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18 04, 2019

Early Miocene Giant Hyaenodont Bigger than a Polar Bear

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Simbakubwa kutokaafrika – Giant African Hyaenodont

Scientists writing in the “Journal of Vertebrate Paleontology” have described a new species of giant Hyaenodont from sub-Saharan Africa that was bigger than a polar bear.  The giant carnivore, most likely the apex predator in its Early Miocene ecosystem, has been named Simbakubwa kutokaafrika and this fearsome beast with its huge teeth is the stuff of nightmares.

A Life Reconstruction of the Newly Described Giant Hyaenodont Simbakubwa kutokaafrika

Simbakubwa kutokaafrika life reconstruction.

A life reconstruction of the newly described giant hyaenodont Simbakubwa kutokaafrika.

Picture Credit: Mauricio Anton

A Chance Discovery

Co-author of the scientific paper Matthew Borths (Duke University, North Carolina), was visiting the Nairobi National Museum in Kenya in 2013  to view some specimens.  He asked to view the contents of a collection labelled as “hyaenas” and he discovered a gigantic lower jaw bone more than forty centimetres in length.   The bones and teeth had been placed in a drawer after a dig in western Kenya in the late 1970’s and had remained there ever since.

The genus name, Simbakubwa is from Swahili “simba” meaning “lion” and “kubwa” meaning “big”, big this animal certainly was, its body weight has been estimated at over 1,500 kilograms making S. kutokaafrika heavier than the largest land carnivore alive today, the polar bear (Ursus maritimus).  The species name kutokaafrika, is also from Swahili, it means “from Africa”.

The Lower Jaw of S. kutokaafrika Compared to the Jaw of a Modern Lion (Panthero leo)

Simbakubwa jaw compared to the jaw of a lion.

Simbakubwa kutokaafrika mandible, with Panthera leo mandible for comparison.

Picture Credit: Journal of Vertebrate Paleontology

The picture (above), shows the holotype left dentary (KNM-ME 20A), in (A) lingual, (B) buccal and (C) occlusal views.  It is compared in size to the lower jaw of a modern lion (Panthero leo), photograph (D).  Note the scale bar is 5 cm.

Classified as a Member of the Hyaenodonta (Hyainailourinae)

The carnivore has been classified as a member of the Hyaenodonta (Hyainailourinae), a large and diverse group of creodonts that may have evolved in Africa.  These animals dominated predatory niches in ecosystems until the emergence of the modern Carnivora.  As such, Simbakubwa is only very distantly related to today’s big cats the Felidae.

The Giant Teeth of a Giant Prehistoric Predator

Views of the teeth of Simbakubwa kutoaafrika.

What big teeth you have – Simbakubwa kutokaafrika.

Picture Credit: Journal of Vertebrate Palaeontology

The photograph (above), shows isolated teeth associated with the lower jaw.  Pictures (A, B and C) show a right lower canine in lingual, buccal and occlusal views.  A right molar (m1), is shown in (D) occlusal, (E) lingual and (F) buccal views and the second right molar (m2), is shown in (G) occlusal, (H) lingual and (I) buccal views, whilst a left molar (m2), is show in (J) occlusal, (K) lingual and (L) buccal views.  Note the scale bar equals 5 cm.

A Widely Dispersed Clade of Super-sized Mammalian Predators

The hyainailourine hyaenodonts are among the biggest land mammalian carnivores known to science.  The group is temporally and geographically widely dispersed with fossil finds in Europe, Asia, North America, Arabia as well as Africa.  The fossil material assigned to the Simbakubwa genus represent the most complete hyainailourine known from sub-Saharan Africa.  The researchers conclude that the fossils represent a relatively young adult animal and the material was collected at the Meswa Bridge site (western Kenya).

Bayesian ancestral state reconstruction supports an Afro-Arabian origin for Hyainailourinae with subsequent dispersal to Europe and Asia.  A regression analysis conducted by the authors of the paper, based on carnassial size suggests that Simbakubwa could have weighed around 1,500 kilogrammes, more than four times the weight of a modern African lion.   The evolution and extinction of Hyainailourinae offers important insights for interpreting ecological transitions from Paleogene to Neogene faunas in Afro-Arabia and Eurasia.

The scientific paper: “Simbakubwa kutokaafrika, gen. et sp. nov. (Hyainailourinae, Hyaenodonta, ‘Creodonta,’ Mammalia), a gigantic carnivore from the earliest Miocene of Kenya” by Matthew R. Borths and Nancy J. Stevens published in the Journal of Vertebrate Paleontology.

15 04, 2019

Scientists Identify Ancient “Monster” from the Deep

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Tentacled “Cthulhu” Fossil Reveals Relative of Modern Sea Cucumbers

The remarkable Silurian-aged deposits located at a secret site in Herefordshire (England), have provided scientists with a unique look at the early evolution of sea cucumbers and their relatives.  The rocks at this location are comprised of very fine grained volcanic ash that settled on the seafloor some 430 to 425 million years ago.  These deposits have preserved in fantastic detail the remains of the marine biota.  The latest new species to be named from this location is Sollasina cthulhu, a multi-tentacled, benthic animal that was a ferocious predator.  The prehistoric sea cucumber’s trivial name honours the “Cthulhu” universe, as it resembles some of the monsters created by the American, 20th Century science-fiction writer H. P. Lovecraft.  At only three centimetres across, it might not look very formidable to us, but its numerous tentacles, (actually tube feet), would have been used to terrorise and capture other animals as it roamed across the seafloor.

A Life Reconstruction of the Newly Described Sollasina cthulhu

Life reconstruction of the Silurian ancestral sea cucumber Sollasina cthulhu.

Sollasina cthulhu life reconstruction.

Picture Credit: Elissa Martin, (Yale Peabody Museum of Natural History)

Writing in the academic journal the “Proceedings of the Royal Society B (Biology)”, palaeontologists from the USA and the UK were able to create an accurate, three-dimensional digital reconstruction of the 430 million-year-old fossil.  The exceptionally preserved fossil, once analysed using this three-dimensional computer modelling technique, revealed details of internal soft tissues previously not seen in a fossil like this.

Sollasina cthulhu

Like other fossils from the secret Herefordshire “Lagerstätte”, Sollasina cthulhu was examined using a method that involved grinding it away, layer-by-layer, with a photograph taken at each stage.  This led to hundreds of images being produced which were then combined in a special computer programme to create an exact 3-D image, a “virtual fossil”.  The scientists, which included researchers from the Oxford Museum of Natural History, Leicester University, Imperial College London, Yale University and the University of Southern California, were able to make out an internal ring, which is believed to be part of the organism’s water vascular system.  The water vascular system is the system of fluid-filled canals used for feeding and movement in living sea cucumbers and their relatives.

