Saltriovenator zanellai – One Tonne Giant and Oldest Ceratosaurian Described to Date

Scientists from Natural History Museum of Milan and the Geological Museum of Bologna (Museu di Storia Naturale di Milano and the Museo Geologico), have published a scientific paper on a new predatory dinosaur from the Lombardy region of northern Italy.  This new species was a giant, weighing around a tonne and measuring approximately 7.5 metres in length. It lived some 25 million years before other known big predatory dinosaurs evolved and examination of the fossilised bones suggest that this dinosaur was still growing when it died.  The dinosaur has been named Saltriovenator zanellai and it is the largest theropod described to date from the Early Jurassic (Sinemurian faunal stage).

A Life Reconstruction of the Newly Described Ceratosaurian Theropod Saltriovenator zanellai

Picture credit: Davide Bonadonna

A Chance Discovery

Saltriovenator was discovered by chance in the summer of 1996 by amateur fossil collector Angelo Zanella, whilst exploring fossil rich limestone layers associated with a marble quarry near the town of Saltrio (Varese Province, Lombardy).  The strata containing the fossilised remains represent marine deposits and explosives used in the quarrying process had broken up the fossil bearing layer into hundreds of pieces.  In total, 132 fossil pieces were excavated from the site, the remains of a single animal.

The bones show feeding traces from fish and borings from marine invertebrates.  The palaeontologists writing in the on-line academic journal “PeerJ” suggest that the carcase was washed out sea and stayed on the seabed for some time, permitting the scavenging to take place.

Fossil Elements Used to Confirm Ceratosaurian Affinity with a Skeletal Drawing

Picture credit: G. Bindellini, C. Dal Sasso and M. Zilioli and M. Auditore

The picture above shows key fossils that helped to classify Saltriovenator as a member of the Ceratosauria clade, it is the oldest ceratosaur described to date.

Key

A, B, C = views of the right humerus.

D = left scapula.

E = right scapular glenoid and coracoid.

F = furcula (wishbone).

G = single tooth from the anterior portion of the lower jaw.

I = partial left humerus, the circular depressions represent borings made by marine invertebrates feeding on the carcase.

J, L, N = views of the right second metacarpal (finger bone).

K, M, O, = views of the right second digit.

P-T = views of the right third digit.

U = distal tarsal IV.

V, X = third right metatarsal views.

W, Y = second right metatarsal views.

Z = reconstructed skeleton of Saltriovenator with identified fossil elements shaded red.

Scale bars: 10 cm in (A)–(E), (I), and (U)–(Y); two cm in (F), and (J)–(T); one cm in (G).

A Skeletal Reconstruction of Saltriovenator zanellai 

Picture credit: M. Auditore

The First Jurassic Dinosaur from Italy

Saltriovenator is the first dinosaur to be described from fossils found in the Italian Alps.  It is the first dinosaur from the Jurassic Period to have been found in Italy and the country’s second theropod, the first being Scipionyx samniticus which lived during the Early Cretaceous and at just over two metres in length, was considerably smaller than S. zanellai.  A study of growth rings found in a cross-sectional analysis of the fossil bones indicates that the dinosaur was around twenty-four years of age when it died.

It was still growing, albeit slowly, so the maximum size of this predator is not known, although at an estimated 7.5 metres long, it was considerably bigger than any other theropod from the Early Jurassic described to date.

CollectA have produced a replica of Saltriovenator.

To view this model range: CollectA Deluxe Prehistoric Life Models.

Saltriovenator zannellai – A Mosaic of Basal and More Advanced Theropod Features

Saltriovenator exhibits a mosaic of features seen in four-fingered theropods and basal tetanuran dinosaurs.  The fossilised finger bones indicate that this dinosaur had a fully functioning four-fingered hand, well-adapted for grasping and coping with struggling prey.  Later ceratosaurs had only three fingers on each hand.  Study of the finger bones will help scientists to understand better the evolutionary relationships between the four-fingered cilophosaurs, ceratosaurs and later types of theropod such as the allosaurs with their atrophied hands.

Views of the Pectoral Girdle and the Right Hand of Saltriovenator zanellai

Picture credit: M. Auditore

Commenting on the importance of this fossil discovery, one of the authors of the scientific paper, Dr Andrea Cau (Museo Geologico), stated:

“The grasping hand of Saltriovenator zanellai fills a key gap in the theropod evolutionary tree: predatory dinosaurs progressively lost the pinkie and ring fingers and acquired the three-fingered hand which is the precursor of the avian wing.”

