Undetermined undetermined Li, Xing, Jiang, Liu, Brusate & Bi, 2025, gen. et

Neotheropoda gen. et sp. indet. Material: LZ0895 —partial postcranial skeleton, including heavily broken trunk and sacral vertebrae, broken pelvic girdle, and partial hindlimbs from both sides of the body. Type locality and horizon: The material is from a single locality in the Shawan Member of the Lufeng Formation, Heilongtan, Lufeng County, Yunnan Province, southwestern China. Diagnosis: A skeletally immature non-averostran neotheropod that differs from other neotheropods by the following unique combination of character states (autapomorphies indicated with an asterisk): a tibiofibular crest more posteriorly developed than the medial condyle in the femur; a ridge on the medial surface of the pubic peduncle of the ischium*; and strongly excavated prezygapophyseal and postzygapophyseal spinodiapophyseal fossae, with accessory laminae on the anterior trunk neural arches. Description Vertebra Trunk vertebrae and ribs Eight damaged trunk vertebrae are preserved, including five free neural arches and three articulated centra. Some fragments of neural spines also are preserved (Fig. 3). One fragment is probably adhered to another neural arch, covered by matrix and glue, resulting in ambiguous identification (Fig. 3A, F, K). We identified these neural arches as belonging to the anterior trunk vertebrae (Fig. 3A–C, F–H, K–M) and the mid-posterior trunk vertebrae (Fig. 3D–E, I, J, N, O). The centra are identified as mid-posterior trunk vertebrae (Fig. 3T, U). Two anterior trunk neural arches are highly pneumatic (Fig. 3A, B, F, G, K and L). In dorsal view, the prezygapophyseal spinodiapophyseal and postzygapophyseal spinodiapophyseal fossae are well-developed and deep (Fig. 3K–L), similar to Ceratosaurus (Madsen and Welles 2000: pl. 16); Tanos simonatoi also presents a similar structure in the axis (Delcourt and Vidoi Iori 2020). The prezygapophyseal spinodiapophyseal fossae are large and contain subfossae with foramina inside (Fig. 3K), a condition that differs from Dilophosaurus oetherilli (Marsh and Rowe 2020) and coelophysoids (Britt 1993). No well-developed prezygapophyseal spinodiapophyseal and postzygapophyseal spinodiapophyseal fossae have been recorded in Dilophosaurus oetherilli (Britt 1993, Marsh and Rowe 2020). Another anterior trunk neural arch is also severely damaged, lacking the prezygapophysis, poszygapophysis, diapophysis, and paraphysis. However, it can still be observed that the base of the diapophysis inclines anteroventrally and projects dorsally (Fig. 3B–G). The prezygapophyseal and postzygapophyseal spinodiapophyseal fossae are also present on the dorsal surface of the neural arch but are much smaller and shallower than those in another anterior trunk neural arch described above (Fig. 3L). The most posterior of preserved anterior trunk neural arches is the best preserved (Figs 3C, H, M, 4). Only the spinodiapophyseal fossa occurs on the dorsal surface (Fig. 3I), as seen in Dilophosaurus oetherilli (Marsh and Rowe 2020). The postzygapophyses of the previous vertebrae are articulated to the prezygapophyses of this vertebra (Figs 3C, H, M, 4). The prezygapophyseal centrodiapophyseal fossa is relatively small, deep, and narrows into a small foramen (labelled as ‘foramen 1’; see Fig. 4A) between the prezygadiapophyseal lamina and the anterior centrodiapophyseal lamina (Figs 3C, F, 4A). Although the diapophysis is broken, the centrodiapophyseal fossa is clearly large and deep (Figs 3C, F, 4A, B), with no apparent foramina. The postzygapophyseal centrodiapophyseal fossa is shallower than the prezygapophyseal centrodiapophyseal fossa and contains two foramina in its deepest portion (labelled as ‘foramen 2 and 3’; see Fig. 4B). Additionally, below the postzyapophysis, a foramen is observed within the articulation facet with the prezyapophysis (labelled as ‘foramen 4’; see Fig. 4B). The paraphysis is visible on this neural arch, and may have been present on the centrum, which lacks the posterior centrodiapophyseal lamina. CT cross-sections reveal the internal morphology of one anterior trunk neural arch, showing a thin cortex on the external surface (Fig. 4C–F). Loose trabecular bone fills the internal space of the neural spine and the neural arch dorsal to the neural canal (Fig. 4C–F). Notably, in the posterior half of the neural arch, there is a vacuity approximately 5 mm in diameter, occupying most of the transverse width at the posterior end of the neural arch (Fig. 4F). The resolution of the CT data is not high enough to determine the connections between these foramina and the internal vacuities. However, foramina 2 and 4 appear to connect to intertrabecular spaces (Fig. 4C, D). The lengths of the mid-posterior trunk centra exceed the heights of the anterior articular surfaces (Supporting Information, Table S1). Both anterior and posterior articular faces of these centra are similar in size and shape. The trunk centra are amphicoelous, while in some other