Diaphragm much older than expected

The diaphragm is unique to mammals and our most important respiratory muscle. Scientists at the University of Bonn and the Zoological Research Museum Alexander Koenig examined breathing in extinct caseids and came to the surprising conclusion that the diaphragm evolved about 50 million years earlier than previously assumed. The study just appeared in the “Annals of the New York Academy of Sciences”.

“Evolution has brought up some weird animals, such as the caseids.” says Dr. Markus Lambertz, zoologist at the University of Bonn and the Museum Koenig. Caseids are “mammal-like” reptiles that lived about 300-250 million years ago. Especially the barrel-shaped trunk got Dr. Lambertz’ attention. How did these reptiles breathe? Exceptional joints impeded rib motility and allowed for only limited inhalation. Calculations revealed that the ventilatory system was not that effective, but still sufficient for a sedentary grazer. Everything appeared reasonable, because ever since the their first description in 1910 it was assumed that these large herbivores were something like “cows” of the Paleozoic.

More informations: https://bonn.leibniz-lib.de/en/zfmk/presse/diaphragm-much-older-than-exp...

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