STL Science Center

STL Science Center

13 December 2017

Descriptions of Small Dinosaurs

Hesperonychus has not made much of a buzz since it was initially described. That paper, shared on Saturday initially but here again today (Longrich and Currie, 2009), includes the expected high detail photographs of the type material, but it also includes museum material hypothesized, but not necessarily known, to belong to Hesperonychus. The conclusions that caused this material, isolated pedal phalanges, to be referred to this species, was tentative at the time and has been based on characteristics of size and shape that place the toes in the same family and, because of the size, attribute them to an adult animal approximately the size of the estimated adult size of Hesperonychus. These phalanges are described and compared to the phalanges of other taxa in order to justify their reference to this species of dromaeosaur. Key elements of the pelvic girdle that mark the animal as an adult stand as diagnostic characters that separate Hesperonychus from other genera and the possibility of the small dromaeosaur belonging to another genera as a subadult or even as a juvenile. The characteristic growth described here is fusion of the pubes and ilia, a morphology seen in "somatically mature" animals, as Longrich and Currie state. A phylogenetic discussion is presented as well in an attempt to ascertain the precise clade to which Hesperonychus belongs and its position in both this specific and the larger dromaesaurine clade as well.

11 December 2017

Hesperonychus On-Screen

Hesperonychus has made one appearance on a main screen since its description. A clip of the Walking with Dinosaurs movie, shown here, displays their introduction early in the film. If you want to see more of this small carnivore in the movie, I would recommend watching it. The film was produced by the BBC, in part, and some of the same people behind the BBC's television program of the same name. Additionally, this movie is one of the very few dinosaur movies that aims at more realistic animals, including feathering on their animals, among other things.

10 December 2017

Facts About the Western Claw

Hesperonychus facts pages are somewhat rare on the internet. Rather than going through the few that show up individually, here are a couple that are worth reading today:
DinosaurFacts
BBC

There are no fact videos hosted anywhere online. There is a tribute video on YouTube that can be viewed. A lot of the images used in this video, though, are either generic or are not the dinosaur Hesperonychus; the latter are not identifiable enough to recognize at least. The images loop throughout the video. Enjoy!

09 December 2017

The Western Claw

Discovered in Alberta's Dinosaur Park Formation's Cretaceous strata representing the Campanian stage of 76.5 MYA, Hesperonychus elizabethae is a small dromaeosaur known from a pelvic girdle discovered by Dr. Elizabeth Nicholls of the Royal Tyrrell Museum in 1982. The skeletal element remained in storage until 2009 when it was described by Longrich and Currie (A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America). A number of claws that appear to be allometrically and anatomically related to Hesperonychus, but these have not been described or officially attributed to the small dinosaur. Measuring in at an estimated length of 1 m (3.3 ft) and weight of 1.9 kg (2.2 lbs), Hesperonychus appears to have been a fully adult but one of the smallest carnivores of North America. Despite the small amount of material, the description relied on comparison between this pelvis and the pelves of other dromaeosaurs.
©Nobu Tamura CC BY 3.0

08 December 2017

Drawings of Suzhousaurus

©Masato Hattori
Suzhousaurus is a fairly typical looking therizinosaurid theropod dinosaur. Because Suzhousaurus looks like any other therizinosaur in almost every interpretation that exists, this rather large theropod, estimated to measure approximately 6 m (19.6 ft) and weigh up to 1.3 tonnes, is not the most exciting dinosaur illustration subject. However, the least static of these paleoillustrations is Masato Hattori's low placed, high angled interpretation of Suzhousaurus standing behind short grassy vegetation. This interpretation has a shorter coating of feathers than what is generally depicted on therizinosaurs, but the feathering appears soft and downy; Suzhousaurus may not have been as fuzzy and warm as it appears here, but I do not think that should bother us. It is feasible that Suzhousaurus was more likely to be found in woodlands or at the edges of forests than in a plainscape, as this appears to be, but this view may not mean anything in terms of where the Suzhousaurus is supposed to have been living at the point in time that this illustration may be depicting.

06 December 2017

Papers and Anatomy

In 2007 Suzhousaurus was officially described and announced to the world as a "Large Therizinosauroid" of Northwestern China. The description available online through Acta Geologica Sinica (the English edition for those that cannot read Chinese characters). The description includes detailed color photographs of the skeletal remains as well as maps of the region from where it had been recovered. Therizinosaur specimens and their stratigraphic ages are also cataloged in the description paper. The phylogeny of the therizinosaurs is discussed briefly, but only enough to describe where the new dinosaur Suzhousaurus fit into the family tree. The description of a newer specimen in 2008 by Li, et al. contains more descriptive information about individual skeletal elements of this new Suzhousaurus megatherioides specimen that was discovered in the same general locality as the type specimen (Gansu Province). The diagnosis of some of the material is revisited and redescribed as well as the new material. However, the heart of this description is in the new material and stretches in great detail for a number of pages. Comparisons to other therizinosaurs round out the discussion, but the overall phylogeny of therizinosaurs is not broached in this paper.

03 December 2017

A Presentation for All

This video has an oddly hushed voice reading the facts and offering interpretation, but the strange huskiness of the presenter is a little odd in spots. Despite that, of course, there are a lot of important facts about the therizinosaur Suzhousaurus that are contained within the video. Clearly it was a wide-cast net for a project, but it is a lot of information that is very important for better understanding of the dinosaur. Fact pages on the internet are found sparingly, but there is a Live Science popular science article from around the initial time of publication that helped to announce and disseminate some of the facts about Suzhousaurus.