New Study Solves Mystery of Tanystropheus

A newly published scientific paper demonstrates that small specimens of Tanystropheus from the Middle Triassic Lagerstätte of Monte San Giorgio (Italy/Switzerland border), represent a separate species (Tanystropheus longobardicus) and that they co-existed with much larger examples of this genus (Tanystropheus hydroides).  Writing in the academic journal “Current Biology”, the researchers which include Olivier Rieppel (Field Museum in Chicago), postulate that the larger species was an aquatic ambush predator, whilst the smaller species fed on other types of prey.

Sophisticated Computer Models Developed from High Resolution CT Scans Identified the Two Species

Picture credit: Spiekman et al (Current Biology)

Tanystropheus longobardicus Remains but Referencing Smaller Species

Tanystropheus represents one of the most bizarre of all the vertebrates known from the Mesozoic.  It is characterised by an extremely long and inflexible neck that is almost three times the length of its torso.  The palaeobiology of this reptile has remained contentious with a fully aquatic, semi-aquatic and entirely terrestrial lifestyle having been proposed since it was formally described back in 1852 (Hermann von Meyer).

An Illustration of the Bizarre Triassic Archosauromorph Tanystropheus

Picture credit: Everything Dinosaur

The research team used high-resolution CT scans to construct three-dimensional computer generated models of fossil specimens that had been crushed and flattened.  The skulls that were constructed revealed that the larger specimens were anatomically very different from the skulls of the smaller specimens.  The smaller morphotype was known for having different shaped teeth when compared to the teeth of larger specimens from the same strata.  Historically, this had been interpreted as evidence for juveniles of T. longobardicus feeding on different types of prey compared to fully-grown adults.

Lead author of the paper, Stephan Spiekman (University of Zurich), explained:

“The power of CT scanning allows us to see details that are otherwise impossible to observe in fossils.  From a strongly crushed skull we have been able to reconstruct an almost complete 3-D skull, revealing crucial morphological details.”

The computer generated models permitted the team to conclude that two species of Tanystropheus co-existed in the Middle Triassic coastal ecosystem.   The larger species, which grew up to six metres long, has been named Tanystropheus hydroides, whilst the smaller species is retained as T. longobardicus.

A Crushed Skull and Examples of a Three-Dimensional Skull Map

Picture credit: Spiekman et al (Current Biology)

A Marine Predator

The study also revealed strong evidence that Tanystropheus hydroides was a marine predator.  The scans of the skull revealed that the nostrils were on top of the snout, rather like a crocodile’s.   The long, pointed teeth in the anterior portion of the jaw enabled it to grab and hold onto slippery prey, the teeth being described by the scientists as a “fish-trap type dentition”.   Both species were probably confined to coastal environments, the larger of the two species ambushing small fish whilst Tanystropheus longobardicus may have fed on shrimps and other  types of crustacean.  Although adapted to a marine habitat, both species probably had to return to land in order to lay eggs.

The co-occurrence of these two species of very different sizes and tooth morphology provides strong evidence for niche partitioning, highlighting the surprising versatility of the Tanystropheus bauplan and the complexity of Middle Triassic nearshore ecosystems.

Line Drawings Comparing the Skull and Bauplan of the Two Tanystropheus Species

Picture credit: Spiekman et al (Current Biology)

The scientific paper: “Aquatic Habits and Niche Partitioning in the Extraordinarily Long-Necked Triassic Reptile Tanystropheus” by Stephan N.F. Spiekman, James M. Neenan, Nicholas C. Fraser, Vincent Fernandez, Olivier Rieppel, Stefania Nosotti and Torsten M. Scheyer published in Current Biology.

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Bone Cancer (Osteosarcoma) Identified in Dinosaur Fibula

Scientists have identified a rare malignant cancer in the fossilised bone of a horned dinosaur.  Writing in “The Lancet Oncology”, the researchers report on the discovery and diagnosis of an osteosarcoma in the lower leg bone (fibula), of a Centrosaurus (Centrosaurus apertus).  This is the first time that an osteosarcoma has been found in the fossilised bones of a dinosaur.

