How do we Know that Zhenyuanlong was Quite Big?

A few days ago, on July 16th, Everything Dinosaur team members published an article that featured the newly described Chinese dromaeosaurid dinosaur known as Zhenyuanlong suni.  We explained why the dinosaur called Velociraptor was used to help give this new dinosaur discovery context and outlined some of the more intriguing aspects of the fossil, that perhaps had been missed by more general media outlets.  However, we did receive an email about our article from a young dinosaur fan so we thought it best if we followed up our original article by providing some additional information about this little feathered carnivore.

To read our article (July 16th) on Z. suni: The Winged Dragon from Liaoning Province.

A Newly Described Dromaeosaurid from China

Very probably a ground-dwelling predator.

Picture credit: Zhao Chuang

Young Alex, wrote into Everything Dinosaur to ask, how do scientists know how big this dinosaur was and how big was it compared to other feathered dinosaurs found in China?  We wrote to Alex explaining in a little more detail about what the scientists who studied the fossil material concluded.

The academic paper describing this new type of “raptor” was published in the journal “Scientific Reports”.  The authors were Professor Junchang Lü (Institute of Geology, Chinese Academy of Geological Sciences, Beijing) and Dr Stephen Brusatte (School of GeoSciences, University of Edinburgh).

Early Cretaceous North-eastern China

Around 125 million years ago, the area of north-eastern China, now known as Liaoning Province was covered in a lush, temperate forest.  Large lakes featured in the environment and nearby volcanoes occasionally erupted and buried the area in fine ash, this explains the exceptional state of preservation of much of the Liaoning fossil material.

Living in the forests were a large number of different types of “raptor”, members of the Dromaeosauridae dinosaur family.  So far six genera have been described but it is very likely that more feathered dinosaur discoveries will be made in the future.

The six genera of dromaeosaurids described so far (with date described):

1. Sinornithosaurus (named in 1999)
2. Microraptor (named in 2000)
3. Graciliraptor (named in 2004)
4. Tianyuraptor (named in 2010
5. Changyuraptor (named in 2014)
6. Zhenyuanlong (2015)

So How Does Zhenyuanlong Compare?

The fossilised remains of Zhenyuanlong are nearly complete, but the end of the tail is missing.  The skeleton measures 126.6 cm long, when compared to the large dromaeosaurid Tianyuraptor it has been estimated that with the whole of the tail, this animal would have measured more than five feet (165 cm) in length.  It was probably not quite fully grown when it died so it might have reached a length of around 1.8 metres.

When it comes to comparing the sizes of different types of dinosaur, it is the limb bones that palaeontologists turn to.  The thigh bone (femur) for example, is often used to make comparisons between dinosaurs.  To estimate how big a dinosaur was, the length and the circumference of the femur is often measured.  In simple terms, the bigger and the more robust the femur, the bigger the dinosaur.

Comparing Other Dromaeosaurids to Zhenyuanlong suni

As all the Liaoning dromaeosaurid species discovered so far have at least one thigh bone as part of their fossil material, and as the size of the thigh bone strongly correlates to body size, measuring the length and overall size of the thigh bone is a useful way of comparing the sizes of different dinosaurs.

A Table Comparing the Femur Lengths and Overall Size of Liaoning Dromaeosaurids

Size comparisons between Liaoning dromaeosaurids.

Table credit: Everything Dinosaur

* Depends on the species and the specimens measured

** Depends on the species as there are three species of Microraptor currently known.

So based on the length of the thigh bone, scientists can see that Zhenyuanlong (Z. suni) is much bigger than most of the other dromaeosaurids known from Liaoning.  It seems to be about the size of Tianyuraptor.

What Does Zhenyuanlong suni Mean?

Time to answer one other question about this new dinosaur, this time sent in by Sophie.  Sophie asked what does Zhenyuanlong mean?

The Holotype Specimen of Zhenyuanlong suni

Large-bodied, short-armed Liaoning dromaeosaurid

Picture credit: Chinese Academy of Geological Science

Zhenyuanlong suni means “Mr Zhenyuan Sun’s dragon”.  The word “long” means dragon in Chinese (hence other dinosaur names such as Guanlong and Dilong) and the rest of the name honours Mr Zhenyuan Sun, who was able to acquire the holotype specimen for the scientists to study.

There is a spectacular modelof Zhenyuanlong in the Beasts of the Mesozoic model series: Beasts of the Mesozoic Figures and Models.

Zhenyuanlong – A Big Bird, well, Almost

This week we have seen the latest feathered and fluffy dinosaur revealed from the Lower Cretaceous deposits of Liaoning Province, north-eastern China.  Scientists from the University of Edinburgh including the very talented Dr Steve Brusatte, in collaboration with colleagues from the Institute of Geology (Chinese Academy of Geological Science, Beijing), have published a paper in the journal “Scientific Reports”, that describes Zhenyuanlong suni, the latest in an ever growing flock of feathered dinosaurs from Liaoning.

An Illustration of Zhenyuanlong suni

Very probably a ground-dwelling predator.

