Exquisite Juvenile Specimen of Basal Bird Sapeornis Found from Lower Cretaceous China

A new juvenile specimen of Sapeornis (Pygostylia: Aves) from the Lower Cretaceous of Northeast China and allometric scaling of this basal bird

Authors:

1. HANYONG PU (a)

2. HUALI CHANG (a)

3. JUNCHANG LÜ (b)

4. YANHUA WU (a)

5. LI XU (a)

6. JIMING ZHANG (a)

7. SONGHAI JIA (a)

Affiliations:

a. Henan Geological Museum, No. 18 Jinshuidong Road, Zhengdong New District, 450016 Zhengzhou, China

b. Institute of Geology, Chinese Academy of Geological Sciences, 100037 Beijing, China

Abstract:

The discovery of an extremely well preserved new juvenile specimen of Sapeornis provides more anatomical information about this basal avian, and documents the first avian specimen from the Jehol Biota with detailed foot-pad integument preserved. This is the first Sapeornis specimen with a well preserved carpal X, astragalus and calcaneum. Seven major skeletal components from five well preserved juvenile and adult skeletons of Sapeornis were measured. The allometric differences associated with growth are shown to be distinct; all linear regressions resulted in high correlation coefficients consistent with a single growth series. The number of sacral vertebrae and free caudal vertebrae vary during ontogeny, and this may indicate that all the specimens can be assigned to a single species: Sapeornis chaoyangensis.