A spokesperson from Everything Dinosaur commented:

“The evolution of large, powerful predatory dinosaurs at the very beginning of the Jurassic, may have been a factor in the evolution of bigger and bigger herbivorous dinosaurs such as the sauropods.  Think of it as an evolutionary arms race as carnivores got bigger, selection pressure was put on herbivores to become bigger and stronger themselves in order to avoid predation.”

Visit the Everything Dinosaur website: Everything Dinosaur.

Nanjinganthus dendrostyla – Putting Back Flowering Plants by 50 Million Years

When did flowering plants (angiosperms) evolve?  That has been a puzzling question, one that has taxed the minds of leading scientists for more than 200 years.  Genetic studies indicate that the diverse and widespread angiosperms have an ancient lineage, but the fossil record does not support this idea.  Fossils of delicate flowers are very rare and the oldest known, date from the Early Cretaceous.  Time for the fossil record to catch up with the announcement of the discovery of a plant that produced flowers some 174 million years ago, during the late Early Jurassic (Toarcian stage).

Specimens of the Newly Described Early Jurassic Flowering Plant Nanjinganthus dendrostyla

Picture credit: (NIGPAS)

The newly described plant has been named Nanjinganthus dendrostyla and it comes from the South Xiangshan Formation (Nanjing, eastern China), which has been studied extensively since the turn of the century and is famous for its abundant plant fossils, which up until now had consisted of cycads, ferns, ginkgoes and horsetails.  Researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), have been able to identify the earliest known examples of a flowering plant, one that predates most of the angiosperm fossil material by around 50 million years.

Fossils Catching Up with the Molecular Clock

Analysis of the genetic data contained in living plant taxa indicates that plants probably evolved earlier than previously thought.  In a study published in February, researchers from the Chinese Academy of Sciences as well as Bristol University, mapped the genetic make-up of 644 types of plant and concluded, based on molecular dating, flowering plants (angiosperms), probably evolved sometime between the Late Permian and the Late Jurassic.

To read Everything Dinosaur’s article summarising this research: When Did Flowers Evolve?

Lots of Fossil Specimens to Study

The researchers studied a total of 264 specimens representing 198 individual flowers preserved on 34 slabs of stone.  The scientists had the luxury of working on so many examples of the same fossil organism.  They produced numerous high resolution images of the flowers allowing the features of N. dendrostyla to be revealed in great detail.  With so many fossil specimens, the scientists were able to exclude other plant types and confirm that the fossils do indeed represent an angiosperm.

A Life Reconstruction of the Earliest Flowering Plant Described to Date

Picture credit: (NIGPAS)

Commenting on the significance of the study, one of the researchers Wang Xin (NIGPAS), stated:

“The origin of angiosperms has long been an academic headache for many botanists.  Our discovery has moved the botany field forward and will allow a better understanding of angiosperms.”

Identifying a Key Feature of Angiosperms

The scientists were able to identify the presence of fully enclosed ovules in the fossilised flowers.  These are the precursors of seeds before pollination.  The reconstructed flower was found to have a cup-form receptacle and ovarian roof that together enclosed the ovules/seeds.  This botanical feature confirms that Nanjinganthus dendrostyla is definitely an angiosperm.

Numerous Examples of N. dendrostyla Preserved in Siltstone

Picture credit: (NIGPAS)

Fossil Flowers in Jurassic Rocks

Discoveries of angiosperm-like fossils have been reported from Jurassic rocks before.  In January (2018), Everything Dinosaur published an article on the remarkable discovery of fossilised wing scales from butterflies and moths that lived during the Late Triassic.  This discovery challenged the theory of co-evolution between flowering plants and pollinating insects such as members of the Lepidoptera.

To read Everything Dinosaur’s article about this: Ancient Butterflies Flutter By.

The morphological features of Nanjinganthus distinguish it from other specimens and suggest that it is a new angiosperm genus.

The scientists hope to determine whether angiosperms are monophyletic (all flowering plants share a common ancestor).  If this is the case and Nanjinganthus is one of the earliest of all the flowering plants, then these fossils represent a stem group giving rise to all later species.  Angiosperms could also be polyphyletic, (a group descended from more than one common ancestor), meaning Nanjinganthus represents an evolutionary dead end and subsequently, it did not give rise to later types of flowering plant.

