Timurlengia – Important Addition to the Tyrannosaur Family Tree

Timurlengia, or to give the newest member of the tyrannosaur family tree its full, binomial scientific name Timurlengia euotica (pronounced Tee-mur-leng-gear-ah oo-ot-tick-ah) has been introduced to the world.  Lots of media coverage for this, the latest member of the tyrannosaur super-family, the Tyrannosauroidea and in this article, rather than go over old ground, we shall instead focus on some of the more significant aspects of this particular piece of fascinating research.

Tyrannosaur Fossil

Timurlengia Roaming a Late Cretaceous Flood Plain

The tyrannosaurid Timurlengia wandering its flood plain home.

Picture credit: Todd Marshall

The illustration of Timurlengia above, depicts this tyrannosaur as a light and agile animal, weight estimates vary (170 to 250 kilogrammes), but note also that this dinosaur has been given a shaggy coat.  There is evidence to suggest that at least some tyrannosaurids may have been feathered, these days, depicting a feathery theropod is becoming the norm.  Soaring overhead are two pterosaurs, the species is Azhdarcho longicollis and those white objects in the background that can be seen just below and just above the long tail of Timurlengia are primitive birds.

Uzbekistan might not spring to mind when asked to name a famous fossil-rich part of the world that represents life in the Late Cretaceous, but strata in the Kyzyl Kum Desert represent one of the few places in the world where an insight into life on our planet some ninety million years ago can be obtained.

The Significance of the Bissekty Formation

The fossil material, representing less than five percent of the entire skeleton, comes from exposed strata dating from the early Late Cretaceous.  These rocks are part of the Bissekty Formation of the Kyzyl Kum Desert (Uzbekistan).  The Formation dates from 90 to 85 million years ago, a number of vertebrate fossils including many different types of dinosaur have been found in these rocks.  The sediments indicate a low-lying coastal environment that was crossed by a number of large and highly braided river channels.  The Timurlengia fossil material is believed to date from approximately 90 million years ago (Turonian faunal stage of the Late Cretaceous).

The Fossil Material T. euotica

Timurlengia fossils.

Picture credit: Proceedings of the National Academy of Sciences

The picture above shows the amount of fossil material collected, crucially the pieces of jaw and the isolated teeth are typical of a tyrannosaurid.  Described as being “the size of a horse”, Timurlengia is very typical in terms of its build and its size with regards to Late Jurassic and Early/Middle to early Late Cretaceous tyrannosaurids.  However, what has puzzled palaeontologists is this, throughout the majority of the long lineage of the tyrannosaurs these animals probably filled secondary predatory niches in food chains.

Despite their wide geographical distribution, it was only towards the end of the Cretaceous that these types of theropod dinosaur started to evolve into the myriad of apex predators we know today.  Could Timurlengia provide evidence to support how and why the likes of Tyrannosaurus rex, became so huge and dominant?

Filling a Twenty Million Year Gap

Significantly, the rocks that contained the Timurlengia fossils have been dated to, what might have been a key point in tyrannosaurid evolution.  These fossils come from a time just about ten million years or so before the tyrannosaurs began to evolve great size.  Tyrannosaurus rex, that most famous of all dinosaurs, was something like thirty times heavier for example, studying the Timurlengia fossils could provide clues as to why after tens of millions of years of being relatively small, did these particular meat-eaters become super-sized.

 The Authors of the Scientific Paper Plotted the Position of Timurlengia in the Tyrannosaur Family Tree

Timurlengia placed into context with other tyrannosaurids.

Picture credit: Proceedings of the National Academy of Sciences

The picture above shows a tyrannosaur family tree, the position of Timurlengia euotica is outlined in red.  This dinosaur’s phylogenetic relationship with earlier and the later much larger tyrannosaurids is outlined, along with the location of fossil discoveries and a geological time scale.

Key to Tyrannosaur Fossil Locations

Red = Asia (including Uzbekistan)

Blue = Western North America (Laramidia)

Yellow = Eastern North America (Appalachia)

Pink = Europe

Studying the Braincase – Obtaining Information about Tyrannosaur Senses

The fossils used in the study were collected by Dr Hans Dieter Sues (Chair, Department of Palaeobiology, National Museum of Natural History, Smithsonian Institution ) and his colleague Alexander Averianov from the Russian Academy of Sciences over a ten year period. It was when the partial braincase was identified and analysed using a CT scanner that the link between this tyrannosaur and its more illustrious and later relatives became established.

