libonectes and Terminonatator, the other containing Callawayasaurus and Hydrotherosaurus.
It would have been small as an adult for an elasmosaurid, at only about 7 m long, up to 9 m if it had an extremely long neck like Elasmosaurus (which had 72 neck vertebrae).

Microcleididae

microcleidid
Their analysis also moved Muraenosaurus to the Cryptoclididae, and Microcleidus and Occitanosaurus to the Plesiosauridae; Benson and Druckenmiller isolated the latter two in the group Microcleididae in 2014, and considered Occitanosaurus a species of Microcleidus.
Microcleididae was defined as "Microcleidus homalospondylus and all taxa more closely related to it than to Plesiosaurus dolichodeirus, Cryptoclidus eurymerus, Elasmosaurus platyurus, Leptocleidus superstes, Pliosaurus brachydeirus or Polycotylus latipinnis."

Sauropterygia

eosauropterygiasauropterygianEusauropterygia
Though Cope had originally recognized Elasmosaurus as a plesiosaur, in an 1869 paper he placed it, with Cimoliasaurus and Crymocetus, in a new order of sauropterygian reptiles.
The long-necked plesiosaurs, meanwhile, included both those with medium-long necks, such as the 3 to 5 metre-long Plesiosauridae and Cryptoclididae, and the Jurassic and Cretaceous Elasmosauridae, which evolved progressively longer and more flexible necks, so that by the middle and late Cretaceous the entire animal was over 13 metres in length (e.g. Elasmosaurus) - although, as most of this was the neck, the actual body size was much smaller than that of the larger pliosaurs.

Timeline of plesiosaur research

* With guidance from Edward Drinker Cope, paleo-artist Charles R. Knight illustrated an Elasmosaurus platyurus eating a fish.

Libonectes

Libonectes morganiLibonectes atlasense
In 1997 Carpenter reconsidered the differences between the two species, and found them sufficient to place E.morgani in its own genus, which he named Libonectes.

Plesiosauroidea

plesiosauroidplesiosauroids
He divided plesiosaurs into two superfamilies, the Plesiosauroidea and Pliosauroidea, based on neck length, head size, ischium length, and the slenderness of the humerus and femur (the propodialia).

Fort Wallace

WallaceForts WallacePonds Creek Station
The first specimen was discovered in 1867 near Fort Wallace, Kansas, and was sent to the American paleontologist Edward Drinker Cope, who named it E.platyurus in 1868.