Dr Imran Rahman (Deputy Head of Research at Oxford University Museum of Natural History) and lead author of the paper stated:

“Sollasina belongs to an extinct group called the ophiocistioids, and this new material provides the first information on the group’s internal structures.  This includes an inner ring-like form that has never been described in the group before.  We interpret this as the first evidence of the soft parts of the water vascular system in ophiocistioids.”

Computer-based Analysis

This new fossil was subjected to a phylogenetic analysis to assess the evolutionary relationships between fossil sea cucumbers and sea urchins (members of the Echinodermata Phylum).  The results showed that Sollasina and its relatives are more closely related to sea cucumbers than they are to sea urchins.  This has provided a new insight into the evolution of this very important group of invertebrates.

A Computer-generated Three-dimensional Image of Sollasina cthulhu

3-D computer generated image of S. cthulhu (tube feet shown in different colours).

Three-dimensional reconstruction of Sollasina cthulhu using the computer programme.  Tube feet shown in different colours.

Picture Credit: Dr Imran Rahman (Oxford University Museum of Natural History)

Dr Jeffrey Thompson (University of Southern California) and a co-author of the paper commented:

“We carried out a number of analyses to work out whether Sollasina was more closely related to sea cucumbers or sea urchins.  To our surprise, the results suggest it was an
ancient sea cucumber.  This helps us understand the changes that occurred during the early evolution of the group, which ultimately gave rise to the slug-like forms we see today.”

The Herefordshire site has provided palaeontologists with some remarkable fossils to study:

An ancient Silurian ostracod: An Ancient Ostracod from Herefordshire

A rare Silurian marine worm: Rare Silurian Fossil Worm from a Herefordshire “Hotspot”

A Prehistoric Scene – Life in the Silurian Seas

Life in the Silurian seas.

A typical Silurian marine biota.  The ecosystem is dominated by arthropods, corals, brachiopods and molluscs.

Picture Credit: The Open University

Everything Dinosaur acknowledges the assistance of a press release from the Oxford University Museum of Natural History in the compilation of this article.

The scientific paper: “A New Ophiocistioid with Soft-tissue Preservation from the Silurian Herefordshire Lagerstätte, and the Evolution of the Holothurian Body Plan” by Imran A. Rahman, Jeffrey R. Thompson, Derek E. G. Briggs, David J. Siveter, Derek J. Siveter and Mark D. Sutton published in the Proceedings of the Royal Society B.

12 04, 2019

A New Species of Therizinosaur from China

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Lingyuanosaurus sihedangensis – A New Species of Therizinosaur is Announced

Scientists from the Chinese Academy of Sciences in collaboration with the University of Alberta, have announced the discovery of a new Therizinosaur based on fragmentary fossils from the Lower Cretaceous Jehol Group of Liaoning Province (north-eastern China).   This is the third Therizinosaur to have been named from the Jehol Group, joining Jianchangosaurus and Beipiaosaurus.  These dinosaurs are approximately the same size, the researchers have put forward a number of theories to help explain why three similar-sized members of the Therizinosauridae could have potentially co-existed without directly competing.

The dinosaur has been named Lingyuanosaurus sihedangensis (pronounced: ling-you-an-oh-sore-us), the genus name honours the city of Lingyuan, whilst the trivial epithet refers to the town of Sihedang where the fossils were discovered.

Fossil Material Ascribed to Lingyuanosaurus sihedangensis Prior to Complete Preparation

Lingyuanosaurus fossils.

Lingyuanosaurus fossil material.

Picture Credit: Scientific Reports

The picture above shows some of the fossils used to name and describe this new species of dinosaur.  Top left (a), limb bones consisting of a right femur and left tibia, whereas, (b) contains ribs, part of the right humerus and the ischium.  Slab (c) consists of claw bones (manual unguals) and ribs, whilst (d), shows the right ankle bone (astragalus) and the left ilium.  Note the scale bar equals 5 cm.

An Intermediate Position within the Therizinosauria

Described from a single, disarticulated but associated partial skeleton, the exact age of the fossils is disputed.  The fossil-bearing strata at Sihedang have been assigned to the Yixian Formation in some studies but to the younger Jiufotang Formation in others.  A phylogenetic analysis carried out by the authors places Lingyuanosaurus in an intermediate position within Therizinosauria.  It has been placed between the early-branching Therizinosaurs such as Falcarius, Jianchangosaurus, and Beipiaosaurus and the late-branching ones such as Alxasaurus and Therizinosaurus.  Lingyuanosaurus sheds additional light on the evolution of major Therizinosaurian characteristics, including the distinctive pelvic girdle and hindlimb morphology seen in this group.

A Drawing of a Typical Therizinosaur

Drawing of a typical Therizinosaurus.

A drawing of a typical Therizinosaur.

Picture Credit: Everything Dinosaur

Where Did Lingyuanosaurus Fit into the Jehol Biota?

Measuring around two metres in length, this is the third similar-sized Therizinosaur to be assigned to this Early Cretaceous biota of northern China.  The presence of three very similar types of dinosaur in the Jehol Group is unusual.  Unless the region was particularly rich in resources, these dinosaurs could have been in direct competition with each other.  The researchers put forward several possible explanations as to why three similar Therizinosaurs have been identified.

  • Firstly, the beds in which these Therizinosaurs (Jianchangosaurus, Lingyuanosaurus and Beipiaosaurus), have been found are not precisely dated.  The Yixian and the Jiufotang Formations were deposited over a span of at least 8 million years.  It is possibly that these three dinosaurs could have been separated from each other by a considerable period of time, hundreds of thousands or even millions of years.
  • Secondly, these three species are known from different parts of Liaoning Province.  Whereas, Jianchangosaurus and Lingyuanosaurus were found at sites just a few miles apart, Beipiaosaurus heralds from more than 200 miles further north.   There is some, albeit limited, evidence to suggest that during the Early Cretaceous the deposition of the Jehol Group occurred in multiple small basins, suggesting that the three Jehol Therizinosaurs might have been separated by geographic barriers even if they were mutually contemporaneous.
  • Thirdly, if these three Therizinosaurs did live at the same time, in the same habitat, they might have occupied different niches in the ecosystem.  The teeth of Jianchangosaurus are different (although the holotype represents a juvenile, so comparison with fully grown animals can be problematic), this suggests that Jianchangosaurus might have fed on different types of vegetation compared to Lingyuanosaurus and Beipiaosaurus.  In addition, the ratio of limb bones in Beipiaosaurus is different to the other two dinosaurs, it might have been relatively slow in comparison with Jianchangosaurus and Lingyuanosaurus and therefore it could have had a more limited range.

Claw Fossils (Manual Unguals) – Lingyuanosaurus sihedangensis

Manual unguals (Lingyuanosaurus).

Claw fossils of Lingyuanosaurus (manual unguals).