Picture credit: Zhao Chuang

A New Winged Dragon

We do understand why many of the media reports have focused on this Early Cretaceous dinosaur’s more famous relative – Velociraptor.  Dr Steve Brusatte of Edinburgh University’s School of GeoSciences refers to Velociraptor in interviews, although, Velociraptor and Zhenyuanlong (pronounced jen-won-long), are separated by some forty-five million years.  As Zhenyuanlong suni has been classified as member of the Dromaeosauridae family, it is indeed distantly related to the more famous Late Cretaceous “raptor”.  By discussing Velociraptor, it helps members of the public to put this new dinosaur into context.

Zhenyuanlong suni

Zhenyuanlong is most certainly not Velociraptor’s direct ancestor, but if these dinosaurs were feathered, then the point that Velociraptor, shown as a scaly-skinned reptile in dinosaur movies, is in all likelihood not being accurately depicted, is well made.  Although no evidence of feathers or any other integumental covering for that matter has been found in association with Velociraptor fossil material.  This has probably got more to do with the fossilisation process and the coarse sandstone matrix than any lack of feathers on Velociraptor’s part.

Velociraptor – Most Probably Feathered

Very probably feathered (V. mongoliensis and V. osmolskae)

Picture credit: Everything Dinosaur

Dromaeosaurid Models

The picture above shows the new for 2015, Velociraptor dinosaur model by Safari Ltd.  The model depicts Velociraptor as a dinosaur that was covered in a coat of feathers.  To view Everything Dinosaur’s range of Safari Ltd prehistoric animal models, including feathered dinosaur models: Feathered Dinosaur Models – Wild Safari Prehistoric World.

The Liaoning Dromaeosaurids – Now There are Six Genera

A total of six genera of dromaeosaurids are now known to have lived in the forests that once covered north-eastern China.  Several of these genera have more than one species associated with them and there are going to be more feathered dinosaurs described from the Yixian and Jiufotang Formations.  Everything Dinosaur team members will do their best to keep up to date with new discoveries and to write about them on this blog.

The six genera described to date:

1. Sinornithosaurus (named in 1999)
2. Microraptor (named in 2000)
3. Graciliraptor (named in 2004)
4. Tianyuraptor (named in 2010
5. Changyuraptor (named in 2014)
6. Zhenyuanlong (newly described)

Please don’t imagine all six of these dinosaurs roaming the forests that would have covered Liaoning Province about 125 million years ago, at the same time.  As the fossils come from different layers of strata, they are not all contemporaneous, in fact accurately dating Liaoning fossil material is known to be extremely tricky.  However, it is likely that many different types of feathered dinosaur co-existed and indeed many of them were specially adapted to a particular ecological niche.

The Holotype Fossil Material – Zhenyuanlong suni

Large-bodied, short-armed Liaoning dromaeosaurid

Picture credit: Chinese Academy of Geological Science

Examining the Type Specimen

The type specimen (pictured above), measures 126.6 cm in length, however, much of the tail is missing and this dinosaur was probably over 160 cm long.  This makes it one of the larger dromaeosaurids from Liaoning, the skull, although badly crushed reveals that this little dinosaur was carnivorous and a closer examination of the fossil revealed that it was covered in feathers, (pennaceous feathers = feathers with a central vane).  Pennaceous feathers are found in most modern birds, however, given the large body size and disproportionately small forelimbs when compared to other Liaoning domaeosaurids, it is unlikely that Zhenyuanlong was capable of powered flight.

Feathered Zhenyuanlong – Just Like a Big Bird

Our “feathered friend”.

Picture credit: Chinese Academy of Geological Science

The picture above shows, the complete holotype (A) with a close up of the posterior portion of the tail showing feather impressions (B), the skull and part of the forelimb (C), the right manus (hand) with extensive feathers (D) and (E) a close up of the ulna and radius (forearm) showing evidence of pennaceous feathers on this region of the body too.  Unlike other Liaoning dromaeosaurids, Graciliraptor and Microraptor for example, there is no evidence for feathers on the hind limbs.

Zhenyuanlong and Tianyuraptor

The describing of Zhenyuanlong does not just add to the diversity of dromaeosaurids known from China, it confirms the fact that short-armed dromaeosaurids were also covered in feathers too, just like their longer-limbed cousins.  There have been two basic Dromaeosauridae body plans (bauplans) described from the Jehol Biota.  Most of the Dromaeosauridae family members known from this part of the world had small bodies, with proportionately long forelimbs and accompanying broad wings covered in pennaceous feathers.  Then there is the other body plan, a much larger dinosaur with a heavier body and short arms.

Tianyuraptor (T. ostromi) was the only example known, until the discovery of Zhenyuanlong, but unlike Z. suni, the Tianyuraptor fossil specimen does not show any preserved evidence of feathers.

A Phylogenetic Analysis of Zhenyuanlong suni Amongst the Dromaeosauridae

The Liaoning dromaeosaurids nested within the Dromaeosauridae.

Picture credit: Chinese Academy of Geological Science with additional annotation by Everything Dinosaur

The “big bird” that is Zhenyuanlong although distantly related to Velociraptor (the Velociraptorinae sub-family), does suggest that more famous dinosaurs like Velociraptor were indeed probably feathered.

The Beasts of the Mesozoic model range contains a variety of raptors including Z. suni figures: Beasts of the Mesozoic Prehistoric Animal Figures.