Reply to Foth: Preserved cartilage is rare but not absent: Troodontid sternal plates are absent, not rare

Foth (1) critiques the conclusions of a previous work by Zheng et al. (2), which describes the complete absence of sternal elements in Anchiornis and Sapeornis. Although initially we were equally skeptical, we feel that the evidence continues to be strongly compelling, and we thank Foth (1) for giving us the opportunity to further address potential skepticism. First, it is argued that most theropod dinosaurs lack ossified sternal elements; this may be true of basal members of the clade and indeed these elements are rare. However, recent work on derived maniraptoran theropods strongly suggests that these elements are present in most taxa but ossify late in skeletal …

↵¹To whom correspondence should be addressed. Email: zhouzhonghe{at}ivpp.ac.cn.