Picture Credit: Scientific Reports

The scientific paper: “A New Transitional Therizinosaurian Theropod from the Early Cretaceous Jehol Biota of China” by Xi Yao, Chun-Chi Liao, Corwin Sullivan and Xing Xu published in Scientific Reports

11 04, 2019

A New Species of Early Human from the Philippines

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Another Branch on the Hominin Family Tree – Homo luzonensis

Over the last thirty years or so, our understanding of the evolution of the human family tree has moved on considerably.  Ironically, it is not so much the discovery of new fossils that have helped to fill in the significant gaps in our knowledge, although recent discoveries, most notably in South Africa have helped to improve our understanding.  Advances in our understanding of the genome of our own and closely related species such as the Neanderthal can perhaps be cited as having the greatest impact.  However, our family tree is far from understood and a new paper, published in the journal “Nature” this week, only demonstrates how much more we have to learn.  Indeed, the human family tree has another branch, step forward Homo luzonensis from Luzon Island in the Philippines.  This hominin may have been small in stature, but this is big news for anthropologists.

One of the Co-authors of the Scientific Paper (Professor Philip Piper) Holding a Cast of a Toe Bone

A cast of the toe bone of Homo luzonensis.

Professor Piper (Australian National University), holding a cast of a toe bone assigned to H. luzonensis.

Picture Credit: Lannon Harley (Australian National University)

The picture (above) shows Professor Philip Piper (School of Archaeology and Anthropology, Australian National University), holding the cast of a hominin third metatarsal (toe bone).  The fossil was found in 2007 in the Callao Cave system (northern Luzon, Philippines) and dated to 67,000 years ago.  Ascribed to the genus Homo, it provided the earliest direct evidence of a human presence in the Philippines archipelago, but to which species did this toe bone belong?

A New Species of Human

Researchers from the National Museum of Natural History (Paris), Bordeaux University and the University of Poitiers, along with colleagues from the Griffith University and the Australian National University were led by Dr Armand Mijares (University of the Philippines).  During the excavations at the Callao Cave site, a total of thirteen fossil specimens were found relating to humans, teeth, foot, finger and hand bones as well as a partial femur.  The scientists have concluded that the material represents at least three individuals.

The finger and toe bones are curved, suggesting that climbing was still an important activity for this human species.

Curved Toe and Finger Bones Indicate that Tree Climbing was Important for Homo luzonensis

The curved pedal (toe bone) of H. luzonensis.

Homo luzonensis fossil digits and toes indicate that tree climbing was very important to this human species.

Picture Credit: Florent Détroit (Natural History Museum, Paris)

Commenting on the importance of these fossils, Professor Piper stated that this discovery represents a major breakthrough in our understanding of human evolution across south-eastern Asia.

A Relatively Small Hominin

Professor Piper explained:

“The size of the teeth generally, though not always, reflect the overall body-size of a mammal.  So, we think Homo luzonensis was probably relatively small.  Exactly how small we don’t know yet.  We would need to find some skeletal elements from which we could measure body-size more precisely.”

The researchers conclude that the hands and feet are reminiscent of the hands and feet of Australopithecines.  The Australopithecines are considered to be the ancestors of the Homo genus, which includes our own species – H. sapiens.

Posing Difficult Questions

The latest branch to the human family tree is posing a number of intriguing questions to palaeoanthropologists.  Did these primitive anatomical features result in this species of hominin due to adapting to an island life, after all Luzon was heavily forested, or are these traits resulting from primitive African hominins migrating to south-east Asia?

Summarising the situation, Professor Piper stated:

“So, the question is whether some of these features evolved as adaptations to island life, or whether they are anatomical traits passed down to Homo luzonensis from their ancestors over the preceding two million years.”

The Callao Cave System Has Been the Focus of a Number of Archaeological Excavations

The Callao Cave complex (Luzon Island).

Excavations at the Callao Cave complex.

Picture Credit: Callao Cave Archaeology Project

The Origins of Homo luzonensis

Recent excavations near the Callao Cave complex have produced evidence of a butchered rhinoceros and many types of stone stool, some of which have been dated to around 700,000 years ago.

Professor Piper said:

“No hominin fossils were recovered, but this does provide a timeframe for a hominin presence on Luzon.  Whether it was H. luzonensis butchering and eating the rhinoceros remains to be seen.”

Fossil Teeth of Homo luzonensis

Homo luzonensis teeth.

The teeth are quite small and helped to support the erection of a new species.

Picture Credit: Florent Détroit (Natural History Museum, Paris)

The Significance of South-East Asia

The identification of a new species of human in the Philippines makes the whole of south-east Asia very significant.  The Philippines is made up of many thousands of islands, it is possible that other islands may have had hominin populations that could be described as a new species, indeed, within the archipelago there could be evidence for several species of hominin.  For example, stone tools dating to around 200,000 years ago have been found on the Indonesian island of Sulawesi.   This suggests that ancient members of the human family tree may have inhabited many of the larger islands in south-east Asia.

Homo floresiensis and the Denisovans

Scientists are aware that south-eastern Asia was home to another species of human, the enigmatic Denisovans, which are known from just a handful of fossil bones found in the mountains of Siberia, but DNA studies have revealed that the Denisovans interbred with early modern humans in this region.  No fossil remains relating to the Denisovans have been found in south-eastern Asia thus far.

In addition, the Indonesian island of Flores was home to a hominin species (Homo floresiensis).  These diminutive people, nicknamed Hobbits because the scientific paper was published at the height of the interest in the “Lord of the Rings” film trilogy, are thought to have lived as recently as 50,000 years ago.

An article on Homo floresiensisDid Modern Humans Drive the Hobbit (H. floresiensis) to extinction?

Intriguingly, anthropologists have argued that H. floresiensis exhibits physical features that are reminiscent of those found in Australopithecines.   However, other researchers have argued that the Hobbits were descended from Homo erectus but that some of their anatomy reverted to a more primitive state, perhaps as a result of living on an island with limited resources.

For an article that discusses the significance of south-east Asia in human evolution: Did Humans Evolve Independently in Asia?

7 04, 2019

The First Alaskan Lambeosaurine Dinosaur Identified

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Lambeosaurine Reported from the Liscomb Bonebed (Alaska)

The first fossil evidence of a lambeosaurine duck-billed dinosaur has been reported from the Liscomb Bonebed (Prince Creek Formation) of Alaska.  Part of the top of a skull, a bone called the supraoccipital (it forms part of the braincase), has been found during field work on the famous Alaskan fossil site on the banks of the Colville River.  This discovery demonstrates that both lambeosaurine and hadrosaurine dinosaurs lived in the high Arctic during the Late Cretaceous.  It also suggests that the crested lambeosaurines may have preferred inland environments, whilst their cousins, the hadrosaurines dominated the ecosystem in coastal and low-lying, near shore environments.

Evidence to Indicate that Lambeosaurines Lived in the Arctic During the Late Cretaceous

Co-existing lambeosaurines and hadrosaurines (Liscomb Bonebed).

Hadrosaurines and lambeosaurines co-existed in low-lying, coastal areas of the Late Cretaceous of Alaska.