early neotheropods, such as Cryolophosaurus ellioti (Smith et al. 2007), Dilophosaurus oetherilli (Welles 1971), and Gojirasaurus quayi (Carpenter 1997), they are amphiplatyan. Striations that extend along the long axis of the centrum are present on the rims of both articular ends of each centrum. The centrum is relatively short anteroposteriorly with a length–height ratio comparable to that of averostrans such as Eoabelisaurus mefi and Piatnitzkysaurus floresi, and is considerably lower than in coelophysids (Fraas 1913, Raath 1969, 1977), Dilophosaurus oetherilli (Welles 1971), and Cryolophosaurus ellioti (Smith et al. 2007). The trunk vertebral centra of LZ0895 lack a ventral keel, which is variable in early neotheropods (Ezcurra et al. 2021). The centra columns present no foramina on the surface, but some small and shallow depressions are found (Fig. 3T, U). We interpret these depressions as a result of taphonomy. CT cross-sections show a thick layer of cortex forming the ventral margin of the centrum, thickest at the midpoint of its length and tapering toward the anterior and posterior ends. A very thin cortex layer surrounds the neural canal (Fig. 5G), with dense trabecular bone occupying most internal spaces of the centrum (Fig. 5G). The two preserved mid-posterior trunk neural arches are also damaged, as neural spines are broken from their bases and all diapophyses have been severely damaged (Fig. 5A–F). Although the prezygapophysis is damaged in all neural arches, they are still clear enough to determine that they were short in length (Fig. 3D, E). The distal ends of the postzygapophyses of previously articulated trunk vertebrae are partially preserved in these two mid-posterior neural arches (Fig. 3D, E). One trunk neural arch of LZ0895 exhibits a hyposphene (Fig. 5B). Furthermore, a trunk vertebra has two posteriorly attached ribs, though only the proximal ends are preserved (Fig. 3D, E). The ribs are slender, with slightly damaged rib heads. Vertebrallaminaearewelldevelopedinthetrunkvertebrae.The bases of spinoprezygapophyseal and spinopostzygapophyseal laminae are visible on the dorsal part of the neural arch (Fig. 3N, O). The lateral neural arch laminae shift according to the position of the parapophysis, while the posterior centrodiapophyseal lamina remains consistent. In the posterior trunk vertebrae, the parapophysisisonthediapophysis,dividingtheprezygapophyseal lamina into an anterior horizontal prezygoparapophyseal lamina and a posterior paradiapophyseal lamina (see Fig. 3E). The prezygoparapophyseal lamina is noticeably shorter than the posterior centrodiapophyseal and postzygodiapophyseal laminae, along with the anterior centroparapophyseal lamina. Thus, the prezygopophyseal centrodiapophyseal fossa is much smaller compared to the postzygopophyseal centrodiapophyseal fossa, which expands more extensively laterally. One of two mid-posterior trunk vertebrae was CT scanned (Figs 3E, 5A–F). Based on observation of the specimen and a 3D model reconstructed from the cross sections, several foramina are recognized (Fig. 5A, B). The foramen in the centrodiapophyseal fossa (labelled as ‘foramen 1’; see Fig. 5A, E) is not very obvious on the bone surface (Fig. 5A). The prezygapophyseal centrodiapophyseal fossa is narrow and deep, but there are no foramina. The postzygapophyseal centrodiapophyseal fossa is large and deep, housing a foramen (labelled as ‘foramen 2’; see Fig. 5B) in its deepest part, as in the anterior trunk vertebra described above. Another foramen is located on the lateral surface of the hyposphene (labelled as ‘foramen 3’; see Fig. 5B). In CT cross-sections, the mid-posterior trunk vertebra has the same thin cortex on the external surface of the neural arch as in the anterior trunk vertebra (Fig. 5C–F). The internal spaces of these vertebrae are also formed by trabecular bone (Fig. 5C–F). The trabecular bone is more dense than that in the anterior trunk vertebrae, with the exception of the base of the diapophysis (Fig. 5C, E). The foramen 1 in the centrodiapophyseal fossa connects the vacuity in the diapophysis (Fig. 5E). Foramina 2 and 3 do not lead to any internal vacuities in the CT cross-sections. However, the prezygapophyseal centrodiapophyseal fossa tapers into a canal approximately 1 mm in width, connecting the internal space of the neural arch (Fig. 5C, F). Sacral vertebrae The sacrum is partially preserved, comprising four vertebral centra (Fig. 6), indicating that LZ0895 has a minimum of four sacral vertebrae, although the total number of sacrals is unclear. All sacral centra are amphiplatyan and articulated. Partially crushed neural arches of the second and third sacral vertebrae are preserved (Fig. 6A, B). In the fourth sacral vertebra, only the anterior part of the centrum is preserved. We identified the sacral vertebrae following the rationale given by Nesbitt (2011). We interpret the specimen as including the dorsosacral and first primordial sacral vertebra with confidence (Fig. 6A, B), but it is uncertain