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Palaeopathology part I: cancer – an ancient disease

Dr. Rainer Schoch is curator for amphibians and reptiles of the Palaeozoic and Mesozoic.

Palaeontology meets medicine: Bone cancer diagnosed in a 240 myr old turtle ancestor

Sometimes it can be a good investment to excavate in long-known quarries. For instance, a highly unexpected find was made in a limestone quarry near Vellberg, when our palaeontological team excavated Pappochelys rosinae, later referred to as Grandpa Turtle. This 30 cm long reptile is dwarfed by its 3–6 m long contemporaries, giant amphibians and large carnivorous reptiles. In a sample of thousands of bones, the skeletal remains of Grandpa Turtle form rare but unspectacular picks.

Pappochely rosinae – fossil: on the left the long tail, to the right the front part.

The Patient: Pappochelys rosinae

Pappochelys was first reported in 2015 and fully described in 2018, when its complete skeleton became known. Its discovery yielded many new and some highly perplexing details on the origin of turtles. Together with the geologically younger stem-turtles Odontochelys and Eorhynchochelys, it helped to solve the century-old mystery of turtle origins.

Reconstruction model of Pappochelys. (R. Schoch)

In life, Grandpa Turtle must have appeared like a small, stout lizard, but its skeleton clearly reveals a suite of turtle features: short and broadened ribs as forerunners of the back shell (carapace), shoulder blade rod-like, trunk vertebrae reduced to nine, and a range of thickend bony rods that would later fuse to form the belly shell (plastron). Contrasting later turtles, Pappochelys retained regular teeth and a delicate skull, much like that of modern tuataras and iguanas.

Diagnosis: Bone tumor!

With a geological age of 240 million years, Pappochelys was distinctly older than its Chinese relatives Odontochelys and Eorhynchochelys. Yet Grandpa Turtle is not only a star in geological and evolutionary terms, but now also yields highly interesting medical data! One Pappochelys femur (upper leg bone) had puzzled us by having a remarkable bone tumor.

Upper leg bone of Pappochelys rosinae, above: healty bone, below: with bone tumor, marked by red arrow. (R. Schoch)

My colleagues Yara Haridy and Florian Witzmann (Museum für Naturkunde Berlin) suspected a bone disease when they decided to apply computer tomography to the enigmatic specimen. And indeed, the micro CT images revealed bone tissue structures that are consistent with bone cancer (osteosarcoma). Further experts from medicine, radiologist Patrick Asbach (Charité Berlin) and palaeo-pathologist Bruce Rothschild (Pittsburgh) confirmed the bone tumor diagnosis in Pappochelys.

With a geological age of 240 million years, Pappochelys was distinctly older than its Chinese relatives Odontochelys and Eorhynchochelys. Yet Grandpa Turtle is not only a star in geological and evolutionary terms, but now also yields highly interesting medical data! One Pappochelys femur (upper leg bone) had puzzled us by having a remarkable bone tumor. My colleagues Yara Haridy and Florian Witzmann (Museum für Naturkunde Berlin) suspected a bone disease when they decided to apply computer tomography to the enigmatic specimen. And indeed, the micro CT images revealed bone tissue structures that are consistent with bone cancer (osteosarcoma). Further experts from medicine, radiologist Patrick Asbach (Charité Berlin) and palaeo-pathologist Bruce Rothschild (Pittsburgh) confirmed the bone tumor diagnosis in Pappochelys.


Reconstruction model – the left femur (red) has a remarkable bone tumor. (Brian Engh)

This evidence forms the oldest osteosarcoma in the fossil record and in amniote land vertebrates. The results are published in the renowned medical journal JAMA Oncology, forming a further bridge over the wide gap between two disciplines that could hardly be more different: palaeontology and medicine, which fuse in this area to form the fascinating science of Palaeopathology.


References

Haridy Y, Witzmann F, Asbach P, Schoch RR, Fröbisch N, Rothschild BM. Triassic Cancer—Osteosarcoma in a 240-Million-Year-Old Stem-Turtle. JAMA Oncol. Published online February 07, 2019. doi:10.1001/jamaoncol.2018.6766

Rainer R. Schoch & Hans-Dieter Sues (2018) Osteology of the Middle Triassic stem-turtle Pappochelys rosinae and the early evolution of the turtle skeleton, Journal of Systematic Palaeontology, 16:11, 927-965, DOI: 10.1080/14772019.2017.1354936

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