Picture Credit: Masato Hattori

Writing in the on-line, academic journal “Scientific Reports”, researchers from Hokkaido University (Japan) and the Perot Museum of Nature and Science (Dallas, Texas), confirm the discovery of a skull bone associated with a lambeosaurine (crested duck-billed dinosaur) in the hadrosaurine dominated Liscomb Bonebed, a site that has to date, yielded some 6,000 dinosaur bones.  The fossils exposed on the banks of the Colville River in a region of Alaska known as the North Slope, represent one of the most important Maastrichtian-aged dinosaur fossil sites in the world.  It has provided evidence of a high latitude Late Cretaceous dinosaur dominated ecosystem.  The bonebed is described as a monodominant, multitaxic unit as although 98.5% of all the fossils found represent just one species – the hadrosaurine Edmontosaurus* other types of dinosaur including three Theropods have been identified from fossils found at this site too.  The supraoccipital confirms the presence of lambeosaurines at this location as well, although, based on the ratio of hadrosaurine to lambeosaurine fossils found, crested duck-billed dinosaurs probably only made up a tiny portion of the entire plant-eating dinosaur community.

Views of the Single Skull Bone (Supraoccipital) Identified as Lambeosaurine

Lambeosaurine supraoccipital (DMNH 2014-12-266) from the Liscomb Bonebed.

Lambeosaurine supraoccipital (DMNH 2014-12-266) from the Liscomb Bonebed (a) dorsal view, (b) ventral view, (c) left lateral view, (d) posterior view, (e) anterior view and (f) right lateral view.  Note scale bar = 2 cm.  The dorsal (a) and posterior views (d) show the two, prominent bumps (squamosal bosses) that helps to identify this bone as lambeosaurine material.  Abbreviation sqb = squamosal bosses.

Picture Credit: Scientific Reports

The newly described supraoccipital differs from those of hadrosaurines as it has large, prominent bumps towards the back of the bone (squamosal bosses).  It is also a different shape when compared to supraoccipital bones associated with members of the Hadrosaurinae such as Edmontosaurus.  For example, it is proportionally shorter in length (when measured from the front to the back of the bone – anterior to posterior).

Lambeosaurine and Hadrosaurine

The dinosaur family known as the Hadrosauridae is split into two main, but closely related lineages, the Lambeosaurinae and the Hadrosaurinae.  Traditionally, these two groups have been distinguished by their skulls, lambeosaurines having hollow crested skull crests, whilst the hadrosaurines lack bony crests.  This assessment might prove too simplistic, but for the time being, the general classification of Hadrosaurs into these two sister lineages remains the consensus.

Classifying the Hadrosauridae (Duck-billed Dinosaurs)

The evolution of the duck-billed dinosaurs.

Tracing the Evolution of Duck-billed Dinosaurs.  Two distinct but sister lineages are recognised the non-crested Hadrosaurinae and the hollow crested Lambeosaurinae.

Picture Credit: Everything Dinosaur

Co-author of the scientific paper, Dr Anthony Fiorillo (Perot Museum of Nature and Science) stated:

“This first definitive evidence of a crested hadrosaur in the Cretaceous Arctic tells us that we still have much to learn about the biodiversity and the biologically productive environments of the ancient north and that the story these fossils tell us is continually evolving.”

Field Team Members Excavating Part of the Liscomb Bonebed on the Banks of the Colville River (Alaska)

Excavating the Liscomb Bonebed.

Field team members excavating the Liscomb Bonebed.

Picture Credit: Dr Anthony Fiorillo (Perot Museum of Nature and Science)

A Link Between the Lambeosaurines of North America and Asia

The single fossil bone might not be sufficient to erect a new genus of lambeosaurine dinosaur, but the discovery is extremely significant as it links the dinosaur biota of the most northerly portions of North America to dinosaur faunas from the Late Cretaceous of northern Asia.  For example, Nipponosaurus (N. sachalinensis) from the North Pacific island of Sakhalin, is also a lambeosaurine.

Commenting on the connection between Arctic dinosaur faunas and those of the North Pacific, co-author Ryuji Takasaki (Hokkaido University) said:

“This new discovery illustrates the geographic link between lambeosaurines of North America and the Far East.  Hopefully, further work in Alaska will reveal how closely the dinosaurs of Asia and North America are connected.”

Known Geographical Distribution of Lambeosaurine Dinosaurs in the Late Cretaceous

The known distribution of lambeosaurines during the Late Cretaceous

Palaeogeographical records of lambeosaurines during the Late Cretaceous.  The red star represents the Liscomb lambeosaurine fossil find.

Picture Credit: Scientific Reports

Hadrosaurines and Lambeosaurines Had Different Habitat Preferences

The Liscomb Bonebed might be dominated by fossil material assigned to the Hadrosaurinae, but the discovery of a single fossil bone indicates the presence of lambeosaurines.  This site is representative of a coastal, near-shore environment and it differs from the lambeosaurine dominant structures of localities in Russia and China interpreted as inland environments.  The researchers postulate that crested duck-billed dinosaurs (lambeosaurines), preferred inland habitats, whilst the non-crested duck-bills (hadrosaurines), favoured coastal habitats.   Different habitat preferences might have been a strategy to avoid excessive competition between these two groups of closely related dinosaurs.

Lambeosaurine and Hadrosaurine Habitats (Inferred from the Liscomb Bonebed)

Differential habitat preference between hadrosaurines and lambeosaurines.

Hadrosaurines (grey) may have preferred lowland coastal habitats whilst the lambeosaurines (black) may have dominated faunal ecosystems further inland.

Picture Credit: Scientific Reports

Note: Edmontosaurus*

Things are never that straight forward in vertebrate palaeontology.  In 2015, a new taxon of hadrosaurine was erected based on the Liscomb duck-billed dinosaur bones.  The new species was named Ugrunaaluk kuukpikensis and although it was believed to be closely related to Edmontosaurus, it was established as a separate taxon.  However, in 2017 subsequent analysis challenged this conclusion.  Ugrunaaluk had been erected based on the study of fossil bones from immature individuals of various growth stages.  The hadrosaurine bones from the Liscomb Bonebed overwhelmingly represent the remains of juveniles.  The establishment of a unique duck-billed dinosaur taxon for northern Alaska remains controversial.  Many palaeontologists now consider Ugrunaaluk to be nomen dubium (not a valid genus).

To read Everything Dinosaur’s 2015 article about Ugrunaaluk kuukpikensisAlaska’s Latest Dinosaur Ugrunaaluk kuukpikensis

The scientific paper: “The First Definite Lambeosaurine Bone From the Liscomb Bonebed of the Upper Cretaceous Prince Creek Formation, Alaska, United States” by Ryuji Takasaki, Anthony R. Fiorillo, Yoshitsugu Kobayashi, Ronald S. Tykoski and Paul J. McCarthy published in Scientific Reports.

