Huadanosaurus
| Huadanosaurus Temporal range: Early Cretaceous (Barremian),
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| Photograph (a) and line drawing (b) of the holotype specimen | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Sinosauropterygidae |
| Genus: | †Huadanosaurus Qiu et al., 2025 |
| Species: | †H. sinensis
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| Binomial name | |
| †Huadanosaurus sinensis Qiu et al., 2025
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Huadanosaurus is an extinct genus of compsognathid-like theropod dinosaurs from the Early Cretaceous Yixian Formation of China. The genus contains a single species, H. sinensis, known from a nearly complete skeleton.[1]
Discovery and naming
[edit]The Huadanosaurus holotype specimen, IVPP V14202, was discovered in outcrops of the Yixian Formation (Dawangzhangzi bed) in Lingyuan of Liaoning Province, China. The specimen consists of a nearly complete skeleton preserved on a slab, missing the feet and the end of the tail.[1] It was originally attributed to the related genus Sinosauropteryx.[2]
In 2025, Qiu et al. described Huadanosaurus sinensis as a new genus and species of sinosauropterygid theropods based on these fossil remains. The generic name, Huadanosaurus, combines "Huadan"—a Chinese word referring to the birthday of a great person or institution—with the Ancient Greek σαῦρος (sauros), meaning "lizard". This honors the 70th anniversary of the founding of the Academic Divisions of the Chinese Academy of Sciences (CASAD). The specific name, sinensis, is derived from the Latin word sina, which refers to China.[1]
Description
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Qiu et al. (2025) identified the Huadanosaurus holotype as belonging to a probable immature individual based on the unfused vertebral neurocentral sutures and scarred bone surfaces. Furthermore, its skull measuring over 10 cm (3.9 in) long is fairly large in relation to the rest of the body.[1]
Colouration
[edit]In 2010, Fucheng Zhang and colleagues examined the fossilized feathers of several dinosaurs and early birds, and found evidence that they preserved melanosomes, the cell components that give the feathers of modern birds their colour. Among the specimens studied was a previously undescribed specimen of Sinosauropteryx, IVPP V14202,[2] though this specimen is now the holotype of Huadanosaurus.[1] By examining melanosome structure and distribution, Zhang and colleagues were able to confirm the presence of light and dark bands of colour in the tail feathers of this specimen (now the holotype of Huadanosaurus) like that of a red panda. Furthermore, the team was able to compare melanosome types to those of modern birds to determine a general range of colour. From the presence of phaeomelanosomes, spherical melanosomes that make and store red pigment, they concluded that the darker feathers of this specimen were chestnut or reddish brown in colour.[2]
Classification
[edit]Huadanosaurus is similar to several dinosaurs historically called the Compsognathidae. However, a 2024 analysis by Andrea Cau proposed that these taxa did not form a natural monophyletic clade and that some are juveniles of larger tetanurans.[3] To test this hypothesis, Qiu et al. (2025) scored Huadanosaurus in Cau's "Ontogenetic State Partitioning" (OSP) phylogenetic matrix and the more traditional "Theropod Working Group" (TWiG) matrix.[4] Both phylogenetic analyses found support for a natural group of all Jehol Biota (Early Cretaceous) compsognathid-like theropods (Sinosauropteryx spp., Huaxiagnathus, and Sinocalliopteryx) as well as the Brazilian Mirischia. Using the OSP matrix, Huadanosaurus was recovered as the sister taxon to Mirischia and Sinocalliopteryx. Since Compsognathus was recovered outside of this group, Qiu et al. opted to use the name Sinosauropterygidae for this group. These results are displayed in Topology A below. Using the TWiG matrix, Huadanosaurus was found to be the sister to the group formed by Compsognathus and Sinosauropteryx spp., as shown in Topology B below.[1]
Paleoecology
[edit]Several fragments of mammal bones, including eutherians and eutriconodonts, were found in the abdominal cavity region of Huadanosaurus. Based on the disarticulated but associated, well-preserved condition of the mammal remains, the individuals were likely swallowed whole. This further implies that Huadanosaurus individuals were incapable of firmly grasping with their hands to tear or bite prey items. Most Mesozoic mammals were likely nocturnal, suggesting Huadanosaurus was as well.[1]
References
[edit]- ^ a b c d e f g Qiu, Rui; Wang, Xiaolin; Jiang, Shunxing; Meng, Jin; Zhou, Zhonghe (2025-02-22). "Two new compsognathid-like theropods show diversified predation strategies in theropod dinosaurs". National Science Review. doi:10.1093/nsr/nwaf068. ISSN 2095-5138.
- ^ a b c Zhang, F.; Kearns, S.L.; Orr, P.J.; Benton, M.J.; Zhou, Z.; Johnson, D.; Xu, X.; Wang, X. (2010). "Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds" (PDF). Nature. 463 (7284): 1075–1078. Bibcode:2010Natur.463.1075Z. doi:10.1038/nature08740. PMID 20107440. S2CID 205219587.
- ^ a b Cau, Andrea (2024). "A Unified Framework for Predatory Dinosaur Macroevolution" (PDF). Bollettino della Società Paleontologica Italiana. 63 (1): 1–19. doi:10.4435/BSPI.2024.08 (inactive 2025-02-24). ISSN 0375-7633.
{{cite journal}}: CS1 maint: DOI inactive as of February 2025 (link) - ^ a b Brusatte, Stephen L.; Lloyd, Graeme T.; Wang, Steve C.; Norell, Mark A. (2014-10-20). "Gradual Assembly of Avian Body Plan Culminated in Rapid Rates of Evolution across the Dinosaur-Bird Transition". Current Biology. 24 (20): 2386–2392. doi:10.1016/j.cub.2014.08.034.
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