I may be the last to the party on this one,
but I don’t think anyone yet has made the ornithomimosaur nesting or found four fingers in Compsognathus.
I found a higher resolution image
of the holotype of Compsognathus (Figs. 1-3) and so was able to better understand the specimen. That’s always a fascinating experience — finding errors, even if they are your own. A few changes were made to the face (Figs. 1,2), foot and hand, which now has three relatively robust fingers (Fig. 2) and a fourth vestige.
The new finger data is particularly interesting
because the color data does not have two large phalanges (2.1, 2.2) found in the grayscale image of Gishlick and Gauthier 2007 (Fig. 3). IMHO the right hand is completely buried, except for ungual 1. The remaining elements create a complete basal theropod manus.
In phylogenetic analysis,
a subset of the large reptile tree (Fig. 4) moves Compsognathus to the Struthiomimus clade at the base of the microraptor/tyrannosaur clade. With such similar skull and overall shapes, it is easy to see how that happened.
Gishlick AD and Gauthier JA 2007. On the manual morphology of Compsognathus longipes and its bearing on the diagnosis of the Compsognathidae. Zoological Journal of the Linnean Society 149: 569–581.
Ostrom JH 1978. The osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.