5 04, 2019

Four-Legged Whale Ancestor from the Eocene of Peru

By | April 5th, 2019|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Peregocetus pacificus – The Travelling Whale that Reached the Pacific

A team of international researchers including scientists from Peru, France, Belgium, Italy and Holland have announced the discovery of an ancient four-legged whale from Peru.  The fossil discovery suggests that early whales crossed the South Atlantic more than 42.6 million years ago (Lutetian faunal stage of the Eocene).  The fossil material comes from the Playa Media Luna, in Peru’s desert-like Pisco Basin.  It is the oldest fossil of a whale found to date in the New World.

A Life Reconstruction of the Newly Described Early Cetacean – Peregocetus pacificus

Peregocetus pacificus life reconstruction.

Life reconstruction Peregocetus pacificus.  Note: the tail fluke is speculative.

Picture Credit: A Gennari/Royal Belgian Institute of Natural Sciences

In 2011, an international team of palaeontologists excavated a well-preserved skeleton of a four-legged whale ancestor.  Writing in the academic journal, “Current Biology”, the scientists conclude that P. pacificus illustrates a key phase in the evolution and dispersal of early whales.  It represents the first record of an amphibious whale for the whole Pacific Ocean and its discovery supports the hypothesis for an early dispersal of primitive cetaceans to the New World across the South Atlantic.

Field Team Members Working on a Block of Fossil Bones

Peregocetus pacificus fossil excavation.

Field team members working on a block of bones (Peregocetus pacificus).

Picture Credit: Christian de Muizon (Natural History Museum – Paris)

A Quadruped with a Powerful Tail to Assist with Swimming

The first whales are believed to have evolved around fifty million years ago, from terrestrial, hoofed, quadrupeds such as Indohyus from Kashmir.  To read an article about Indohyus: Deer-like Fossil Confuses Whale Evolution.  The discovery of  Peregocetus pacificus will help to fill in some of the gaps in the fossil record of early members of the Cetacea.  Dr Olivier Lambert of the Royal Belgian Institute of Natural Sciences and a co-author of the scientific paper stated:

“This is the most complete specimen ever found for a four-legged whale outside of India and Pakistan.”

A View of a Fossilised Rib of Peregocetus pacificus

Peregocetus pacificus rib bone (in situ).

Peregocetus pacificus rib bone partially excavated at the dig site.

Picture Credit: G. Bianucci (University of Pisa)

The Oldest Four-Legged Whale of the New World

Peregocetus combines terrestrial locomotion abilities and use of the tail for swimming, although the presence of a partial tail fluke as seen in the above illustration is speculative.  Measuring between 3.4 to 4 metres in length, it probably resembled a large otter and like extant otters, it most likely hunted in the water and preyed on fish.  The scientific name translates as “the travelling whale that reached the Pacific Ocean”, a reflection of this being the oldest New World whale fossil discovered to date.  Although, not a complete skeleton, the fossil material represents the most complete skeleton of a four-legged whale outside India and Pakistan.

Olivier Lambert added:

“The animal could carry its own weight and crawl about on land.  We can see this, among other things, because the pelvis is firmly attached to the sacrum and the front and hind legs are very similar to those of Peregocetus’s ancestors from India and Pakistan.  You can even see marks of small hooves on the toes and fingers.”

Line Drawings Illustrating the Known Skeletal Material of Peregocetus in Swimming and Terrestrial Positions

Peregocetus pacificus line drawings (swimming and on land).

Preserved parts of the skeleton showing proposed terrestrial and swimming positions.

Picture Credit: Olivier Lambert (Royal Belgian Institute of Natural Sciences)

The picture (above), shows schematic drawings of the skeleton of Peregocetus in a swimming (top) and a walking stance (bottom), showing the main preserved bones.  Stippled lines indicate reconstructed parts.

Like a Giant Otter

The researchers are confident that Peregocetus was an accomplished swimmer, perfectly at home in the water.  The last few tail bones (caudal vertebrae), have not been found, so it is not possible to state whether this early whale had a tail fluke, but Lambert observed:

“The anatomy of the first vertebrae of the tail resembles that of amphibious mammals such as otters and beavers.  So, we think the animal propelled itself through the water by wave-like movements of the posterior part of the body, including the tail, and by moving its large feet and long toes that were most likely webbed.”

Cranial and Postcranial Material (Peregocetus pacificus)

The lower jaw and postcranial fossil bones of Peregocetus pacificus.

Mandible and postcranial bones of Peregocetus pacificus.

Picture Credit: G. Bianucci (University of Pisa)

A Very Long Journey

The scientists suggest that the ancestors of Peregocetus crossed the Atlantic Ocean between North Africa and the northernmost portion of South America.  During the Eocene, the Atlantic Ocean was only half as wide as it is today and the prevailing surface currents from Africa to South America would have helped the ancestors of Peregocetus to reach the other side.  Once on the eastern coast of South America, the population gradually moved further northwards and populations were eventually established on the western (Peruvian) coast of South America.  Later, relatives of Peregocetus would spread further north, to the east coast of North America.

The Prepared Lower Jaw of P. pacificus

Peregocetus pacificus lower jaw.

The left mandible (lower jaw) of Peregocetus pacificus.

Picture Credit: Olivier Lambert (Royal Belgian Institute of Natural Sciences)

The Pisco Basin in Peru is proving to be hot-spot for whale fossils.  In 2017, the international team with Olivier Lambert found, 200 metres away from the spot where Peregocetus pacificus was excavated, a 36.4 million-year-old descendant of the basilosaurids, identified as the oldest known member of the mysticete group – Mystacodon selenensis.  Basilosaurids were fully aquatic and mainly used their tail fluke to propel themselves.  Their front limbs had evolved into paddles and the rear legs were much reduced and vestigial.

There are two main types of whale alive today.  Firstly, there is the Odontoceti (toothed whales), such as sperm whales, dolphins and porpoises.   Secondly, there is the Mysticeti, the baleen whales such as the blue, humpback and gray whale.

Everything Dinosaur acknowledges the assistance of a press release from the Royal Belgian Institute of Natural Sciences in the compilation of this article.

2 04, 2019

A New Species of Mastodon Hinding in Plain Sight

By | April 2nd, 2019|Dinosaur and Prehistoric Animal News Stories, Main Page, Photos/Pictures of Fossils|0 Comments

Mammut pacificus – A Newly Recognised Species of Mastodon

A new species of the iconic North American Ice Age prehistoric elephant (Mastodon) has been recognised.  Writing in the academic journal PeerJ, scientists including researchers from the Western Science Centre, California State University, the U.S. Geological Survey and the Department of Earth and Environmental Sciences (Vanderbilt University), in collaboration with other institutions have named Mammut pacificus based on Californian fossil material and specimens from southern Idaho.  This is the first new North American Mastodon species to have been reported in fifty years, ironically, this new Ice Age giant was hiding in plain sight for several decades.

