A FEATHERED Dinosaur Tail Found Trapped in Amber From Cenomanian Cretaceous Myanmar

A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber

Authors:

Xi et al

Abstract:

In the two decades since the discovery of feathered dinosaurs, the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution. However, three-dimensional feather morphology and evolutionary patterns remain difficult to interpret, due to compression in sedimentary rocks. Recent discoveries in Cretaceous amber from Canada, France, Japan, Lebanon, Myanmar, and the United States reveal much finer levels of structural detail, but taxonomic placement is uncertain because plumage is rarely associated with identifiable skeletal material. Here we describe the feathered tail of a non-avialan theropod preserved in mid-Cretaceous (∼99 Ma) amber from Kachin State, Myanmar, with plumage structure that directly informs the evolutionary developmental pathway of feathers. This specimen provides an opportunity to document pristine feathers in direct association with a putative juvenile coelurosaur, preserving fine morphological details, including the spatial arrangement of follicles and feathers on the body, and micrometer-scale features of the plumage. Many feathers exhibit a short, slender rachis with alternating barbs and a uniform series of contiguous barbules, supporting the developmental hypothesis that barbs already possessed barbules when they fused to form the rachis. Beneath the feathers, carbonized soft tissues offer a glimpse of preservational potential and history for the inclusion; abundant Fe2+ suggests that vestiges of primary hemoglobin and ferritin remain trapped within the tail. The new finding highlights the unique preservation potential of amber for understanding the morphology and evolution of coelurosaurian integumentary structures.

Pycnonemosaurus nevesi is the new King Abelisauroid Theropod

Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king

Authors:

Grillo et al

Abstract:

Abelisauroid dinosaurs normally reached an average body length (BL) of 5–9 m, but there are controversies due to the incomplete or fragmentary nature of most specimens. For Ekrixinatosaurus, for example, BL was estimated as 10–11 m or 7–8 m; for Pycnonemosaurus it was proposed 7–8 m, however its preserved bones are larger than any other described abelisauroid. The lack of a consistent methodology complicates comparisons of estimated BL, so we reevaluated the estimative for the seven most complete specimens of abelisauroids and compared the values against 40 measurements from the skull, vertebrae and appendicular elements using bivariate equations. It allowed estimating the BL of other 30, less complete, specimens of abelisauroids and to evaluate the allometric scaling of the skeletal parts. Strong correlations (R2 > 0.96) were obtained for all vertebrae and hindlimb measurements, as well as skull height, and length of skull roof, lacrimal–squamosal, scapulocoracoid and humerus; other skull and forelimb measurements present weak correlation due to extreme morphological transformations observed in Abelisauridae and were not adequate for BL estimation. Abelisauroids gradually increased in size during evolution: the mean BL was 3.3 ± 2.5 m for basal abelisauroids and Noasauridae, 5.4 ± 1.8 m for basal Brachyrostra and Majungasauridae, and 7.1 ± 2.1 m for Furileusaura. Despite this variation, diversity of BL on each geographic region and stratigraphic epoch was relatively constant (BL usually varied from 4 to 8 m). The smallest noasaurid and abelisaurid are, respectively, Velocisaurus (1.5 ± 0.1 m) and Genusaurus (3.6 ± 0.0 m). The largest abelisaurids is Pycnonemosaurus nevesi (8.9 ± 0.3 m) followed by Carnotaurus (7.8 ± 0.3 m), Abelisaurus (7.4 ± 0.7 m) and Ekrixinatosaurus (7.4 ± 0.8 m). Skull measurement scale negatively at a similar rate but the height scales almost isometrically and the skull roof length scales more negatively; this probably caused a bending on the skull that may explain the upward orientation of the snout in large taxa.