Visit the Everything Dinosaur website: Everything Dinosaur.

Volgatitan simbirskiensis – Early Cretaceous Leviathan

A team of palaeontologists from Russia have announced the discovery a new genus of titanosaur from fossil bones found on the western bank of the River Volga close to the village of Slantsevy Rudnik in Ulyanovsk Oblast (western Russia).  The dinosaur has been named Volgatitan simbirskiensis, it is one of a trio of sauropods recently described from Russian deposits, the others being Tengrisaurus starkovi and Sibirotitan astrosacralis, both of these herbivorous, long-necked dinosaurs were named and described in 2017.

Volgatitan simbirskiensis

V. simbirskiensis has been named based on the study of seven tail bones (caudal vertebrae), the first of which were discovered following a rock fall on the Volga River back in 1982.

A Scale Drawing of Volgatitan simbirskiensis Showing the Anatomical Position of the Known Fossil Material

Picture credit: St Petersburg State University

For models and replicas of titanosaurs and other sauropods: Dinosaur and Prehistoric Animal Models.

Tell Tale Tail Bones

Fortunately, for the Sauropoda, vertebrae can be quite diagnostic when it comes to ascribing new genera.  Titanosaurs for example, have distinctive shaped caudal vertebrae, especially towards the base of the tail (proximal end close to the hips).  The proximal tail bones of titanosaurs are procoelous (pronounced pro-see-lus), that is, the front face of the bone is concave and the opposite face, the bit that points in the direction of the tail, is bulbous (convex).

Views of the Holotype Caudal Vertebra of V. simbirskiensis

Picture credit: Alexander Averianov and Vladimir Efimov

The photograph (above) shows the holotype caudal vertebra of Volgatitan simbirskiensis in right lateral (A), anterior (B), left lateral (C), posterior (D), dorsal (E) and ventral (F) views.

Dinosaur Nomenclature

The dinosaur’s genus honours the Volga River, whilst the trivial name is in honour of the old name for the city of Ulyanovsk (Simbirsk), after all, the fossils were found just three miles to the north of the city.  Aleksandr Averianov, one of the authors of a scientific paper describing this new titanosaur, published in the journal “Biological Communications”, explained that the description of dinosaur taxa in recent years has become possible due to the progress in understanding the anatomy and phylogeny of the Dinosauria.  Furthermore, the recent Russian sauropod discoveries have allowed scientists to learn more about how these species of lizard-hipped reptiles had lived and developed.

Based on comparisons with the fossilised bones of more complete titanosaurs, Volgatitan is estimated to have been around 16 metres long.  Fully fused neural arches on the centrum from the most proximal of the caudal vertebrae indicate that the bones came from a fully, mature adult animal.

It had been thought that titanosaurs evolved in the Southern Hemisphere, specifically South America, with some taxa migrating into North America, Asia and Europe later in the Cretaceous.  However, the formal description of Volgatitan coming so soon after the naming of Tengrisaurus from the Early Cretaceous of Transbaikal Region, suggests that Early Cretaceous titanosaurs were more widely distributed.  It is possible to postulate that important stages in the evolution of this group of long-necked dinosaurs may have taken place in eastern Europe and Asia.

For an article published in 2017 about the discovery of a new species of African titanosaur: Shingopana songwensis from south-western Tanzania.

To read about an Australian titanosaur discovery made in 2017: Titanosaur “Judy” from the Outback.

Amazing Armoured Dinosaur Zuul Goes on Display

The ankylosaurid named Zuul (Z. crurivastator), is the centrepiece of a new exhibition that opened this week at the Royal Ontario Museum, (Canada).  The exhibition is entitled “ZUUL: Life of an Armoured Dinosaur” and it tells the tale of how this beautifully-preserved dinosaur fossil was discovered and what it can tell us about life in the Late Cretaceous some 76 million years ago.

Zuul – Destroyer of Shins

Picture credit: Royal Ontario Museum

Commenting on this new addition to the Museum’s galleries, Royal Ontario Museum Director and CEO Josh Basseches stated:

“We are thrilled to be introducing Toronto and the world to an extraordinary new dinosaur.  The acquisition of Zuul represents a significant new addition to our globally renowned collection of dinosaurs and fauna.  With the generous support of presenting sponsor Sinking Ship Entertainment, and our team of renowned palaeontologists and exhibition developers, we look forward to presenting a truly unique exhibition that will inspire and delight visitors of all ages.”

