New light shed on the early evolution of  limb-bone growth plate and bone marrow

• The production of blood cells (haematopoiesis) occurs in the limb bones of most tetrapods but is absent from the fin bones of ray-finned fish. When did long bones start producing blood cells? Recent hypotheses suggested that haematopoiesis migrated into long bones prior to the water-to-land transition and protected newly-produced blood cells from harsher environmental conditions. However little fossil evidence to support these hypotheses has been provided so far. Observations of the humeral microarchitecture of stem-tetrapods, batrachians and amniotes were performed using classical sectioning and three-dimensional synchrotron virtual histology. They show that Permian tetrapods seem to be among the first to exhibit a centralised marrow organisation which allows haematopoiesis as in extant amniotes. Not only does our study demonstrate that long-bone haematopoiesis was probably not an exaptation to the water-to-land transition but it sheds light on the early evolution of limb-bone development and the sequence of bone-marrow functional acquisitions.

Subject headings

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Keyword

three-dimensional virtual palaeohistology

tetrapod terrestrialisation

haematopoiesis

amphibians

stem amniotes

Permian

propagation phase-contrast synchrotron microtomography.

Publication and Content Type

ref (subject category)

art (subject category)