Wiehenvenator albati (aka the Monster von Minden): a new Megalosaurid Theropod From Callovian Jurassic Germany

A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: implications for theropod evolution and faunal turnover in the Jurassic

Authors:

Rauhut et al

Abstract:

Fragmentary remains of a large, robustly built theropod dinosaur were recovered from the marine middle Callovian Ornatenton Formation of north-eastern Northrhine-Westphalia, Germany. The specimen includes a premaxilla, maxilla, lacrimal, postorbital, dentary, several caudal vertebrae, ribs, fibulae, astragalus, and partial calcaneum. It is here described as a new species of megalosauroid, Wiehenvenator albati n. gen. n. sp., diagnosed by a strongly reduced maxillary antorbital fossa on the base of the ascending process of the maxilla, a very short anterior ramus of the lacrimal with an additional pneumatic depression anteroventral to the lacrimal fenestra, a transversely expanded orbital facet in the postorbital, and a laterally flexed proximal end of the ascending process of the astragalus. Phylogenetic analysis recovers Wiehenvenator as a megalosaurine megalosaurid, sister taxon to the Late Jurassic genus Torvosaurus. It thus adds to the considerable diversity of megalosauroids in the Middle Jurassic. A time-calibrated phylogeny of theropods indicates a rapid radiation of averostran theropods between the Toarcian and the Bathonian. This radiation was probably triggered by the Pliensbachian-Toarcian extinction event, which might have been more important for theropod evolution than the Triassic-Jurassic extinction. The fossil record indicates a faunal turnover from megalosauroid dominated Middle Jurassic to allosauroid / coelurosaur dominated Late Jurassic faunas. However, differences in the Middle and Late Jurassic theropod fossil records both in respect to geographic distribution of localities, as well as sampled environments make this inference problematic, at least in respect to allosauroids. An analysis of environmental preferences of allosauroids and megalosauroids indicates that the former preferred inland environments, whereas the latter are more common in nearshore environments.

Tracing the Origin & Evolution of Bird Reproduction in Dinosaurs

What really did come first--the chicken or the egg? Birds' reproductive biology is dramatically different from that of any other living vertebrates, and ornithologists and paleontologists have long wondered how and when the unique features of bird reproduction originated. A new Review in The Auk: Ornithological Advances examines answers from three sources--modern birds, fossils of primitive birds, and fossils of the dinosaurs from which birds are descended--to shed new light on the subject.

All modern birds share certain reproductive features, such as a single functional ovary and the practice of incubating their eggs through direct contact. Analysis of the bird family tree also suggests that early birds built simple, open nests on the ground and that their young were "precocial," meaning they were well-developed and almost ready to fend for themselves when they hatched. Those dinosaurs close to the ancestry of birds shared some of these traits, but they had two functional reproductive tracts, and their eggs were smaller relative to their body size and more elongated than those of modern birds.

Fossils of primitive birds and eggs from the Mesozoic era place them midway between their dinosaur ancestors and their modern descendants, with eggs between those of pre-avian dinosaurs and modern birds in term of size and shape. In this way, David Varricchio and Frankie Jackson of the Montana State University are able to trace the evolution of bird reproduction through a series of distinct stages, from pre-avian dinosaurs to the birds of today.

link.

A Giant Abelisaurus Theropod Foot Print Found in Bolivia

A footprint measuring over a metre wide has been discovered in the southern American country of Bolivia. It's thought to have been made by an Abelisaurus, a meat-eating dinosaur that walked the Earth millions of years ago. Palaeontologist Sebastian Apesteguia went to the site of the discovery.

link.

Cenozoic Theropod Dinosaurs in South America Revisited

Cenozoic dinosaurs in South America – revisited

Authors:

Molnar et al

Abstract:

Of course there were Cenozoic dinosaurs (theropods) in South America, phorusrhacid (‘terror’) birds among others, but that is not the subject here. Why did anyone think there were Cenozoic (non-avian) theropods in South America? Because of a misinterpretation of Ameghino’s belief that derived mammals lived along with dinosaurs in Late Cretaceous Argentina. But also because isolated theropod teeth were found associated with derived (Eocene) mammal fossils. These turned out to be the teeth of Sebecus icaeorhinus. This is a small crocodylomorph, skull length c. 450 mm. More recently discovered sebecosuchians were substantially larger: Barinasuchus arveloi had an (estimated) skull length of c. 1000 mm, similar to that of Daspletosaurus (1000 mm). These crocodylomorphs are generally believed to have been terrestrial animals, presumably preying on large mammals. Thus, although there were no large non-avian theropods in Cenozoic South America, there were crocodylomorphs that seem to have been ecological vicars of large theropods. The reconstruction of terrestrial trophic networks for large terrestrial tetrapods after the Cretaceous-Paleogene extinctions seems to have been slower than often supposed. At (or near) the Cretaceous-Paleogene boundary, large herbivores turned over from archosaurs to mammals, but turnover of large carnivores was slower. In South America, dinosaur-size crocodylomorphs lived as late as the Miocene. Thus modern terrestrial ecosystems do not, trophically, reflect those of even the Early Neogene in some southern continents. Sebecosuchians, at least in South America, seem to have been unaffected by the Cretaceous-Paleogene extinctions.