The Holotype Skull and Tusks (M. pacificus)

M. pacificus cranial fossil material and tusks (holotype).

Mammut pacificus cranial fossil material.  Cranium in: (A) dorsal, (B) ventral, (C) left lateral, (D) right lateral, (E) posterior, (F) distal end of left tusk (I1), lateral, and (G) right tusk (I1), lateral view.  Scale equals 10 cm.

Picture Credit: PeerJ/Western Science Centre

Diamond Valley Lake Fossil Finds

The Californian fossil material was excavated from the Diamond Valley Lake site in the 1990’s.  A huge reservoir was being constructed and during the building work in Riverside County, more than 700 Mastodon fossil bones, representing over 100 individuals were discovered.  In total, more than 100,000 skeletal fossils were unearthed during the reservoir project, providing palaeontologists with an insight into the Pleistocene fauna of the western United States.  This material, in conjunction with further Mastodon fossil finds from the construction of the Ziegler Reservoir in Snowmass Village (Colorado), have enabled scientists to build up a much bigger dataset of western North American Mastodon fossils.

For an article that outlines the fossil excavation work carried out during the Ziegler Reservoir project: North American Ice Age Fossil Finds

Concluding the Snowmass dig: Fossil Excavations at Snowmass Village Come to an End

With more Mastodon fossils to study, palaeontologists have been able to identify subtle differences in bone and tooth morphology that cannot be put down to individual variation within a species.

An Illustration of a Typical Mastodon (Scale Drawing of M. americanum)

Scale Drawing American Mastodon.

American Mastodon scale drawing – (Mammut americanum).

Picture Credit: Everything Dinosaur

Different from Mammut americanum

In the scientific paper, the scientists note a number of physical differences between their proposed new taxon and Mammut americanumM. pacificus is described as having more vertebrae within the pelvic region (six sacral vertebrae), a lack of any lower tusk in the jaw and a different shaped femur (thigh bone).  The mid-shaft diameter of the femur is proportionately greater in the Californian specimens.  In addition, the molars are smaller and narrower, even when ontogenetic characters are accounted for.

The Holotype Pelvis (M. pacificus)

Holotype pelvis of M. pacificus (dorsal view).

WSC 18743, M. pacificus holotype pelvis.  Pelvis in dorsal view.  Orthographic view of photogrammetric model.  Scale = 10 cm.

Picture Credit: PeerJ/Western Science Centre with additional annotation by Everything Dinosaur

The researchers claim that the cumulative evidence strongly points to the discovery of a new species.  Furthermore, all known Pleistocene Mammut remains from California are consistent with their diagnosis of M. pacificus.  This suggests that M. americanum was not present in California.  The Californian population may have been isolated from the rest of the Mastodon population for thousands of years, giving rise to a new species.

The scientific paper: “Mammut pacificus sp. nov.  A Newly Recognised Species of Mastodon from the Pleistocene of Western North America” by Alton C. Dooley Jr​, Eric Scott, Jeremy Green, Kathleen B. Springer, Brett S. Dooley and Gregory James Smith published in PeerJ.

1 04, 2019

Amazing Fossils Depict End Cretaceous Mass Extinction Event

By | April 1st, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Geology, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Fossil Discovery Offers Detailed View Minutes After Chicxulub Impact

A paper published in the PNAS (Proceedings of the National Academy of Sciences – USA), provides a detailed snapshot of a terrible natural disaster linked to the Chicxulub bolide impact event.  A site (Tanis), in North Dakota’s Upper Cretaceous Hell Creek Formation, records the devastation caused by a massive surge of water which occurred as seismic shockwaves reverberated around the Earth as a result of the huge extra-terrestrial impact in what is now the Gulf of Mexico.

Examining Rock Layers Looking for Evidence

Exploring sediments, looking for fossils.

Identifying the K-T boundary at the margins of  Upper Cretaceous sediments.

Picture Credit: Robert DePalma (University of Kansas)

A team of palaeontologists, including researchers from the University of Kansas, the Black Hills Institute and Manchester University, in collaboration with a number of other academic institutions report on what has been described as a “motherlode of exquisitely-preserved plant, animal and fish fossils”, the remains of a river ecosystem which flowed into the Western Interior Seaway, which was wrecked within minutes of the extra-terrestrial impact event.

The site is described as a “rapidly emplaced high-energy onshore surge deposit” along the KT boundary that contains associated ejecta and iridium impactite associated with the End Cretaceous extinction event that resulted in the loss of many groups of terrestrial vertebrates including the pterosaurs and the dinosaurs as well as the extinction of a wide variety of marine organisms.

Lead author of the scientific paper, Robert DePalma (University of Kansas), described the site as:

“A tangle mass of freshwater fish, terrestrial vertebrates, trees, branches, logs, marine ammonites and other marine creatures was all packed into this layer by the inland-directed surge”.

One of the Plaster Jackets from the Site Reveals the Devastation

The Tanis Konservat-Lagerstätte

The Tanis Konservat-Lagerstätte.  Plaster field jacket  (A) with partially prepared (freshwater) Acipenseriform fish next to a fragment from an ammonite shell (inset).

Picture Credit: PNAS

The doctoral student went onto add:

“Timing of the incoming ejecta spherules matched the calculated arrival times of seismic waves from the impact, suggesting that the impact could very well have triggered the surge.”

Devastation Occurred Within Minutes of the Impact

The researchers conclude that the fossil site does not record a tsunami.  Tanis is more than 2,000 miles from the bolide impact site in the Gulf of Mexico, a tsunami would have taken at least seventeen hours to reach North Dakota, but seismic waves and a subsequent water surge would have occurred within minutes of the collision.

DePalma and his colleagues describe the rushing wave that shattered the Tanis site as a “seiche.”

What is a Seiche?

A seiche (pronounced “saysh”), relates to a standing wave in an enclosed or part-enclosed body of water.  This term was first used widely by the Swiss scientist François-Alphonse Forel (1841-1912), who pioneered the study of inland water ecosystems.  It is believed the etymology derives from the Swiss/French dialect meaning “swaying back and forth”, a reference to observations of water level changes in alpine lakes.  This phenomenon can have many causes, but seismic activity is known to lead to water surges.

DePalma explained:

“As the 2011 Tohoku earthquake in Japan showed us, seismic shaking can cause surges far from the epicentre.  In the Tohoku example, surges were triggered nearly 5,000 miles away in Norway just 30 minutes after impact.  So, the KT impact could have caused similar surges in the right-sized bodies of water worldwide, giving the first rapid “bloody nose” to those areas before any other form of aftermath could have reached them.”

According to Kansas University researchers, even before the surge arrived, Acipenseriform fish (sturgeon) found at the site already had inhaled tiny spherules ejected from the Chicxulub impact.

Fish Fossils Show Evidence of Microtektites Embedded in Their Gills

Microtektites from the Chicxulub impact recorded in fossil fish.