Cutting Edge Technology to Showcase Ancient Armoured Giant

The exhibition uses a combination of engaging video games, digital images and animations along with full-sized murals that recreates northern Montana/southern Alberta during the Campanian faunal stage of the Late Cretaceous.

This is the first time that the fossilised remains of Zuul have been put on display anywhere in the world.  Touchscreens will let visitors rotate 3-D views of Zuul’s original fossil pieces, while life-size touchable bronze models of Zuul’s skull, armour, skin, and tail club will permit visitors to feel what it would have been like to touch the living dinosaur.  An animal named after a monster from the 1984 film “Ghostbusters”, Zuul was named in honour of the horned, demi-god Zuul, the Gatekeeper of Gozer from the movie.

A Replica of the Zuul Fossil Material Being Attacked by a Gorgosaurus

Picture credit: Royal Ontario Museum

Dr David Evans, the exhibition’s lead curator and one of the palaeontologists that formally named and described this ankylosaur, commented:

“In this multi-faceted exhibition, visitors will see the breath-taking Zuul fossil up close and through a treasure trove of incredible fossils found alongside the skeleton, learn more about Zuul’s diverse ancient world.  Zuul: Life of an Armoured Dinosaur will spark curiosity about our distant past and the evolution of life over time.”

To read Everything Dinosaur’s article on the discovery of this remarkably complete (95% of the skeleton has been preserved), armoured dinosaur: Zuul – The Destroyer of Shins.

The Beautiful and Fantastically-well Preserved Skull of Zuul crurivastator will be on Display as Part of the Exhibit

Picture credit: Royal Ontario Museum

Safari Ltd recently introduced a model of this armoured dinosaur.

To view the Safari Ltd range: Wild Safari Prehistoric World Models.

From the Judith River Formation of Montana

Heralding from the famous Judith River Formation, Zuul crurivastator is one of the most complete ankylosaur fossils ever found.  It has a complete skull and tail club as well as preserved skin and other soft tissues that will provide a rare and exciting opportunity for new, cutting-edge scientific research.  Zuul was acquired by the ROM in 2016 through the generous support of the Louise Hawley Stone Charitable Trust.

Everything Dinosaur acknowledges the assistance of a press release from the Royal Ontario Museum in the compilation of this article.

Visit the Everything Dinosaur website: Everything Dinosaur.

Study Finds Four Types of Feather-like Structures in Pterosaur Fossils

Most palaeontologists have accepted that it is likely that pterosaurs (flying reptiles), were covered in a sort of hairy fuzz, technically referred to as pycnofibres, that helped insulate their bodies and keep them warm.  However, an international team of scientists from Hong Kong University, Nanjing University (China), University College Cork, University College Dublin (Ireland), the Foundation for Scientific Advancement, (Arizona, USA), the Chinese Academy of Sciences and Bristol University (UK) have published a scientific paper that describes four kinds of feather-like structures associated with the fossilised remains pterosaurs.

If these structures are feathers, then this suggests that either the Pterosauria evolved feathers as a form of convergent evolution, or, that feathers evolved many millions of years earlier than previously thought – in a common ancestor of the Dinosauria and the Pterosauria.

A Life Reconstruction of the Chinese Anurognathid Pterosaur

Picture credit: Yuan Zhang

Two Anurognathid Pterosaur Specimens Studied

Writing in the academic journal “Nature Ecology and Evolution”, the scientists report how high-resolution microscopy revealed evidence of different kinds of pycnofibres on two pterosaur fossils  (representing anurognathids), from the Daohugou Formation in Inner Mongolia.  Although, when the rocks that make up the Daohugou Formation were deposited has been debated and the relative dating of these sediments in relation to other Chinese Jurassic/Early Cretaceous formations has proved controversial, it is suggested that the pterosaurs, one of which represents a new species, lived approximately 160 million years ago.

