Euhelopus

*Euhelopus zdanskyi*

***Euhelopus*** is a genus of Euhelopodidae Sauropod dinosaur that lived during the Early Cretaceous, between 130 and 112 million years ago. It lived in what is now Shandong Province in China. A large herbivore, it weighed approximately 15-20 tons and attained an adult length of 15 meters (50 feet). Unlike most other sauropods, Euhelopus had longer fore legs than hind legs.

## Description

### Size

Since its original description, Euhelopus has often been considered a rather large sauropod. It has been thought to weigh about 15–20 tonnes (17–22 tons) and attain an adult length of 15 metres (49 feet). Later estimates have downsized this considerably. In 2016, Gregory S. Paul estimated the weight at 3.5 tonnes (3.9 tons) and the body length at 11 metres (36 feet). Benson et al. estimated its mass as 5,924 kg. Larramendi et al. later estimated its mass as 3,628 kg.

### Overall anatomy

Euhelopus was a relatively long-necked sauropod, with a 4-meter neck composed of 17 cervical vertebrae. The presacral vertebrae had a camellate pneumatic structure, made of many small pneumatic chambers, as is characteristic of titanosauriforms and some mamenchisaurids. Pneumatic chambers even extended into the ilium, as occurs in many titanosaurs. The humerus was apparently nearly as long as the femur, although there is some uncertainty in this ratio, as it is not certain that the humerus and femur from which this ratio was calculated belong to the same individual, and the femur in question is incomplete.

### Distinguishing anatomical features

The original diagnosis by Wiman is outdated. A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some of the features in a diagnosis may be autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to an organism or group.

According to a study by Jeffrey A. Wilson and Paul Upchurch in 2009, Euhelopus can be distinguished based on, among others, these autapomorphies:

* The teeth are inclined to the front as proven by the edge of the enamel at the front of the tooth running more in the direction of the top and a front buttress also located more closely to the top.
* The axis, the second neck vertebra, has a hollow at the rear of its neural spine, with three deeper pneumatic depressions in it.
* The postaxial cervical vertebrae, the neck vertebrae behind the axis, have variably developed epipophyses and more subtle "pre‐epipopophyses" below the prezygapophyses, projections on the front of the ridge between the prezygapophysis and the vertebral body.
* The cervical neural arches have an epipophyseal‐prezygapophyseal lamina, a horizontal ridge running from the epipophysis to the prezygapophysis, separating two pneumatocoels by dividing the usual depression at the side base of the neural spine.
* In the neck vertebrae the pleurocoels are reduced to foramina, smaller openings.
* In the neck vertebrae the neural spines are reduced in height and length.
* The third neck vertebra has a neural spine with a transversely flattened forwardly directed process.
* The anterior cervical vertebrae have three costal spurs between the tuberculum and capitulum, the heads of their ribs.
* The neck rib shafts are strongly positioned below the vertebral body due to an appending parapophysis and a long section between the two rib heads.
* The middle presacral neural spines, of the rear neck and front back, are divided or forked, and in the neck base and anterior dorsal vertebrae bear a median tubercle that is at least as large as the metapophyses, the prongs of the fork, resulting in a "trifid" condition.
* The middle and posterior dorsal parapophyseal and diapophyseal laminae are arranged in a "K" configuration.
* The presacral pneumaticity extends into the ilium, which thus is permeated by air chambers.

## Discovery and naming

It was originally named *Helopus*, meaning "Marsh Foot" by Carl Wiman in 1929, but this name already belonged to a bird. It was renamed *Euhelopus* in 1956 by Romer. There is a plant genus (a grass) with the same generic name. However, a genus in one biological kingdom is allowed to bear a name that is in use as a genus name in another kingdom, and the name *Euhelopus* has been allowed. The type species is *Euhelopus zdanskyi*. *Euhelopus* is known from a partial skeleton composed of most of the neck and spinal column and a skull that was missing its teeth. The type material is in the Paleontological Museum of Uppsala University, Uppsala, Sweden.

## Classification

Wiman in 1929 was uncertain about the affinities of Helopus and placed it in a Helopodidae of its own. Yang made this a Helopodinae, first within the Morosauridae, then within the Brachiosauridae. Romer in 1956 created a Euhelopodinae. In 1990, John Stanton McIntosh placed Euhelopus in the Camarasauridae.

The phylogenetic affinities of Euhelopus are controversial, and it has been variously interpreted as having close affinities to Mamenchisaurus-like taxa or as being grouped together with titanosaurs in the clade Somphospondyli. The clade containing Euhelopus and its close relatives is known as Euhelopodidae, but the ambiguity over Euhelopus's affinities has caused considerable uncertainty regarding the membership of Euhelopodidae. Most studies favor the somphospondyl hypothesis for Euhelopus, but the lack of research on the anatomy of Mamenchisaurus-like sauropods has inhibited a rigorous test of the relationship between them and Euhelopus.

Wilson and Upchurch (2009) noted that cladistic assessments suggest that Euhelopus belonged to a clade of sauropods, the Euhelopodidae, that originated during an interval of geographic isolation and was endemic to this geographical range in China. It is not clear if the Euhelopodidae are monophyletic. Euhelopus demonstrates phylogenetic affinity to the taxon Titanosauria. Traditional claims that Euhelopus, Omeisaurus, Mamenchisaurus and Shunosaurus form the monophyletic family “Euhelopodidae” are not supported by new phylogenetic analysis. The cladogram below follows José L. Carballido, Oliver W. M. Rauhut, Diego Pol and Leonardo Salgado (2011).

## Paleoecology

### Provenance and occurrence

The type material for Euhelopus was excavated at the Mengyin Formation in Shandong (Shantung) Province, China. The specimens were collected by Otto Zdansky in 1923, in green/yellow sandstone and green/yellow siltstone.

The Mengyin Formation dates to the Berriasian-Valanginian. It was previously regarded as having been deposited during the Barremian or Aptian stages of the Cretaceous period, about 129 to 113 million years ago. During the 1990s it was mistakenly thought the formation might date from the Late Jurassic.

## JPInstitute.com Description

This long-necked sauropod plant-eater from China was the first of these types of dinosaurs to be discovered in that country, back in 1929. The entire front portion of the skeleton, including the skull, was found in tact, so scientists know almost exactly what this creature looked like. Its nose was located on top of its head and in front of its eyes, a feature seen in sauropods like Brachiosaurus and Camarasaurus.

Euhelopus had a blunt skull, fairly camarasaurid in shape, and had the spoon-shaped teeth common to that family of dinosaurs. It also had some characteristics, such as its pelvis, similar to Omeisaurus. The earliest life restoration of this dinosaur pictured it as a water dweller, with its nose peeking out above the surface. This was discounted as this view of sauropods was discarded.

## Links

http://web.archive.org/web/20040214171330fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_euhel.html