Fish Fossils show evidence of microtektites embedded in their gills.

Picture Credit: PNAS

The picture above shows Acipenseriform fish with ejecta clustered in the gill region.  Image (A) an X-ray of a fossil sturgeon head (outlined, pointing left; FAU.DGS.ND.161.115.T).  Magnified image (B) of the X-ray in (A) showing numerous ejecta spherules clustered within the gill region (arrows).  Images C and D are micro-CT images of another fish specimen (paddlefish), with microtektites embedded between the gill rakers in the same fashion.

Co-author David Burnham (Kansas University) stated:

“The fish were buried quickly, but not so quickly they didn’t have time to breathe the ejecta that was raining down to the river.  These fish weren’t bottom feeders, they breathed these in while swimming in the water column.  We’re finding little pieces of ejecta in the gill rakers of these fish, the bony supports for the gills.  We don’t know if some were killed by breathing this ejecta, too.”

One of the co-authors of the paper is Californian geologist Walter Alvarez, who, along with is his father Luis, postulated the theory of an impact event playing a role in the End Cretaceous extinction (1980).  They identified a layer of sediment in the strata marking the Cretaceous/Palaeogene boundary (KPg), that was enriched with the rare Earth element iridium and they concluded that an extra-terrestrial object must have collided with the Earth.

The Approaching Bolide About to Strike Planet Earth

Asteroid strikes the Earth.

An extra-terrestrial impact event.  Moments before the impact event, now scientists have fossil evidence providing data on what happened minutes after the collision.

Picture Credit: Deposit Photos/Paul Paladin

Described as a Lagerstätte of the KT Event

The number and quality of preservation of the fossils at Tanis are such that Burnham dubs it the “lagerstätte” of the KT event.  A lagerstätte, comes from the German “storage place”, it describes a sedimentary deposit that contains a large number of very well preserved fossils.  For example, the Tanis site preserves numerous Acipenseriform fish, which are cartilaginous and not bony and therefore less likely to become fossils.

David Burnham added:

“The sedimentation happened so quickly everything is preserved in three dimensions, they’re not crushed.  It’s like an avalanche that collapses almost like a liquid, then sets like concrete.  They were killed pretty suddenly because of the violence of that water.  We have one fish that hit a tree and was broken in half.”

Indeed, the Tanis location contains many hundreds of articulated ancient fossil fish killed by the Chicxulub impact’s consequences and is remarkable for the biodiversity it reveals alone.

Mapping the Direction of the Surge and Examining the Fish Fossils

Carcasses orientated by flow and mass mortality deposit.

A site map (left) showing the flow of water indicated by the orientation of the material and a mass deposit of fish from the site.

Picture Credit: PNAS

Several New Species

The scientists conclude that there are likely to be several new species of fish named as a result of this discovery.  In addition, some specimens are the best known examples of their genus found to date.  It was quickly realised that the surrounding matrix was deposited by a sudden, violent rush of water, a surge that was directed inland away from the Western Interior Seaway.  Impact debris including shocked minerals and ejecta spherules were found in the sediment and a compact layer of KT boundary clay overlies the deposit.

Tanis provides a post impact “snapshot,” including ejecta accretion and faunal mass death, advancing our understanding of the immediate effects of the Chicxulub impact.

According to Burnham, this site will advance our understanding of the Chicxulub impact significantly, describing Tanis as “smoking-gun evidence” of the aftermath.

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

The scientific paper: “A Seismically Induced Onshore Surge Deposit at the KPg Boundary, North Dakota” by Robert A. DePalma, Jan Smit, David A. Burnham, Klaudia Kuiper, Phillip L. Manning, Anton Oleinik, Peter Larson, Florentin J. Maurrasse, Johan Vellekoop, Mark A. Richards, Loren Gurche, and Walter Alvarez published in the PNAS.

30 03, 2019

Juvenile Tyrannosaurus rex Feeding Traces Identified

By | March 30th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Juvenile Tyrannosaurs Fed on Large Hadrosaurs Too

Scientists have identified tooth marks preserved in the tail bone of a duck-billed dinosaur as having been made by a sub-adult Tyrannosaurus rex.  The researchers conclude that late-stage juvenile and subadult Tyrannosaurs were already feeding on the same types of large-bodied prey as adult animals, despite lacking the bone crushing jaws typical of a fully-grown, mature T. rex.

Writing in the academic journal PeerJ, the researchers Joseph E. Peterson and Karsen N. Daus (University of Wisconsin), suggest that this study helps scientists to better understand the diets of Tyrannosaurs and the ecological role they played as predators in Late Cretaceous ecosystems.  Biostratigraphically, the victim’s fossils relate to sediments were Edmontosaurus fossils are found, so the prey has been tentatively identified as an Edmontosaurus.

Evidence of a Subadult T. rex Feeding on a Hadrosaur (Edmontosaurus)

Punctured caudal vertebra suggests feeding by a sub-adult T. rex

The punctured tail bone indicating feeding by a sub-adult T. rex.

Picture Credit: PeerJ

The picture above shows views of the punctured tail bone (BMR P2007.4.1.) in (A) anterior view, (B) posterior view and (C) ventral view.  Images (D and E) are close-up views of the punctures identified on the bottom portion of the caudal vertebra.

Theropod Feeding Traces

Palaeontologists have identified numerous examples of Theropod dinosaur feeding traces and tooth marks.  Such evidence provides information on predator/prey interactions, feeding behaviours and direct evidence of cannibalism in the Dinosauria.  However, in order to determine the meat-eating dinosaur that fed, causing the marks, it is important that the biostratigraphy is known and the approximate likely growth stage of the animal feeding.  The researchers state that currently, most recorded Theropod feeding traces and bite marks are attributed to fully-grown, adult animals, but in this study, the bite marks were compared to various jaws of different aged T. rex specimens and it was concluded that the best fit for the feeding traces came from the maxilla of a late-stage juvenile T. rex estimated to be around 11-12 years old.  The dimensions and spacings on the caudal vertebra best matched the maxillary teeth of specimen number BMR P2002.4.1, a late-stage juvenile T. rex.

A Computer Generated Image Mapping the Feeding Traces

Juvenile T. rex feeding on the tail bone of a duck-billed dinosaur.

Identifying the bite marks on the tail bone of a Hadrosaur.  The dimensions and spacings on the tail bone best matched the maxillary teeth (upper jaw) of BMR P2002.4.1, a late-stage juvenile Tyrannosaurus rex.

 Picture Credit: PeerJ

Hunting or Scavenging?

While bite marks resulting from active predation cannot easily be distinguished from post-mortem feeding traces, the position of the punctures in the Hadrosaur tail bone suggest that the duck-billed dinosaur was already lying on its side and therefore it can be concluded that the traces come from post-mortem consumption.  The researchers propose that further identification of Tyrannosaur feeding traces coupled with experimental studies of the biomechanics of Tyrannosaur bite forces from younger ontogenetic stages may reveal dynamic dietary trends and ecological roles of Tyrannosaurus rex throughout the animal’s life cycle.