CT Scans

The detailed CT scans revealed that although Timurlengia was not that big, about the size of other Cretaceous tyrannosaurids, it did possess a highly sophisticated brain and its inner ear was very reminiscent to the features of the inner ear found in Late Cretaceous tyrannosaur giants.    This suggests that Timurlengia had very sharp senses including great hearing, particularly at low frequencies, could this have give this predator a competitive advantage?

The Partial Braincase (top) and the CT Scan Evidence (bottom)

The braincase of Timurlengia and data from the CT scan showing brain and inner ear shape.

Picture credit: Proceedings of the National Academy of Sciences

A Partial Braincase

The partial braincase was actually discovered back in 2004, but it has remained unexamined and in storage at the Zoological Institute of the Russian Academy of Sciences until palaeontologist Steve Brusatte (Edinburgh University) was given the chance to study the fossil.  He realised the importance of this specimen, the CT scans showed that Timurlengia had long inner ear canals, ideal for hearing a range of sounds especially low frequency noises and this research has led to the subsequent paper being published in the Proceedings of the National Academy of Sciences.

The picture above shows three views of the partial braincase of Timurlengia euotica (posterior view, ventral view and right lateral view).  The bottom row of images are composite pictures from the various CT scans.  The brain is stained dark blue, the inner ear is pink, nerves highlighted in yellow and major blood vessels are coloured red.  This study suggests that the tyrannosauroids apparently developed huge size rapidly during the latest Cretaceous, and their success in the top predator role may have been enabled by their brain and keen senses that first evolved at smaller body size.

Dr Sues commented:

“This fossil shows that tyrannosaurs developed their advanced head first.  Timurlengia’s skull, though much smaller than that of T. rex, shows a sophisticated brain that would have led to keen eyesight, smell and hearing.”

The genus name honours the Asian warlord Timur (also known as Tamerlane), the trivial name means “well-eared” a direct reference to this dinosaur’s hearing capabilities.

Not the Entire Story

Having very well developed senses would have greatly assisted the tyrannosaurids, but this in itself does not explain how these theropods rose to dominance towards the end of the Mesozoic.  There were, in all likelihood, a number of other factors involved.  For example, bigger predatory dinosaurs would have had to have gone into decline and probably become extinct to permit the tyrannosaurids to exploit the vacuum left in the food chain.

The reason for the decline of other predators remains unclear.  As far as we aware, despite the abundance of vertebrate fossil material associated with the Bissekty Formation, no very large theropod fossils have been found to date.  If there was an apex predator or predators sharing this environment, then the identity of these dinosaurs remains unknown.

Carcharodontosauridae Decline

World-wide many of the apex dinosaur predators known to have existed around 100 to 90 million years ago are representatives of the Carcharodontosauridae.  This family of theropods, which includes such iconic giants such as Acrocanthosaurus (United States), Sauroniops (Morocco) and Carcharodontosaurus (North Africa), did decline and did eventually become extinct, but studies have shown that these predators too, also possessed sophisticated senses.  Perhaps the evolution of different types of prey triggered this “changing of the guard”, this in turn, could have been influenced by the rise of the angiosperms (flowering plants).

Tyrannosaurs may be iconic dinosaurs but there is much about their long history that we still do not understand.  Timurlengia along with future fossil finds will help to shed more light on this palaeontological puzzle.

A Close up View of a Tooth Assigned to Timurlengia

View of the left and right side of a Timurlengia tooth.

Picture credit: James Di Loreto, Smithsonian Institution

Last month, Everything Dinosaur reported on a new study into the tyrannosaur family tree by Steve Brusatte and colleagues.  This was a re-assessment of an earlier piece of research (2010), the phylogeny of tyrannosaurids being updated as a result of recent fossil finds.

To read this article: An Update on the Evolution of Tyrannosaurs.

New Reptile Species “Just before the Dinosaurs”

The academic journal “Scientific Reports” published today contains a paper detailing the discovery of a remarkably well preserved fossil reptile, one that existed not long after the End Permian mass extinction event.  The fossil, an amazing and nearly complete skull described by the scientists as “extraordinary” plus some cervical vertebrae (neck bones) provides an important link between primitive reptiles and the Archosauriforms that gave rise to modern crocodiles, the Pterosauria, Aves and of course the dinosaurs.

Fossil Reptile Discovery

The 1.5-metre-long reptile, probably filled an ecological niche similar to today’s smaller crocodile species.  Ambushing smaller vertebrates as they came down to the water’s edge to drink.  It may also have hunted amphibians and fish in the shallows.  Named Teyujagua paradoxa the fossil material comes from the Sanga do Cabral Formation located in the Brazilian State of Rio Grande do Sul in the far south of the country.

The Skull of Teyujagua paradoxa

Scale bar = 5 centimetres.

