Life ain’t easy. For animals, plants, and organisms of all kinds, there exists a constant threat of injury and disease. Fortunately, these unfortunate occurrences sometimes leave evidence in fossils that can inform us of the lives – and even deaths – of species from long ago. The study of this evidence is called Paleopathology.
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When Bodies Go Wrong
Pathology is the study of the causes and effects of injury and disease. The same thing can be done on fossils, in which case it’s called paleopathology.
Of course, injury and disease can affect just about any tissue in any life form, from organs to skin to leaves, but since most soft tissues don’t regularly fossilize, paleopathology typically focuses on hard tissues: shell, wood, and especially bone. And since this episode’s special guest, Laura Emmert, is – like us – a vertebrate paleontologist, most of our discussion centered on bone.
As Laura explains, paleopathology often involves detecting where something has gone wrong in a fossil tissue. Sometimes it’s as simple as a fracture or indentation in a bone where it was broken, but often researchers are looking for abnormal tissue activity; when a broken bone heals, new bone tissue will form a characteristic spongy texture, and might reconstruct the bone in an unusual way, healing at an odd angle or fusing multiple bones together. Disease can affect the balance between bone growth (cells producing new bone) and bone resorption (cells recycling bone) resulting in bone being overly thick, thin, or even pockmarked by disease.
Unfortunate, but informative!
Suffering an injury or disease is obviously a bad time for the organism, but it can be very enlightening for us. Research on paleopathology can reveal where one animal chomped on another, what insects grazed on leaves, or what kinds of diseases impacted dinosaurs. At our favorite site, the Gray Fossil Site, fossils have revealed evidence of gators biting turtles, insects inducing galls in plant stems, and tapirs living to such ripe old ages that their teeth wore all the way down and their joints became heavily arthritic.
Of course, it can be very difficult to determine fine details. Was this injury the result of an epic fight or a clumsy accident? Is it unhealed because it killed the animal, or did the animal die shortly afterward of unrelated causes before the injury had time to heal? Often, questions like these are impossible to answer. But our techniques continue to improve.
DinoSores: an annotated bibliography of dinosaur paleopathology and related topics (technical)
A century of paleopathology – An overview of the history of study (semi-technical)