Furthermore, this evidence suggests that late-stage juvenile Tyrannosaurs, at least in part, had a similar diet to the adult animals.

The scientific paper: “Feeding Traces Attributable to Juvenile Tyrannosaurus rex Offer Insight into Ontogenetic Dietary Trends” by Joseph E. Peterson and Karsen N. Daus published in the journal PeerJ.

29 03, 2019

The Biggest T. rex Known to Science – “Scotty”

By | March 29th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

“Scotty” – The World’s Biggest T. rex

A scientific paper on what is regarded by many scientists as the world’s biggest Tyrannosaurus rex has been published.  It is time for the “T. rex” specimen nicknamed “Scotty” to step into the spotlight.  It measures around thirteen metres in length and represents an individual more than thirty years of age, remarkably old for a Tyrannosaur.  Based on the diameter of the leg bones and other measurements, the body weight of this formidable carnivore has been estimated at 8.8 Tonnes.  It has been suggested that this specimen (RSM P2523.8), is a little longer and heavier than “Sue” (BHI2033), which resides in the Evolving Planet exhibit at the Field Museum in Chicago.

The “Scotty” T. rex Exhibit Preparing to Make Its Debut at the Royal Saskatchewan Museum

"Scotty" the Tyrannosaurus rex.

A reconstruction of the skeleton of “Scotty” the T. rex

Picture Credit: Amanda Kelley

Gracile and Robust T. rex Forms

On August 16th, 1991, Robert Gebhardt, a high school teacher by profession but also a keen fossil hunter, was working with Tim Tokaryk (palaeontologist at the Eastend Fossil Research Station).  They were exploring the strata exposed along the Frenchman River Valley in Saskatchewan Province, for Robert this was an opportunity to learn more about field work.  However, within a few hours, Robert had found the base of a heavily worn Tyrannosaur tooth, along with a caudal vertebra, the sort of discoveries that seasoned palaeontologists dream about.  Robert had discovered the oldest individual T. rex specimen.

It was not until June 1994, that the excavation work began on this new T. rex specimen in earnest.  The dig site became a visitor attraction in its own right with several thousand people coming to see how the huge bones representing about sixty-five percent of the skeleton were being excavated.  Unfortunately, the sandstone matrix surrounding the fossil bones and teeth was extremely hard, extracting the fossils from their 66-million-year-old rock tomb has proved to be one of the most challenging large Theropod fossil preparations so far undertaken.  Scientists are aware that there seem to be two main types of Tyrannosaurus rex adult body plan – a robust form and a gracile form.  It is not known what these two different body types represent, one could be male, the other female, however, “Scotty”, so named after a celebratory drink of scotch after the initial fossil discovery, is a very robust Tyrannosaurus rex.

A Silhouette Showing the Fossil Material Associated with RSM P2523.8

The skeleton of "Scotty" the T. rex.

A silhouette outline showing the anatomical position of the known skeletal material of “Scotty”.

Picture Credit: University of Alberta, via Agence France-Presse – Getty Images

Scott Persons, (University of Alberta) and one of the authors of the scientific paper published in The Anatomical Record, explained:

“This is the rex of rexes!”

There is considerable size variability among Tyrannosaurus.  Some individuals were lankier than others and some were more robust.  Scotty exemplifies the robust.  He comes out a bit heftier than other T. rex specimens.

Indeterminate Growth

Multiple measurements (including those of the skull, hip, and limbs) show that this was a robust individual with an estimated body mass exceeding all other known T. rex specimens and representatives of all other gigantic terrestrial theropods.  A histological analysis of the fibula (lower leg bone), indicates that Scotty was a mature, adult animal that was over thirty years of age when it died.  Dinosaurs exhibit indeterminate growth, as opposed to most other extant Tetrapods that have determinate growth.  Simply put, this means that a dinosaur grows rapidly when young (T. rex growth spurts in the teenage years for example), but when fully mature, the animal keeps growing albeit at a much reduced pace.  Therefore, a very old individual such as RSM P2523.8, could be larger than other Tyrannosaurs, such as T. rex “Sue”, which is believed to have been around twenty-years of age when it died.

Persons stated:

“Scotty is the oldest T. rex known.  By which I mean, it would have had the most candles on its last birthday cake.  You can get an idea of how old a dinosaur is by cutting into its bones and studying its grown patterns.  Scotty is all old growth.”

Evidence of Pathology – Signs of a Violent Life

Although the fossil material is not as complete as the Field Museum T. rex, just like Sue, the fossilised bones of Scotty show plenty of pathology (evidence of injury or disease).  This dinosaur may have had a long life, but it was a tough life too.  A number of caudal vertebrae are damaged, it has been suggested that this pathology was caused by a bite from another T. rex.  As with many Theropod specimens ribs show evidence of having been broken and subsequently healed and the jaw shows signs of an infection.

Palaeontologist Scott Persons Stares into the Jaws of “Scotty”

Palaeontologist Scott Persons with the cast of the T. rex "Scotty".

Scott Persons stares into the jaws of “Scotty”.

Picture Credit: University of Alberta,  Amanda Kelley via Agence France-Presse – Getty Images

Intriguingly, the skull exhibits a number of lumps and bumps which suggests that T. rex could have had armoured skin, a feature not seen in other T. rex cranial material.   A cast of the fossils will help to form a new mounted Tyrannosaurus rex display, part of an exhibit that is due to open at the Royal Saskatchewan Museum in May 2019.

Scott Persons added:

“I think there will always be bigger discoveries to be made, but as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science.”

Bigger Specimens Awaiting Discovery

The big, robust bones of this Tyrannosaurus rex probably represent the largest of this species so far described.  To most scientists and academics, which dinosaur was the biggest does not really matter, after all, the mass estimates for Tyrannosaurs vary considerably.  However, the authors of the scientific paper, which include Phil Currie and Gregory Erickson, propose that RSM P2523.8 adds weight to the prior hypothesis that there is a sampling bias throughout the Dinosauria.  “Scotty” with its mature, thick-set bones indicates that many other dinosaur taxa grew to significantly greater sizes than currently recognised.

This means, that there are likely to be even bigger dinosaur specimens awaiting discovery…

For the time being, the Royal Saskatchewan Museum can claim that they are putting on display a cast of the heaviest T. rex known to science, a claim that they can make, at least for now.

The Fossilised Remains of Even Older and Larger Specimens Probably Await Discovery

Death of the dinosaurs.

It is likely that larger individuals will be discovered.

Picture Credit: Mark Garlick/Science Photo Library

The scientific paper: “An Older and Exceptionally Large Adult Specimen of Tyrannosaurus rex” by W. Scott Persons IV, Philip J. Currie, Gregory M. Erickson published in the journal The Anatomical Record.

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