Schematic representation of changing joint surfaces and articular cartilage thickness with increasing size in mammals and archosaurs.

<p>Our data suggest that as mammals increase in size, the joint region narrows and the articular cartilage becomes relatively thinner, producing convex and well-developed subchondral bone surfaces. For archosaurs, our data suggest that with increasing size the joint region expands while the articular cartilage remains thick, producing relatively flat and less convex subchondral bone surfaces.