Updated February 5, 2018 with higher resolution data of the skull. Not much changed. Eogranivora is still a chicken sister.
This was predicted
by the large reptile tree (LRT, 1054 taxa, subset Fig. 3) and overlooked by the original authors due to a lack of an accurate tracing of the skull. Extant birds had their origin in the Early Cretaceous… they just have not been discovered there, until now.
Figure 1. Eogranivora from Zheng et al. 2018 with DGS colors added and reconstructed. Except for the longer wings and straight rostrum, most traits found here are also found in Gallus the chicken (figure 2).
Figure 1b. Eogranivora skull in situ (plate and counterplate) in higher resolution. Colors correspond to reconstructed skull in figure 1c. Colors sure do clarify skulls like this one.
Figure 1c. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here. It’s still a chicken sister.
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.
Figure 2. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater.
included Gallus the chicken (Fig. 2) in their taxon list, but failed to nest the two taxa together… even after noting that Eogranivora was a seed eater. So, this one cannot be attributed to taxon exclusion, but taking a look at their tracing of the specimen (Fig. 1) indicates they put little to no effort into deciphering the crushed bones of this complete and articulated specimen. They could have used a little DGS, which always comes with a reconstruction (Fig. 1 skull, pes).
With larger wings and a smaller body
Eogranivora would have been a better flyer than extant chickens. And that’s to be expected.
Figure 3. Eogranivora nests with Gallus the chicken in the LRT, confirming the origin of Ornithuromorpha in the Early Cretaceous, which makes it that much easier to have highly derived penguins appear in the Paleocene.
You may remember
the highly derived penguins first appear in the Paleocene. The appearance of volant chickens in the Early Cretaceous makes this easier (more gradual), and falsifies the earlier widely-held hypothesis of a fast radiation of extant birds shortly after the K-T extinction event.
This could have been a big news event.
Unfortunately, it falls to bloggers to make the importance of this fossil widely known.
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