(A) (B) (C)
(D)
(a)
(b)
(c)
(d)
FIGURE 13.8. The primitive triconodont mammal Yanoconodon allini from the Lower Cretaceous of China, which
still retains its ear bones attached to its lower jaw. (A) Photograph of the original articulated specimen. (B and C)
Sketch of the skeleton, labeling the bones, and a reconstruction of the skeleton. (D) Detailed diagrams of the lower
jaw, showing the ring of ear bones still attached to the lower jaw while functioning for hearing. Specimen (a) is the
jaw of the primitive Triassic mammal Morganucodon; (b) is Yanoconodon, with a detail of the ear bones shown in
(c) Diagram (d) is the lower jaw of the triconodont Repenomamus. For further details, see Luo et al. (2007:288–293).
(Courtesy Zhexi Luo/Carnegie Museum of Natural History)