Four feather-like structures were identified:

• simple filaments (hairs)
• bundles of filaments
• filaments with a tuft halfway down the shaft
• down feathers

The Scientists Identified Four Types of Feather-like Structures in the Fossils

Picture credit: Yang, Jiang, McNamara et al

An Amazing Pterosaur Discovery

One of the paper’s authors, Dr Maria McNamara (University College Cork), stated that some critics have suggested that there is only one simple hair-like type of pycnofibre, but this study shows different structures that we also see in dinosaurs, in essence real feathers.  Furthermore, the team identified melanosomes that indicate that some flying reptiles may have been coloured a sort of reddish brown.

Dr McNamara explained:

“We focused on areas where the feathers did not overlap and where we could see their structure more clearly.  They even show fine details of pigment granules, which may have given the fluffy feathers a ginger colour.  This discovery has amazing implications for our understanding of the origin of feathers, but also for a major time of revolution of life on land.  When feathers arose, about 250 million years ago, life was recovering from the devastating end-Permian mass extinction.”

The Enigmatic Anurognathidae

Only a handful of anurognathid fossils are known and only a few species have been assigned to this pterosaur family.  Although, the first anurognathids were described from Upper Jurassic deposits of Bavaria (Solnhofen limestone), the best preserved and most complete specimens came from the Daohugou Beds of Inner Mongolia.  Since these types of small, short-faced flying reptiles are known from Europe, South Korea, China and potentially North America, they seem to have been geographically widespread.  Although very rare, the Daohugou Bed fossil specimens have some soft tissue and muscle outline preservation and have provided palaeontologists with a lot of information on pterosaur anatomy.

An Anurognathid Pterosaur from the Daohugou Beds – Jeholopterus ninchengensis 

Picture credit: Chinese Academy of Sciences/Journal of Vertebrate Palaeontology

Re-writing the History of the Evolution of Feathers

Feathers are essentially highly modified scales; this new research could potentially re-write the evolutionary history of feathers.  One of the authors, Professor Mike Benton (Bristol University), explained:

“We ran some evolutionary analyses and they showed clearly that the pterosaur pycnofibres are feathers, just like those seen in modern birds and across various dinosaur groups.  Despite careful searching, we couldn’t find any anatomical evidence that the four pycnofibre types are in any way different from the feathers of birds and dinosaurs.  Therefore, because they are the same, they must share an evolutionary origin, and that was about 250 million years ago, long before the origin of birds.”

Birds have two types of advanced feathers used in flight and for body smoothing, the contour feathers with a hollow quill and barbs down both sides.  These types of feathers are found only in birds and the theropod dinosaurs close to the evolutionary origins of the Aves (birds).  However, the other feather types of modern birds include monofilaments and down feathers, and these are seen much more widely across dinosaurs and pterosaurs.

Growth Suppressed

The armoured dinosaurs and the giant sauropods probably did not have feathers, but they were likely suppressed, meaning they were prevented from growing, at least in the adults, just as hair is suppressed in large-bodied animals today such as cetaceans, hippos and elephants.

High Resolution Microscopy Revealed Different Types of Feather-like Structures

Picture credit: Yang, Jiang, McNamara et al

Professor Benton added:

“This discovery has amazing implications for our understanding of the origin of feathers, but also for a major time of revolution of life on land.  When feathers arose, about 250 million years ago, life was recovering from the devasting end-Permian mass extinction.  Independent evidence shows that land vertebrates, including the ancestors of mammals and dinosaurs, had switched gait from sprawling to upright, had acquired different degrees of warm-bloodedness, and were generally living life at a faster pace.” 

He went on:

“The mammal ancestors by then had hair, so likely the pterosaurs, dinosaurs and relatives had also acquired feathers to help insulate them.  The hunt for feathers in fossils is heating up and finding their functions in such early forms is imperative.  It can rewrite our understanding of a major revolution in life on Earth during the Triassic, and also our understanding of the genomic regulation of feathers, scales, and hairs in the skin.”

Different Kinds of Pycnofibres – Different Functions?

Pterosaurs were the first back-boned animals to evolve powered flight.  However, following their extinction at the end of the Cretaceous, they left no living close relatives, nor indeed any near related analogues for scientists to study.  Whilst the presence of pycnofibres on the bodies of these flying reptiles is quite well accepted by the scientific community, their functions are not fully understood.  If different types of feather-like structures have been identified in two anurognathid pterosaur specimens, it is likely that other types of pterosaur had them too.

These different feather-like structures probably served a variety of functions, perhaps the first “pterosaur fuzz” evolved to provide insulation and then other types evolved perhaps to aid tactile sensing, visual communication and to assist with flight.