Murusraptor barrosaensis: a new megaraptorid Theropod From Cretaceous Argentina

A new species of megaraptorid dinosaur discovered in Patagonia may help discern the evolutionary origins of the megaraptorid clade, according to a study published July 20, 2016 in the open-access journal PLOS ONE by Rodolfo Coria from the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, and Phillip Currie from the University of Alberta, Canada.

The Patagonian region of Argentina has previously proven to be rich in fossils from the Late Cretaceous epoch, including a number of megaraptorids, a clade whose carnivorous diet gave rise to their name meaning 'giant thieves'. These medium-sized theropod dinosaurs, including South American genera Megaraptor, Orkoraptor, and Aerosteon as well as genera from Australia and Japan, have characteristically large claws and air-filled, birdlike bones.

The fossilized partial skeleton of a megaraptorid dinosaur analyzed in this study was discovered in Sierra Barrosa, in northwest Patagonia and represents one of the most complete megaraptorids found, with an unusually intact braincase. With unique skull features, the dinosaur, which they named Murusraptor barrosaensis, is a new species in the megaraptorid clade. This specimen appears to be immature, but the authors suggest that the species is larger and slenderer than Megaraptor and comparable in size with Aerosteon and Orkoraptor. While sharing many features with the other species, Musuraptor has distinctive facial features not previously seen amongst megaraptorids, as well as unusually shaped hip bones.

While phylogenetic analysis could not clearly determine evolutionary relationships, the authors note that these fossils provide new anatomical information which might help to resolve current debates as to whether the megaraptorids are a clade of the allosauroid or the coelurosaurid theropods.

link.

paper link.

Gualicho shinyae: a Neovenatorid Carcharodontosaurian Theropod With a Tyrannosaur-like Hand From Cenomanian Cretaceous Argentina

An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina

Authors:

Apesteguía et al

Abstract:

Background

Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit.

Methodology/ Principal Findings

A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton.

Conclusions/ Significance

Gualicho shinyae gen. et sp. nov. increases the known theropod diversity of the Huincul Formation and also represents the first likely neovenatorid from this unit. It is the most basal tetatanuran to exhibit common patterns of digit III reduction that evolved independently in a number of other tetanuran lineages. A close relationship with Deltadromaeus from the Kem Kem beds of Niger adds to the already considerable biogeographic similarity between the Huincul Formation and coeval rock units in North Africa.

pop sci write up.

Tetrapod Zoology Continues With Part III on the Maniraptors

Welcome to the third article in the series on trends and tendencies in non-bird maniraptoran evolution (part 1 is here, part 2 is here). In previous articles we looked at the position of maniraptorans within the theropod radiation, and at the main maniraptoran groups. You’ll need to have remembered most of the relevant group names for the following to make sense… though, if you haven’t, I wouldn’t worry about it much, I’m sure it’ll work out.

link.

A new Microraptor Relative Found in Cretaceous China?

A new microraptorine specimen (Theropoda: Dromaeosauridae) with a brief comment on the evolution of compound bones in theropods

Authors:

Xu et al

Abstract:

Microraptorinae is a recently discovered subgroup of dromaeosaurid theropods, mostly comprising species from the Lower Cretaceous Jehol Group of western Liaoning, China. Here we describe a new microraptorine specimen from the Jiufotang Formation (the upper section of the Jehol Group) of Dapingfang, Chaoyang, Liaoning, which displays interesting morphological features not previously documented within Microraptorinae. Noteworthy are several osteological features, including dental and ischial ones, which are transitional between the condition of Sinornithosaurus and that of Microraptor. These features highlight the existence of a spectrum of morphological variation between Sinornithosaurus, which is more like a typical dromaeosaurid, and Microraptor, which shares many characteristics with troodontids. However, the taxonomic significance of these variations has not to be fully assessed yet. A feature deserving special mention is the fusion of the pubes to the ilia in this specimen, which has implications for the evolution of compound bones in theropods+. Our preliminary analysis suggests that many compound bones in birds have been formed by sequential fusion of multiple elements in a peramorphic process.