Picture credit: Scientific Reports

The picture above shows three views of the “extraordinary” skull right lateral view (top), dorsal view (middle) and left lateral view (bottom).  Scale bar equals five centimetres.

“Fierce Lizard”

The fossil material was discovered early last year by a field team from the Paleobiology Laboratory of the Universidade Federal do Pampa (Brazil), the genus name means “fierce lizard” in the local dialect of the  Guarani, a name inspired by a mythological and magical beast called Teyú Yaguá.  The species name “paradoxa”, from the Greek for paradox or unexpected, denotes the fact that the fossils show an unusual combination of primitive and more advanced, derived characteristics.

An Illustration of Skull of “Fierce Lizard” Teyujagua paradoxa

Teyujagua skull drawing (right lateral view).

Picture credit: Scientific Reports

The teeth particularly those of the maxilla are large, serrated and curved, the teeth of a carnivore.  The large orbit (eye socket) and the position of the nostrils suggest that this animal could lie in wait for prey under water with only its nostrils above the surface of the water, a typical predatory strategy adopted by many crocodiles today.

Living After the Permian-Triassic Extinction Event

The authors of the report state that this fossil find is significant as Teyujagua lived just after the Permian-Triassic extinction event, a mass extinction event that wiped out 90% of all terrestrial vertebrates.  Teyujagua provides new insights into how ecosystems on land recovered and developed following this extinction.  After the extinction, terrestrial ecosystems were sparsely populated, providing opportunities for some groups of survivors to expand in number and diversity.  Archosauriforms and their close kin like Teyujagua became the dominant animals in terrestrial habitats, eventually giving rise to the Dinosauria.

An Artist’s Reconstruction of Teyujagua

A 250-million-year-old reptile.

Picture credit: Voltaire Neto

An Exciting Discovery

Dr Felipe Pinheiro, from Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul and the corresponding author for the scientific paper stated:

‘The discovery of Teyujagua was really exciting.  Ever since we saw that beautiful skull for the first time in the field, still mostly covered by rock, we knew we had something extraordinary in our hands.  Back in the lab, after slowly exposing the bones, the fossil exceeded our expectations.  It had a combination of features never seen before, indicating the unique position of Teyujagua in the evolutionary tree of an important group of vertebrates.’

Although, it is difficult to precisely date the Sanga do Cabral Formation, the fossils have been dated based on faunal comparisons with the Karoo Basin deposits of South Africa.  The scientists infer that Teyujagua dates from the Induan to the early Olenekian faunal stage of the Early Triassic (around 251-249 million years ago).

More Tetrapod Fossils Found

Along with the skull and cervical vertebrae of T. paradoxa, the field team excavated fossil material associated with the parareptile Procolophon trigoniceps along with temnospondyl amphibians and a number of as yet unidentified tetrapod bones.

Dr Richard Butler, from the University of Birmingham’s School of Geography, Earth and Environmental Sciences, who also co-authored the scientific paper commented:

‘Teyujagua is a really important discovery because it helps us understand the origins of a group of vertebrates called archosauriforms.  Archosauriforms are spectacularly diverse and include everything from hummingbirds and crocodiles to giant dinosaurs like Tyrannosaurus rex and Brachiosaurus.  Teyujagua fills an evolutionary gap between archosauriforms and more primitive reptiles and helps us understand how the archosauriform skull first evolved.”

The Teyujagua quarry is still being excavated and the researchers are confident that they will find more Teyujagua fossil material along with some more, and perhaps equally “extraordinary” tetrapods.

Chemical Analysis to Identify Medullary Bone in the Dinosauria

Chemical analysis to help identify medullary bone preserved in the femur of a Tyrannosaurus rex from the Museum of the Rockies may help scientists to probe deeper into the evolutionary relationship between living archosaurs (birds and crocodiles) and their extinct near relatives the Dinosauria.  Using a chemical test to identify the tell-tale traces of keratan sulphate (a long-chain, complex molecule), a component unique to medullary bone, scientists may be able to shed more light on the evolution of egg laying in extant Aves (birds) as well as having the handy side-effect of being able to tell the girl dinosaurs from the boys.

An Illustration of a Gravid Tyrannosaurus rex

An illustration of a gravid T. rex. Medullary bone chemical analysis provides new data on egg laying evolution.

Picture credit: Mark Hallett

Dinosaur Thigh Bone Studied

Researchers from North Carolina State University and the North Carolina Museum of Natural Sciences have confirmed the presence of medullary bone in the thigh bone of a Tyrannosaurus rex from Montana.  Amongst the scientists who authored a paper on this study, is Dr Mary Schweitzer (Department of Biological Sciences, North Carolina State University), who has caused much scientific controversy over her research into the possibility of recovering organic remains from long extinct creatures.

