Dreadnoughtus schrani: Frequently Asked Questions on the Super-Massive Dinosaur

Dreadnoughtus schrani was substantially more massive than any other supermassive dinosaur for which mass can be accurately calculated. Credit: Lacovara Lab, plus detailed citations
An artist’s rendering of the dinosaur Dreadnoughtus schrani in life. Dreadnoughtus had a 37-foot-long neck, 30-foot tail, and weighed an estimated 65 tons, making it the most massive land animal whose size can be accurately calculated. In life, Dreadnoughtus was an herbivore that likely spent much of its life eating massive quantities of plants to maintain its enormous body size. Credit: Jennifer Hall
An artist’s rendering of the dinosaur Dreadnoughtus schrani in life. Dreadnoughtus had a 37-foot-long neck, 30-foot tail, and weighed an estimated 65 tons, making it the most massive land animal whose size can be accurately calculated. Credit: Jennifer Hall

In a scientific paper published in the journal Scientific Reports today, a Drexel-led team has described a new genus and species of dinosaur they have named Dreadnoughtus schrani. An overview of the discovery and its significance is available in the press release here. Below are answers to some commonly asked questions, placing Dreadnoughtus in the context of other enormous dinosaurs and providing more background information about the discovery.

Q: Is Dreadnoughtus schrani the world’s largest dinosaur?

A: Sauropod dinosaurs (long-necked plant eaters) include the largest land animals that have ever existed. Multiple studies have shown that the body weight of a quadrupedal (four-legged) animal corresponds closely with measurements taken from its humerus (upper arm bone) and femur (thigh bone). Many paleontologists consider this approach to be the only reliable method of calculating the weight of an extinct quadrupedal creature, such as a sauropod. There are a number of extremely large dinosaurs, but many of these are based on very incomplete fossils that lack a humerus and/or a femur. As such, their body weight is impossible to calculate with this method. Thus, Dreadnoughtus has the largest calculable weight of any known land animal.

Q: How big was Dreadnoughtus?

A:

Weight 65 tons (59.3 metric tons)
Total length 85 feet (26 m)
Head & neck length 40 feet (12.2 m)
Neck length 37 feet (11.3 m)
Torso and hip length 17 feet (5.1 m)
Tail length 29 feet (8.7 m)
Height (at shoulder) 2 stories
Dreadnoughtus schrani was substantially more massive than any other supermassive dinosaur for which mass can be accurately calculated. Credit: Lacovara Lab, plus detailed citations
Dreadnoughtus schrani was substantially more massive than any other supermassive dinosaur for which mass can be accurately calculated. Credit: Lacovara Lab, plus detailed citations

Q: How does Dreadnoughtus compare to the giant dinosaur from Patagonia reported in the media in May 2014?

A: The May 2014 report was based on claims that have not been formally vetted by the scientific community. In other words, information on these fossils has not yet been the subject of a peer-reviewed, published study. As such, it is currently impossible to compare them (or the dinosaur species they represent) to other specimens.

Q: Is Dreadnoughtus larger than Argentinosaurus?

A: There is no doubt that Argentinosaurus is an extremely large dinosaur and a contender for the most massive land animal yet discovered. However, Argentinosaurus is based on very fragmentary remains (only 13 bones out of approximately 250 in a whole skeleton), from which a reliable mass estimation is impossible.

Q: When was Dreadnoughtus discovered?

A: February of 2005

Q: Who discovered Dreadnoughtus?

A: Kenneth Lacovara, PhD, discovered the dinosaur while prospecting for fossils in Santa Cruz Province, Argentina. Lacovara spotted a small patch of bones and recorded the location with his GPS. The team returned a few hours later and began excavating. By the end of the day, they had exposed about ten bones of what would come to be known as Dreadnoughtus schrani.

Q: How many bones of Dreadnoughtus were found?

A: After four expeditions, the team had excavated a total of 145 bones and a single tooth representing two individuals of Dreadnoughtus schrani – 115 bones (and the tooth) from the larger specimen and 30 bones from a second, smaller individual.

The skeleton of Dreadnoughtus schrani in place during excavation in Argentina. Credit: Kenneth Lacovara
The skeleton of Dreadnoughtus schrani in place during excavation in Argentina. Credit: Kenneth Lacovara

Q: How complete is the skeleton of Dreadnoughtus?

A: Completeness may be assessed in different ways. Sauropod dinosaur skeletons are often recovered with little to no skull material, so completeness is often looked at in terms of postcranial completeness (i.e., the completeness of the skeleton excluding the skull). Completeness may also be assessed in terms of numbers of bones versus types of bones. The most important metric for understanding the anatomy of a fossil animal is types of bones. The completeness ‘statistics’ for Dreadnoughtus schrani are as follows:

  • 116 bones out of ~256 in the entire skeleton (including the skull) = 45.3 percent complete
  • 115 bones out of ~196 in the skeleton (excluding the skull) = 59 percent complete
  • 100 types of bones out of ~142 types in the skeleton (excluding the skull) = 70.4 percent complete

Q: How does Dreadnoughtus compare in terms of completeness with other super-massive dinosaurs?

A: Prior to the publication of Dreadnoughtus schrani, the most completely known super-massive titanosaur was Futalognkosaurus dukei, which is represented by

15.2 percent of the total skeleton and 26.8 percent of the types of bones in the skeleton (excluding the skull). Argentinosaurus is known from only 5.1 percent of the entire skeleton and 9.2 percent of the types of bones in the postcranial skeleton. Thus, the skeleton of Dreadnoughtus schrani is more complete than those of all other super-massive dinosaurs.

