Higher resolution data
and DGS color overlays reveal that the Early Cretaceous chicken, Eogranivora, has overlooked manual and pedal digits (Fig. 1). Digit zero makes an appearance here. Fusion was much less apparent than traced. Pedal digit 1 was overlooked, despite the tracing of pedal 1.1.
Figure 1. The manus and pes of the Early Cretaceous chicken, Eogranivora. Here digit 0 makes an appearance on the manus along with vestigial digits 4 and 5. On the pes pedal digits 1 (cyan) and 5 (purple) were overlooked. Here DGS reveals them. Overlay changes ever 5 seconds. The process of fusion implied by the drawings is not yet complete under DGS.
Earlier we looked at Eogranivora and nested it with Gallus the extant chicken using low-rez data. Here even the skull is updated with plate and counter plate revealing data overlooked by original authors (Figs. 2,3 for those who don’t review updated blog posts).
Figure 2. Eogranivora skull in situ (plate and counterplate) in higher resolution.
Figure 3. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here.
Eogranivora edentulata (Zheng et al. 2018; Early Cretaceous, Yixian Fm. Aptian, 125 mya; STM35-3) was earlier referred to Hongshanornis by (Zheng et al. 2011) who found evidence for an avian crop, along with feathers, gastroliths and seeds in the present specimen. Distinct from the holotype of Hongshanornis, Eogranivora is toothless. This specimen is a direct link from the Early Cretaceous to the present day. With larger wings and a smaller body Eogranivora would have been a better flyer than extant chickens.
Figure 4.. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater. Note the length of the robust scapula.
With robust ribs
and a scapula extending back to the pelvis, Gallus, the chicken stands out from most birds. Eogranivora, if I have this right, also has robust ribs and an extended scapula (Fig. 5). Preservation is a funny thing when plates are split from counter plates. Sometimes we see the bone. Sometimes we see an impression of bone. Sometimes the bone splits down the middle and we see the inside of the bone. Here the parts of the scapula appear to be below and above the ribs, hence, my trepidation.
Figure 5. The crop, gizzard, sternum and scapulae? of Eogranivora with DGS color overlays. Some guesswork here. Some vertical bones apparently cross over and under the horizontal ribs.
Zheng X, O’Connor JK, Wang X, Wang Y and Zhou Z 2018. Reinterpretation of a previously described Jehol bird clarifies early trophic evolution in the Ornithuromorpha. Proceedings of the Royal Society B 285: 20172494
Zheng X-T, Martin LD, Zhou Z-H, Burnham DA, Zhang F-C and Miao D 2011. Fossil evidence of avian crops from the Early Cretaceous of China. Proceedings of the National Academy of Sciences. USA 108: 15 904–907