The scientific paper: “Pterosaur Integumentary Structures with Complex Feather-like Branching” by Z. Yang, B. Jiang, M. McNamara, S. Kearns, M. Pittman, T. Kaye, P. Orr, X. Xu and M. Benton and published in Nature Ecology and Evolution.

Everything Dinosaur acknowledges the assistance of a press release from Bristol University in the compilation of this article.

Visit the Everything Dinosaur website: Everything Dinosaur.

Crittendenceratops krzyzanowskii – A New Horned Dinosaur from Arizona

Many scientists and observers have described the last two decades as the “Golden Age” of dinosaur discoveries.  Since the turn of the century, there have been some astonishing fossil finds and many new species of dinosaur have been discovered and described.  None more so than with the horned dinosaurs and their relatives (Marginocephalia).

Over the last few years, we have reported on numerous new types of ceratopsian, many of these new horned dinosaurs having been discovered in strata laid down in the United States, for example, Medusaceratops, Aquilops, Kosmoceratops and Utahceratops.  Surprisingly, there had been no new horned dinosaurs named in 2018, that is no longer the case with a scientific paper published describing a new centrosaurine dinosaur from the Late Cretaceous of Arizona – Crittendenceratops krzyzanowskii.

A Life Reconstruction of the Newly Described Ceratopsian Crittendenceratops krzyzanowskii

Picture credit: Sergey Krasovskiy

Only a Few Dinosaurs Named from Arizona

Writing in the New Mexico Museum of Natural History and Science Bulletin, the researchers, Sebastian G. Dalman and Asher Lichtig, both Research Associates at the New Mexico Museum of Natural History and Science, in collaboration with John-Paul Hodnett from the Maryland-National Capital Parks Commission and Spencer G. Lucas (a curator at the New Mexico Museum of Natural History and Science), describe Crittendenceratops and assign it the Centrosaurinae subfamily of horned dinosaurs and specifically to the Nasutoceratopsini tribe.

There have been so many new horned dinosaurs from North America named and described in the last twenty years or so, that this has led to a revision of ceratopsian taxonomy.  For example, the Nasutoceratopsini was erected recently (2016).

To read an article that summarises this revision: Redefining the Horned Dinosaurs.

Despite the wealth of dinosaur fossil material associated with the western United States, Crittendenceratops is one of only a handful of dinosaurs named from Arizona.

A Reconstruction of the Parietosquamosal Frill of C. krzyzanowskii

Picture credit: New Mexico Museum of Natural History and Science

Crittendenceratops krzyzanowskii from the Fort Crittenden Formation

This new herbivore has been described from fragmentary fossil material, including skull elements from the shale member of the Fort Crittenden Formation.  Two individual animals are represented by the fossils.  Crittendenceratops is estimated to have been around 3.5 metres in length and would have weighed about 750 kilograms.  It lived 73 million years ago (Campanian stage of the Cretaceous) and the rocks that yielded the bones were deposited along the margins of a large lake that was present in an area southeast of Tucson, Arizona.

The Nearly Complete Left Squamosal (Skull Bone) of Crittendenceratops

Picture credit: New Mexico Museum of Natural History and Science

Honouring Stan Krzyzanowski

The new species was named by Sebastian G. Dalman, John-Paul Hodnett, Asher Lichtig and Spencer G. Lucas.  The genus name reflects the rock formation where the fossils were found (Fort Crittenden Formation), whereas the trivial name honours the late Stan Krzyzanowski, a Research Associate from the New Mexico Museum of Natural History and Science, who discovered the first bones to be ascribed to this new dinosaur in the Adobe Canyon area eighteen years ago.  Crittendenceratops can be distinguished from other members of the Centrosaurinae subfamily by the unique shape of the bones in its frill.

The scientific paper: “A New Ceratopsid Dinosaur (Centrosaurinae Nasutoceratopsini) from the Fort Crittenden Formation Upper Cretaceous (Campanian) of Arizona” by Spencer G. Lucas, Sebastian Dalman, Asher Lichtig and John-Paul Michael Hodnett published in the New Mexico Museum of Natural History and Science Bulletin.

Everything Dinosaur acknowledges the assistance of a press release from the New Mexico Museum of Natural History and Science in the compilation of this article.

Visit the award-winning Everything Dinosaur website: Everything Dinosaur.