Semilunate Carpal

In the standard cladograms presented by the dino-to-bird enthusiasts, the Tyrannosaurs are placed just before the Maniraptors. And the most primitive "maniraptora" creatures are the Therizinosauria. Let's look at how similar/different these creatures actually are.


https://royalsocietypublishing.org/doi/full/10.1098/rspb.2009.2281

Here is a table, showing the degree of wrist flexibility of various creatures.
Guanlong wucaii (8°) is a Tyrannosauroidea

Alxasaurus elesitaiensis	(39°) is a Therizinosauria
Falcarius utahensis	(26°) is a Therizinosauria.

Table 1.

Radiale angles in various theropods. (Bold indicates specimens that we examined directly.)

taxon	angle	specimen/source
Allosaurus fragilis	2°	Chure (2001, fig. 2c)
Huaxiagnathus orientalis	18°	Hwang et al. (2004, fig. 8a)
Sinosauropteryx prima	6°	Currie & Chen (2001, fig. 8a)
Guanlong wucaii	8°	IVPP V14531
Alxasaurus elesitaiensis	39°	IVPP RV93001
Falcarius utahensis	26°	Utah Museum of Natural History, Salt Lake City, USA (UMNH) VP 12294
Caudipteryx sp.	76°	IVPP V12430
Haplocheirus	15°	IVPP V15988
Sinovenator changii	35°	IVPP V14009
Deinonychus antirrhopus	31°	YPM 5208
Eoconfuciusornis zhengi	55°	IVPP V11977
Meleagris gallopavo	59°	IVPP 1222

Notice the low numbers up to Tyrannosauroidea (Guanlong wucaii) and the much higher numbers beginning with the Therizinosauroids (Alxasaurus elesitaiensis).
These two groups are not related. The creatures labeled "maniraptora" have just been artificially tacked onto the dinosaur group.

Here is what the authors said about the discontinuity between Tyrannosauroidea and Therizinosauroids:

"Therizinosauroids are probably the most basal [primitive] maniraptoran theropods (Zanno et al. 2009). In a well-preserved left carpus of Alxasaurus (IVPP, RV93001), the SLC is strongly convex and distinctly trochlear, despite being made up of two separate ossifications (figure 2). The radiale, in contrast to that of Guanlong, [Tyrannosauroidea] is distinctly wedge-shaped."

Also see here:
http://pterosaurnet.blogspot.ca/2014/10/wrists.html

Also see Appendix 3 here:
https://www.bio.fsu.edu/James/Ornithological%20Monographs%202009.pdf