Small scale scrapes suggest avian display behavior by diminutive Cretaceous theropods

Small scale scrapes suggest avian display behavior by diminutive Cretaceous theropods

Authors:

Kim et al

Abstract:

A set of about 25 diminutive sub-parallel scrapes in the Cretaceous Haman Formation of South Korea fit the morphology of the small theropod track Minisauripus which is also known from this formation. The scrapes are interpreted as evidence of display behavior, and suggest that the trace maker was an adult engaged in avian-like courtship behavior. Although avian theropods are also known from this formation, the scrapes are inconsistent with their foot morphology. Although large theropod scrapes have been interpreted as evidence of display behavior they are only known from North America. Thus, the scrapes described here are the first reported from Asia, and the first interpreted as evidence of display behavior in such a diminutive species.

Tetrapod Zoology on The Maniraptor Dinosaurs Part 2

In this second article on maniraptorans, we look at the main groups that constitute this clade: you’ll need to remember the main group names if the trends and tendencies discussed in later parts of this series are to make any sense. The previous article – part 1 – looked briefly at maniraptoran origins and at the fact that maniraptorans are nested within coelurosaurian theropods. Ok, onwards…

link.

Small Theropod Dinosaurs Scraped out Display Areas Like Birds

Small scale scrapes suggest avian display behavior by diminutive Cretaceous theropods

Authors:

Kim et al

Abstract:

A set of about 25 diminutive sub-parallel scrapes in the Cretaceous Haman Formation of South Korea fit the morphology of the small theropod track Minisauripus which is also known from this formation. The scrapes are interpreted as evidence of display behavior, and suggest that the trace maker was an adult engaged in avian-like courtship behavior. Although avian theropods are also known from this formation, the scrapes are inconsistent with their foot morphology. Although large theropod scrapes have been interpreted as evidence of display behavior they are only known from North America. Thus, the scrapes described here are the first reported from Asia, and the first interpreted as evidence of display behavior in such a diminutive species.

Elaphrosaurus bambergi: a Reevaluated Noasaurid Abelisauroid From Late Jurassic Tanzania

The theropod dinosaur Elaphrosaurus bambergi Janensch, 1920, from the Late Jurassic of Tendaguru, Tanzania

Authors:

Rauhaut et al

Abstract:

Theropod dinosaurs from the Late Jurassic of Gondwana are still poorly known, with Elaphrosaurus bambergi Janensch, 1920, from the late Kimmeridgian of Tendaguru, Tanzania, being the only taxon represented by more than isolated remains from Africa. Having long been considered a coelurosaurian, more specifically an ornithomimosaur, Elaphrosaurus is currently regarded as a basal ceratosaur. Here, we revise the osteology and phylogenetic position of this important taxon. Elaphrosaurus shows many unusual osteological characters, including extremely elongated and constricted cervical vertebrae, an expansive shoulder girdle with strongly modified forelimbs, a relatively small ilium, and elongate hindlimbs with a very small ascending process of the astragalus that is fused to the tibia. We found this taxon to share many derived characters with noasaurids, such as: strongly elongate cervical and dorsal vertebrae; low, rectangular neural spines in the mid-caudal vertebrae; presence of only an anterior centrodiapophyseal lamina in anterior caudal vertebrae; presence of a wide, U–shaped notch between the glenoid and the anteroventral hook in the coracoid; a laterally flared postacetabular blade of the ilium; a flat anterior side of the distal tibia; and a reduced shaft of metatarsal II. Our analysis placed Elaphrosaurus within a dichotomous Noasauridae as part of a Jurassic subclade, here termed Elaphrosaurinae, that otherwise includes taxa from eastern Asia. These results underscore the long and complex evolutionary history of abelisauroids, which is still only beginning to be understood.

Theropods Were Also Good Scavengers

When asked to think of meat-eating dinosaurs we usually conjure images of voracious predators chasing down helpless prey. These visions are no doubt inspired by the depiction of species such as Tyrannosaurs rex and Velociraptor in the movie Jurassic Park; however, new research conducted at Trinity College Dublin suggests that many of these species might be better remembered as oversized, scaly or feathered hyenas.