Of the 142 types of bones not including the skull, 100 types of bones, or 70.4 percent, are represented in the Dreadnoughtus skeleton. Skull bones from any titanosaur are extremely rarely recovered. Credit: Lacovara Lab, Drexel University
Of the 142 types of bones not including the skull, 100 types of bones, or 70.4 percent, are represented in the Dreadnoughtus skeleton. Skull bones from any titanosaur are extremely rarely recovered. Credit: Lacovara Lab, Drexel University

Q: How old were the Dreadnoughtus individuals at the time of their death?

A: The exact ages of these two individuals are not clear. However, multiple lines of evidence indicate that the larger Dreadnoughtus was growing rapidly at the time of its death. The shoulder bones of this individual are not fused together, as would be expected in a mature adult. Furthermore, microscopic analysis of the bones of this specimen revealed none of the cellular structures expected in a mature individual. Shockingly, at the time of its death, the 65-ton Dreadnoughtus was still growing fast.

Q: How did the Dreadnoughtus individuals die?

A: There is no evidence of traumatic injury for either individual. There are a few tooth marks on a single vertebra that likely represent scavenging by a much smaller meat-eating dinosaur. It appears that both individuals died and were buried rapidly after a river flooded and broke through its natural levee, turning the ground into a soupy mixture of sand, mud and water. The rapid and deep burial of the larger Dreadnoughtus schrani specimen accounts for its extraordinary completeness.

Q: How was Dreadnoughtus transported to the United States?

This slideshow requires JavaScript.

A: In the field, the bones of Dreadnoughtus were ‘jacketed’ in burlap and plaster to protect them during transportation. Because some bones were fragmented into more than one piece, a total of 234 plaster jackets, weighing 16 tons, were created. The jackets were loaded into a cargo container and shipped by sea to Philadelphia on the Hamburg Süd freighter Cap San Lorenzo. The voyage took approximately six weeks and Dreadnoughtus visited a dozen ports along the coast of South America on its journey. The fossils arrived in Philadelphia on May 9, 2009.

Q: What happened to the fossils after their arrival?

A: Fossils shipped in plaster jackets require a lot of work, or preparation, before they can be safely studied. Dreadnoughtus was shipped in more jackets than any one lab could handle, so the material was divided into thirds and shipped to Carnegie Museum of Natural History in Pittsburgh, The Academy of Natural Sciences of Drexel University and Lacovara’s lab at Drexel. In 2012, all of the fully cleaned and restored material was reunited in Lacovara’s lab for study.

Q: How were the bones of Dreadnoughtus turned into 3D images?

A: All of the bones of both Dreadnoughtus specimens were scanned in Dr. Lacovara’s lab with a NextEngine 3D laser scanner. Using the software Autodesk Maya, the scans of each bone were positioned in 3D space to create a digital articulated skeleton, which was then converted into 3D PDF files using the software GeoMagic.

Q: Can anyone access the 3D images of Dreadnoughtus schrani?

A: Yes. Lacovara et al. published 3D PDF files of the entire skeleton and selected bones in the supplementary section of their paper. The files may be used by anyone with access to Adobe Reader software, which is freely available for download here: http://get.adobe.com/reader/. In Adobe Reader, the viewer can zoom in and out on the skeleton, rotate the view, and turn individual bones on and off. The 3D PDF files of Dreadnoughtus may be downloaded here: http://dx.doi.org/10.6084/m9.figshare.1130885.

Members of the Lacovara lab (in Dec. 2012) from left to right, Anna Jaworski, Paul Ullmann, Kenneth Lacovara, Elena Schroeter, Kristyn Voegele, Zachary Boles
Members of the Lacovara lab at Drexel University (in Dec. 2012) from left to right, Anna Jaworski, Paul Ullmann, Kenneth Lacovara, Elena Schroeter, Kristyn Voegele, Zachary Boles

Q: Is there additional research underway on Dreadnoughtus?

A: Yes. Lacovara’s research group and colleagues have numerous studies in progress. The Sept. 4, 2014 paper describing Dreadnoughtus schrani established the new genus and species and described the unique features of its anatomy. Subsequent papers will focus on topics including the musculature, biomechanics, growth rate, and the biomolecular preservation of the Dreadnoughtus specimens.

Q: Who owns Dreadnoughtus?

A: The Province of Santa Cruz, Argentina. The specimen is in the United States on a research loan from the provincial government.

Q: When will Dreadnoughtus schrani return to Argentina?

A: The fossils will be returned to Argentina in 2015, after which they will reside permanently in the Museo Padre Molina in Río Gallegos, Argentina.

Q: Can anyone access the paper by Lacovara et al. describing Dreadnoughtus schrani?

A: Yes. The paper is published in the open access, online journal Scientific Reports (published by Nature Publishing Group) and may be freely viewed and downloaded here: http://dx.doi.org/10.1038/srep06196.

Note to news media: Additional resources, including available multimedia resources and other information about Dreadnoughtus schrani are available from the Dreadnoughtus resource page at https://newsblog.drexel.edu/dinosaur.

For news media interview requests for Kenneth Lacovara, contact Rachel Ewing, raewing@drexel.edu, 215.895.2614.