For example, last December Everything Dinosaur reported on a remarkable piece of research that provided evidence of the preservation of blood vessels within the fossilised bones of a duck-billed dinosaur.  To read about this fascinating study: Duck-billed Dinosaur Blood.

The Importance of Medullary Bone

Medullary bone is laid down within the bones of female birds immediate prior to or during the egg laying period.  Medullary bone has been detected in virtually all extant bird species (with the possible exception of some passerines).  The bone is produced quickly and provides a mobile source of calcium for the building of egg shells.  The easy to identify bone (it has a very different internal structure compared to other bone types and tends to be less dense), has a high preservation potential within the fossil record due to the high levels of the mineral calcium within the bone tissue.

Medullary bone has not been detected in those other near dinosaur relatives the crocodilians.  This suggests that the ability build up a reserve of calcium for egg-laying and to rapidly reabsorb the minerals once the reproductive need had been met, evolved in the Avemetatarsalia, one of two clades into which all archosaurs are classified.  The Avemetatarsalia include modern birds and dinosaurs, the other archosaur clade (Crurotarsi) includes the crocodilians, it can be suggested that in the Crurotarsi medullary bone did not evolve.

As dinosaurs also laid eggs, then if medullary bone-like material is preserved in the fossil record then it can be deduced that those bone fossils that contain physical evidence of this specialised bone must represent females.

Chemical Analysis Supports Earlier Findings

Back in 2005, Dr Schweitzer published a paper describing the research into medullary bone found in a 68- million-year-old partial T. rex femur (MOR 1125).  However, her findings were not entirely accepted by the majority of the scientific community.

Dr Schweitzer explained:

“All the evidence we had at the time pointed to this tissue being medullary bone, but there are some bone diseases that occur in birds, like osteopetrosis, that can mimic the appearance of medullary bone under the microscope. So to be sure we needed to do chemical analysis of the tissue.”

If the physical evidence could be backed up by further testing to identify without doubt medullary bone then that would be a great step forward.  These researchers have taken up this challenge and using monoclonal antibodies they have identified a chemical signature that relates to the presence of keratan sulphate within the fossil material.

Comparative Tests Using Extant Archosaurs (Birds)

It had been previously thought that none of the original chemistry of dinosaur bone would survive millions of years.  However, comparative tests using known medullary tissue from ostriches and chickens confirmed their analysis.  The team conclude that the tissue from the femur of a Tyrannosaurus rex is indeed medullary bone.

CT Scan Images of Femur (MOR 1125) Showing Differences Between Medullary (MB) and Cortical Bone (CB)

Medullary bone identified in Tyrannosaurus rex femur.

Picture credit: Scientific Reports

The picture above shows various CT scans of the femur bone from the study.  Medullary bone is identified as MB, the denser cortical bone (CB) is also shown.  A-D are volumetric readings, whilst E-G show cross sections.  In pictures A and B, the high density cortical bone is rendered transparent to show the lower density medullary bone material.  Picture E shows the density as a spectrum from high density (black) to low density (white).  The bone fragment is (C, D and G) colour mapped and (F) heat mapped.  Colour mapping key: (C, D, G)  medullary bone equals orange/red and cortical bone is beige/yellow.  Heat mapping key (F) highest density is red, lowest density blue.  The sample shown in A, C, E-G is shown in cross sectional view, whereas B and D are medial views.

A Window into the Evolution of Egg Laying

Dr Schweitzer added:

“This analysis allows us to determine the gender of this fossil, and gives us a window into the evolution of egg laying in modern birds.”

It might be very difficult to find further examples of medullary bone for this type of chemical analysis in the tyrannosaurid fossil record as the transitional nature of medullary bone means that animals would only possess this type of bone within their bodies for very short periods.  However, Everything Dinosaur has reported on the finding of physical evidence to support gender identification in the Dinosauria before.

For example, in 2011 Everything Dinosaur reported on a study led by British scientists using the fossilised bones of a stegosaur (Kentrosaurus) to establish dinosaur genders.

To read more about this research: Telling the Girl Dinosaurs from the Boys.

The femur was already broken when the team from North Carolina State University and the North Carolina Museum of Natural Sciences set about their study and most palaeontologists would not want to cut open or demineralise fossils to search for rare medullary bone, however, the ability to conduct CT scans to examine internal fossil structures would greatly improve the chances of success without having to damage the fossil material.

This new chemical detection method may help to split the girl dinosaurs from the boys.

For models of Tyrannosaurus rex and other archosaurs: Wild Safari Dinosaur and Prehistoric Animal Figures.