This is because Irish and Scottish researchers have now shown that scavenging would have been a particularly rewarding strategy for some carnivorous dinosaurs.

Most predators rely on scavenging (feeding on already dead material) to meet their energetic needs; for example, even lions scavenge up to nearly 50% of their food in some populations. Unlike lions though, meat-eating dinosaurs ranged from the chicken-sized to the whale-sized and lived in environments that featured prey that were often larger still.

By using computer simulations to create models of the Mesozoic environments in which these meat-eating dinosaurs lived (think of a prehistoric Pacman searching his maze for food, or a Dino-themed version of The Sims), the researchers found that species weighing around half a tonne would have been the most efficient scavengers.

Dinos that slotted into this niche included juvenile T. rexes and mid-sized species such as Dilophosaurus and Utahraptor.

Research Fellow in Trinity's School of Natural Sciences, and co-lead author, Dr Kevin Healy, said: "In effect, these species occupied a Goldilocks zone. They were big enough to search large areas in order to find carcasses and defend them, but not so large that simply moving became too energetically costly."

link.

Apatoraptor pennatus: a new Caenagnathid Oviraptorosaur From Cretaceous Canada

A new caenagnathid (Dinosauria: Oviraptorosauria) from the Horseshoe Canyon Formation of Alberta, Canada, and a reevaluation of the relationships of Caenagnathidae

Authors:

Funston et al

Abstract:

Our understanding of caenagnathids has benefited from recent discoveries, including nearly complete skeletons from the Hell Creek Formation of Montana. However, their phylogenetic relationships remain unclear. A new specimen from the Horseshoe Canyon Formation of Alberta has implications for the phylogeny and paleobiology of these creatures. The partial skeleton is articulated and includes a mandible, a full cervical and dorsal series of vertebrae, a right pectoral girdle and arm, a sternum, gastralia, a partial ilium, and a partial hind limb. The mandible is edentulous and the articular ridge is intermediate in form between Caenagnathus collinsi and Chirostenotes pergracilis. The neck is long and composed of at least 11 well-pneumatized cervical vertebrae with fused cervical ribs. The dorsal ribs have finger-like uncinate processes dissimilar in shape to those of other oviraptorosaurs. The pectoral girdle is large and typically maniraptoran, except that the glenoid of the scapulocoracoid faces laterally instead of posteroventrally. The arm is well muscled and can be interpreted to have been a pennibrachium, as indicated by ulnar papillae on the ulna. The manus is characterized by a short first metacarpal but an elongate phalanx I-1 and oviraptorid-like phalangeal proportions in the second digit. These and other features indicate that the specimen represents a new taxon, Apatoraptor pennatus, gen. et sp. nov. Phylogenetic analysis resolves the complicated relationships of Caenagnathidae and allows the evolution of display features to be traced throughout Oviraptorosauria.

New Findings in the Study of Feathered Dinosaurs and Pterosaurs

New Findings in the Study of Feathered Dinosaurs and Pterosaurs

Authors:

???

Abstract:

An oviraptorid dinosaur Huanansaurus ganzhouensis, belonging to the derived oviraptorid dinosaur, was discovered from the Late Cretaceous deposits in Ganzhou, Jiangxi Province. Its unique skull characteristics provide a new insight into the craniofacial evolution of oviraptorosaurid dinosaurs, paleogeographical distribution and paleoecological environments. Zhenyuanlong suni from the Early Cretaceous Yixian Formation of western part of Liaoning Province is a large, short-armed, winged dromaeosaurid dinosaur. It provides the evidence of feather morphologies and distribution in a short-armed dromaeosaurid dinosaur. The discovery of Zhenyuanlong also provides important evidence for the study of the diversity, the origin of feathers and the flight of Liaoning dromaeosaurid dinosaurs. Orientognathus chaoyngensis is the first Late Jurassic pterosaur discovered in western Liaoning and it is the largest rhamphorhynchinae pterosaur. The discovery of Orientognathus not only fills the temporal gap between the Middle Jurassic and Early Cretaceous pterosaur faunas of China but also plays an important role in the understanding of radiation evolution of rhamphorhynchids from the Late Jurassic. The above-mentioned important discoveries play a key role in our understanding of the hot and difficult issues such as the evolution of oviraptorid dinosaurs, the feather evolution in dromaeosaurid dinosaurs and the origin of bird feathers. In particular, the Ganzhou Dinosaurian Fauna is named based on the discovery of Huanansaurus.

