Tag: theropod

Halszkaraptor

Halszkaraptor escuilliei, a dromaeosaurid (“raptor”) dinosaur from the Late Cretaceous of Mongolia (~75-71 mya). It’s known from a single near-complete skeleton and would have been about the size of a modern mallard duck, around 60cm long (2′).

It had some very odd features for a raptor, with many small sharp backwards-pointing teeth, crocodile-like sensory pits on its snout, a long flexible neck, small flipper-like arms, a relatively short tail, and a more upright body posture than its other relatives. All these traits together suggest it may have been semi-aquatic, which is a pretty big deal since the only other group of non-avian dinosaurs known to have developed adaptations for life in the water were the spinosaurids.

The fossil was originally illegally excavated by fossil poachers and was owned by private collectors for several years, but it has now been returned to science and is due to be repatriated to Mongolia. With its odd anatomy and the exact origin of the specimen being unknown, there’s some skepticism about whether Halszkaraptor represents a genuine animal or an elaborate fake chimera – but synchrotron scans of the fossil and its similarity to previously-discovered more fragmentary short-armed raptors like Mahakala suggest that it is real, and it really is that weird.

Mirischia

Mirischia asymmetrica, a theropod dinosaur from the Early Cretaceous of Brazil (~112-99 mya). Although known only from its hips and a few other partial bones, these pieces were so well-preserved that it was given a genus name that translates to “wonderful pelvis”.

In life it would have been about 2m long (6′6″), but since the known fossil represents a subadult its full-grown size may have been a little bit larger. It was probably a member of the compsognathids, closely related to Compsognathus and Aristosuchus – which would make it the only representative of that family currently known from the Americas.

The ischium bones of Mirischia’s pelvis were oddly asymmetrical, hence the species name ‘asymmetrica’, with one side featuring a hole and the other side only having a notch in the same position. The fossil specimen also had thin-walled bird-like bones, and soft-tissue impressions of intestines and a posterior air sac.

Utahraptor

Utahraptor ostrommaysorum lived during the Early Cretaceous (~130-124 mya) in Utah, USA, and was the largest known dromaeosaurid. Reaching lengths of around 6m long (20′), it’s often compared in size to the fictional raptors of Jurassic Park.

Recent discoveries show it had some weird proportions compared to its relatives – a thick stocky body, chunky legs, smaller arms, a shorter and more flexible tail, and a large deep skull with an oddly curved lower jaw.

But we still don’t know very much about it… yet.

There’s a huge slab of rock full of Utahraptor fossils just waiting to be extracted and studied. There are at least six raptors in there ranging from babies to adults, hinting at the presence of a family group or even pack hunting behavior, and potentially other animals and new discoveries too – but the main roadblock for this project is lack of funding.

The paleontologists involved have turned to crowdfunding to attempt to raise enough money for essential equipment and the services of a professional fossil preparator, but they’re still only at about 10% of their goal.

So this first week of April is #UtahraptorWeek in the paleontology community, raising awareness of this fascinating giant raptor and how close we are to finding out so much more about it. Spread the word, and if you’re able to please consider helping out the Utahraptor Project on GoFundMe.

Unsolved Paleo Mysteries Month #13 – The Case of the Absent Archaeopteryx

One of the most famous of all fossil organisms, and a classic example of a transitional form, Archaeopteryx is currently known from 12 body fossil specimens.

Except one of them is missing.

The Maxberg specimen was part of the private collection of Eduard Opitsch, the owner of the Bavarian quarry where it was originally discovered in 1956. Despite being partially disintegrated, and missing its head and tail, it was still an immensely important discovery – at the time, it was only the third recognized Archaeopteryx ever found.

After briefly attempting to sell the new Archaeopteryx, Opitsch eventually allowed it to be held at the local Maxberg Museum. In 1974 he permitted casts to be made from it – but then suddenly removed it from public display and refused all further requests to access or study it.

(This may have been a reaction to the 1973 announcement of the more complete Eichstätt specimen. Opitsch, who was described as having “a difficult personality”, became increasingly defensive about the fossil, seeming to feel this new discovery was getting more attention and was deliberately devaluing his own.)

From then on the Maxberg specimen was lost to science.

When Opitsch died in 1991 his heir attempted to locate the fossil – it was rumored to be kept under his bed – but it was nowhere to be found. There’s some speculation that he was buried with it, literally taking his prized Archaeopteryx to the grave as a final act of spite. Another possibility is that it was stolen and sold in secret, perhaps to this day hidden away in a wealthy owner’s private collection.

It’s been missing for over 25 years, but there’s still lingering hope that the missing Maxberg specimen will one day resurface.

For now, though, all we have left are a few casts, photographs, and x-rays.

Unsolved Paleo Mysteries Month #04 – Who’s That Theropod?

In the early 1970s an opalized dinosaur leg bone in a South Australian gem shop came to the attention of paleontologist Neville Pledge. The specimen’s owner allowed it to be borrowed and studied, and it was eventually named as Kakuru kujani – Kakuru after the Rainbow Serpent of Australian Aboriginal mythology, and kujani after a variant spelling of the Guyani, the local indigenous people. Later the fossil was auctioned off to another private owner and lost to science for nearly 30 years, until finally being acquired by the South Australian Museum in 2004.

But all we really know about Kakuru is that it was some sort of theropod dinosaur. The 33cm (1′) tibia probably belonged to an animal up to about 2m long (6′6″), living during the Early Cretaceous (~125-112 mya), but any placement in a specific group is almost impossible. Based on particular features of the bone – such as a tall and narrow astragalar process – it’s been proposed to be either an oviraptorosaur or an abelisaur. But more recent examinations have concluded the bone’s preservation is too poor for those features to be confidently identified, and consider Kakuru to be a basal coelurosaur or even just a dubious name for an indeterminate theropod.

It’s all a bit of a mess, really, and more and better material is needed to clear up this mysterious dinosaur’s identity.

I’ve restored Kakuru here in three different ways, to illustrate just how varied the interpretations are – on the left, an early oviraptorosaur; in the middle, a generic coelurosaur; and on the right, an abelisaur.

(Yes, the abelisaur is fluffy. South Australia was within the Antarctic Circle during the Early Cretaceous, and while the climate there wasn’t as cold as it is today it was still chilly enough for some floofy insulation to be useful.)