An Osteosarcoma Identified in the Leg Bone of a Dinosaur (Centrosaurus apertus)

Picture credit: Royal Ontario Museum

What is an Osteosarcoma?

Osteosarcoma is a cancer that produces immature bone.  There are an estimated 3.4 million cases reported in the human population each year.  It mostly occurs in young people, under the age of 25 and there is some evidence to suggest that it is more prevalent in males.  In our species, osteosarcoma is associated with periods of rapid bone growth, to date the cause, genetic alterations, oncogenic events and evolutionary history of osteosarcoma are poorly understood.

The research team included scientists from the Royal Ontario Museum, McMaster University (Ontario) and the Okayama University of Science (Japan), along with numerous other specialists in pathology, molecular medicine, image resonance and oncology.  They subjected the leg bone to high-resolution computed tomography (CT) scans.  Thin sections were than prepared and examined under a microscope to assess the specimen at the bone-cellular level.  The investigators were able to reach a diagnosis of osteosarcoma, the first time such a diagnosis has been identified in a member of the Dinosauria.

Centrosaurus Life Reconstruction

Picture credit: Michael W. Skrepnick

Originally Believed to be a Healing Fracture in the Centrosaurus Bone

The Centrosaurus bone was found in 1989 in the Dinosaur Provincial Park (Alberta).  The badly malformed bone was thought to represent a healing fracture but it was decided to investigate its unusual morphology in order to better understand the pathology.

A Cast of the Deformed Bone (Fibula) of Centrosaurus

Picture credit: Danielle Dufault (Royal Ontario Museum)

One of the co-authors of the paper, Rhianne Crowther (Trent University, Ontario), commented:

“Diagnosis of aggressive cancer like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to properly identify.  Here, we show the unmistakable signature of advanced bone cancer in 76-million-year-old horned dinosaur — the first of its kind.  It’s very exciting.”

Confirming the Diagnosis, Human Compared to a Dinosaur

To confirm the diagnosis of osteosarcoma, the bone was compared to a normal fibula from a Centrosaurus.  It was then compared to a human fibula with a confirmed case of osteosarcoma.  The Centrosaurus was an adult dinosaur and the cancer was at an advanced stage, suggesting that it probably invaded other organs and parts of its body.  The bone comes from an extensive monodominant Centrosaurus bonebed, so this dinosaur probably died with a large number of other animals in its herd during a catastrophic flood.

David Evans, a palaeontologist at the Royal Ontario Museum added:

“The shin bone shows aggressive cancer at an advanced stage.  The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of the time.  The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease.”

Seper Ekhtiari, an Orthopaedic Surgery Resident at McMaster University, who had also been involved in this study, stated:

“It is both fascinating and inspiring to see a similar multidisciplinary effort that we use in diagnosing and treating osteosarcoma in our patients leading to the first diagnosis of osteosarcoma in a dinosaur.  This discovery reminds us of the common biological links throughout the animal kingdom and reinforces the theory that osteosarcoma tends to affect bones when and where they are growing most rapidly.”

It is hoped that this research will establish a new standard for the diagnosis of unclear pathology in vertebrate fossils.  Forging links between pathology preserved in fossilised bones and human medicine will help scientists to gain a better understanding of the evolution and genetics of various diseases.

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

The scientific paper: “First case of osteosarcoma in a dinosaur: a multimodal diagnosis” by Seper Ekhtiari, Kentaro Chiba, Snezana Popovic, Rhianne Crowther, Gregory Wohl, Andy Kin On Wong, Darren H Tanke, Danielle M Dufault, Olivia D Geen, Naveen Parasu, Mark A Crowther and David C Evans published in The Lancet Oncology.

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