"Kayrasaurus changliensis"

[Mickey Mortimer]

Came across this when getting the supp info for the new Sinovenator paper.

http://admorph.ivpp.ac.cn/dataset/fossil/details/Reptile/a9bafefc3e05404d87c9ecd3ecd5f0d6

Apparently an upcoming taxon of therizinosauroid based on IVPP V18957, preserving at least a crushed skull and mandible. The species name may refer to Changli, a county in Hebei, China. 

Mickey Mortimer

[Tim Williams]

Mickey Mortimer <therizino...@gmail.com> wrote:

> Apparently an upcoming taxon of therizinosauroid based on IVPP V18957, preserving at least a crushed skull and mandible. The species name may refer to
> Changli, a county in Hebei, China.

_Kayrasaurus changliensis_ has arrived (though I haven't seen or read the paper yet).

Liao C-C, Freimuth WJ, Zanno LE, Xu X. (2026) A new therizinosaur from the Early Cretaceous Jehol Biota and ecomorphological patterns among early therizinosaurians. Journal of Systematic Palaeontology. 24: 2710287. doi:10.1080/14772019.2026.2710287

Abstract
Therizinosauria is a highly specialized clade of maniraptoran theropods, notable for a suite of unusual traits in late-branching taxa. These paradoxical anatomical features contributed to the complex taxonomic history of the clade, which remained unresolved until the discovery of early branching taxa. Here, we describe a new early branching species, _Kayrasaurus changliensis_, based on a nearly complete, skeletally immature specimen (IVPP V 18597) recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China. This taxon is notably larger than other penecontemporaneous Jehol therizinosaurians (at least 1.6 times larger than the second-largest taxon, _Beipiaosaurus inexpectus_) and exhibits a unique combination of features (e.g. extremely small and densely packed teeth, cervical centra markedly longer than dorsal centra, and a dorsally extended ‘lip’ on manual ungual IV). We evaluate the phylogenetic position of _K. changliensis_ using an expanded dataset with increased character and taxon sampling. Our results allow us to revise the diagnosis of _B. inexpectus_ and provide new insights into therizinosaurian evolution, provisionally recovering two subclades within Therizinosauridae that are differentiated by their manual ungual morphology. By integrating morphological traits, body mass estimates, and biomechanical data, we infer the possibility of at least two distinct ecological niches among Jehol therizinosaurians. One ecological group, represented by _B. inexpectus_ and possibly _K. changliensis_, exhibits features indicative of enhanced bite force and a more robust, less cursorial body plan. In contrast, _Jianchangosaurus yixianensis_ and _Lingyuanosaurus sihedangensis_ display traits associated with greater cursoriality and a reliance on forelimb-based foraging. _Kayrasaurus changliensis_, together with the results of our phylogenetic analysis, provides new insights into the morphological evolution and ecological adaptations of therizinosaurians in the Jehol Biota. However, further analyses and the discovery of more complete, well-preserved specimens are essential to rigorously test and refine these hypotheses. https://zoobank.org/urn:lsid:zoobank.org:pub:505B2A92-F877-490D-AA80-7CE5A21242B9

 

[Mickey Mortimer]

Notably the CT scan linked to in the paper itself is much higher resolution than the AdMorph one- https://www.morphosource.org/concern/media/000888152

Also, "The specific name changliensis is derived from Changli, a historical place name from the Three Kingdoms period, referring to the provenance of the fossil."

I gotta say I like the genus etymology- "Kayra, the god of creation in Turkic Shamanism, is the father of Erlik, the god of death, symbolizing its phylogenetic connection to Erlikosaurus; saurus, Greek for lizard." Creative and they didn't just name it Kayra!

Mickey Mortimer

[Tim Williams]

Liao et al. (2026) is the latest study to emphasize the weirdness of _Therizinosaurus_ among therizinosaurs - and _Paralitherizinosaurus_ too, which Liao &c find to be a very close relative to  _Therizinosaurus_.  The extremely long and extremely weak manual claws appear to have been useless for feeding, or for defense (Zanno 2006 doi.org/10.1671/0272-4634(2006)26[636:TPGAFO]2.0.CO;2; Lautenschlager 2014 doi: 10.1098/rspb.2014.0497.; Qin et al. 2023 doi: 10.1038/s42003-023-04552-4.).  It's therefore been suggested that the oversized claws of _Therizinosaurus_ were ornamental - so perhaps they were like the big claws of fiddler crabs, where females choose their mate based on the size and motion of the claw (although fiddler crabs are highly sexually dimorphic).

Other therizinosaur taxa have been proposed to have used their manual claws for feeding (e.g. pulling branches), and maybe also for intraspecific combat, courtship, and (as a last resort) defense (Kobayashi et al. 2025 doi.org/10.1016/j.isci.2025.112141). In that case, derived therizinosaurs like _Therizinosaurus_ and _Paralitherizinosaurus_ gave up most of these functions, and dedicated the forelimbs solely to socio-sexual display. 

BTW, when Liao &c state that their phylogenetic analysis is the first time that _ Eshanosaurus_ has been included, it's worth noting that Cau (2024 doi:10.4435/BSPI.2024.08) also included _Eshanosaurus_ in his analysis - and similarly recovered it as a basal therizinosaur.

[Mickey Mortimer]

"BTW, when Liao &c state that their phylogenetic analysis is the first time that _ Eshanosaurus_ has been included, it's worth noting that Cau (2024 doi:10.4435/BSPI.2024.08) also included _Eshanosaurus_ in his analysis - and similarly recovered it

 as a basal therizinosaur."

Clark et al. (2004) included it way back in their chapter of The Dinosauria 2nd Edition. Pretty obscure book admittedly... ;)  It really doesn't mean much without a representative sample of basal sauropodomorphs (Cau doesn't include any bagualosaurs).

Speaking of their phylogenetic analysis, when I run their matrix in PAUP*, bohlini (which they excluded a priori) makes a polytomy of therizinosauroids more derived than "Fukuivenator". And in case anyone thinks their Figure 12 indicates they support therizinosaurs sister to oviraptorosaurs, then alvarezsauroids, nope. They just didn't include any paravians. Similarly, it's not really evidence of a therizinosaurian "Fukuivenator" as the only non-maniraptoran used is the outgroup Tyrannosaurus (TERRIBLE outgroup not representative of basal tyrannoraptoran anatomy...). So yeah, I'm not surprised "Fukuivenator" is closest to Falcarius when e.g. Ornitholestes or anything in that grade isn't available. Also, their oviraptorosaur sample is Incisivosaurus, Microvenator, Oviraptor and Citipati and their alvarezsauroid sample in Alvarezsaurus, Shuvuuia and Mononykus. I know it was too late for the good Alnashetri, but how about Haplocheirus, Caudipteryx and Guanlong instead of Alvarezsaurus, Microvenator and Tyrannosaurus? 

Mickey Mortimer