Case study documents bone cancer in 240-million-year-old stem-turtle

Bone cancer has been found in a prehistoric ancestor of the turtle that swam the seas 240 million years ago.

Morphology of Osteosarcoma on Fossil Stem-Turtle Femur: A micro-computed tomography scan shows the undisturbed
cortical bone and the extent of the periosteal mass (circled area). CB indicates cortical bone; OS, osteosarcoma;
SP, spicular outgrowth. The black scale bar represents 1 cm [Credit: JAMA Oncology (2019)]

The tumour was identified in the thigh of a primitive animal known as a shell-less stem turtle. It was highly malignant and aggressive, meaning the creature would have been in pain.

Early turtles didn't have shells and some were up to eight feet long with a beak and a very long tail. Their broad ribs, flat bodies and strong limbs were adapted for digging in the mud to bury its eggs or forage for food on the bottom of shallow waters near the shore.

The turtle lived during the Triassic at a time when the first dinosaurs were just beginning to appear - suggesting otherwise.

Yara Haridy, a master of science at the Natural History Museum, Berlin, said: "This study provides evidence tumours occurred as early as the Triassic period and that cancer is not a modern physiological defect but rather a vulnerability that is rooted deep in vertebrate evolutionary history. The appearance of the tumour in the fossilised specimen conforms with present-day osteosarcoma in humans."

Micro-computed Tomography (CT) Virtual Thin Sections of Osteosarcoma on Triassic Stem-Turtle Femur:
A, The red lines represent the locations of the thin sections shown in panels B and C. The white scale
bars on panels B and C represent 1 mm. CB indicates cortical bone; MC, medullary cavity;
OS, osteosarcoma [Credit: Jama Oncology (2019)]

Osteosarcoma is the most common type of bone cancer and can develop anywhere in the body, and most commonly strikes teenagers and young adults. Its illness helps provide more data about the history of cancer in tetrapods. This includes all species of four limbed animals - including humans, said lead author Ms Haridy.

She said: "This is a case study about a highly malignant bone tumour on the thigh bone of a shell-less stem-turtle."

The reptile was unearthed in the town of Vellberg, south west Germany, in 2013. Its deadly illness was identified under powerful microscopes and scanners.

The most affected region was at the back of the left leg, towards the hip joint. It is oldest instance of bone cancer in a reptile, bird or mammal, said the researchers.

Artistic reconstruction of Pappochelys rosinae [Credit: WikiCommons]

Named Pappochelys rosinae, meaning 'grandfather turtle' in Greek, it had a wide body, small skull and was only about eight inches long, including its long tail.

The skull was pointed with large eye sockets. There were several turtle-like features including expanded ribs and other bones that appeared to be the precursors of a shell.

Paleopathology, the study of ancient disease, is a vital way by which we understand the evolution of pathogens, immune systems, healing and the environment.

Ms Haridy said: "Cancer research has focused on its prevalence in various organisms and has found that although some animals have a high propensity for cancer, others seem to be resistant. 'The prevalence of cancer in the tree of life is certainly interesting, but its antiquity should be regarded with equal interest considering the increase in human cancer, which has been related to environmental and genetic changes, and the extreme rarity of cancer in the fossil record."

The earliest known case of bone cancer in a human was recently discovered in the toe of an early ancestor who died in Swartkrans Cave, South Africa, between 1.6 and 1.8 million years ago.

The full findings of the study were published in the journal JAMA Oncology.

Author: Tim Collins | Source: Daily Mail [February 08, 2019]