Studying the Bones of a Pregnant Tyrannosaurus

A pregnant Tyrannosaurus rex that roamed Montana 68 million years ago may be the key to discerning gender differences between theropod, or meat-eating dinosaur, species. Researchers from North Carolina State University and the North Carolina Museum of Natural Sciences have confirmed the presence of medullary bone - a gender-specific reproductive tissue - in a fossilized T. rex femur. Beyond giving paleontologists a definitively female fossil to study, their findings could shed light on the evolution of egg laying in modern birds.

Medullary bone is only found in female birds, and then only during the period before or during egg laying. It is chemically distinct from other bone types, like the dense cortical bone that makes up the outer portion of our bones, or the spongy cancellous bone found inside them. This is because medullary bone has to be laid down and mobilized quickly in order for birds to shell their eggs. Theropod dinosaurs, the broader dinosaurian group that includes modern birds and other toothy relatives such as T. rex, also laid eggs in order to reproduce, and paleontologists have hypothesized that they may have had medullary bone as well.

In 2005, Mary Schweitzer, an NC State paleontologist with a joint appointment at the NC Museum of Natural Sciences and lead author of a paper describing the research, found what she believed to be medullary bone in the femur of a 68 million year old T. rex fossil (MOR 1125).

"All the evidence we had at the time pointed to this tissue being medullary bone," Schweitzer says, "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."

Medullary bone contains keratan sulfate, a substance not present in other bone types, but it was previously thought that none of the original chemistry of dinosaur bone would survive millions of years. However, Schweitzer and her colleagues conducted a number of different tests on the T. rex sample, including testing for keratan sulfate using monoclonal antibodies, and compared their results to the same tests performed on known medullary tissue from ostrich and chicken bone. Their findings confirmed that the tissue from the T. rex was medullary bone.

"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," Schweitzer says, although she adds that the fleeting nature of medullary bone means that finding more of it in the fossil record may be difficult.

The femur of MOR1125 was already broken when Schweitzer got it, and she acknowledges that most paleontologists wouldn't want to cut open or demineralize their fossils in order to search for rare medullary bone. However, co-author Lindsay Zanno, an NC State paleontologist with a joint appointment at the NC Museum of Natural Sciences, showed that CT scans of fossils may help narrow down the search.

link.

paper link.

Timurlengia euotica: a new Horse Sized Tyrannosaur Theropod From Turonian Cretaceous Uzbekistan

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

Authors:

Brusatte et al

Abstract:

Tyrannosaurids—the familiar group of carnivorous dinosaurs including Tyrannosaurus and Albertosaurus—were the apex predators in continental ecosystems in Asia and North America during the latest Cretaceous (ca. 80–66 million years ago). Their colossal sizes and keen senses are considered key to their evolutionary and ecological success, but little is known about how these features developed as tyrannosaurids evolved from smaller basal tyrannosauroids that first appeared in the fossil record in the Middle Jurassic (ca. 170 million years ago). This is largely because of a frustrating 20+ million-year gap in the mid-Cretaceous fossil record, when tyrannosauroids transitioned from small-bodied hunters to gigantic apex predators but from which no diagnostic specimens are known. We describe the first distinct tyrannosauroid species from this gap, based on a highly derived braincase and a variety of other skeletal elements from the Turonian (ca. 90–92 million years ago) of Uzbekistan. This taxon is phylogenetically intermediate between the oldest basal tyrannosauroids and the latest Cretaceous forms. It had yet to develop the giant size and extensive cranial pneumaticity of T. rex and kin but does possess the highly derived brain and inner ear characteristic of the latest Cretaceous species. 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.

 Nat Geo article also.

Another link.

Was Tyrannosaurus an Invasive Species?

Tyrannosaurus rex, king of the dinosaur age, wasn't a North American native as many experts had previously thought, a new study suggests.

Instead, the giant tyrannosaur was likely an invasive species from Asia that dispersed into western North America once the opportunity presented itself, paleontologists said.

"It's possible that T. rex was an immigrant species from Asia," said study co-researcher Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland. But he cautioned that the finding isn't necessarily a "slam dunk," and that more research is needed to say for sure.

link.