Undetermined undetermined, Li, Hongqing, Xing, Xu, Jiang, Juan, Liu, Jianrong, Brusate, Stephen L. & Bi, Shundong, 2025

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 View Figure 3 ). One fragment is probably adhered to another neural arch, covered by matrix and glue, resulting in ambiguous identification ( Fig. 3A, F, K View Figure 3 ). We identified these neural arches as belonging to the anterior trunk vertebrae ( Fig. 3A–C, F–H, K–M View Figure 3 ) and the mid-posterior trunk vertebrae ( Fig. 3D–E, I, J, N, O View Figure 3 ). The centra are identified as mid-posterior trunk vertebrae ( Fig. 3T, U View Figure 3 ).

Two anterior trunk neural arches are highly pneumatic ( Fig. 3A, B, F, G, K and L View Figure 3 ). In dorsal view, the prezygapophyseal spinodiapophyseal and postzygapophyseal spinodiapophyseal fossae are well-developed and deep ( Fig. 3K–L View Figure 3 ), 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 View Figure 3 ), 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 View Figure 3 ). 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 View Figure 3 ).

The most posterior of preserved anterior trunk neural arches is the best preserved ( Figs 3C, H, M View Figure 3 , 4 View Figure 4 ). Only the spinodiapophyseal fossa occurs on the dorsal surface ( Fig. 3I View Figure 3 ), 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 View Figure 3 , 4 View Figure 4 ). The prezygapophyseal centrodiapophyseal fossa is relatively small, deep, and narrows into a small foramen (labelled as ‘foramen 1’; see Fig. 4A View Figure 4 ) between the prezygadiapophyseal lamina and the anterior centrodiapophyseal lamina ( Figs 3C, F View Figure 3 , 4A View Figure 4 ). Although the diapophysis is broken, the centrodiapophyseal fossa is clearly large and deep ( Figs 3C, F View Figure 3 , 4A, B View Figure 4 ), 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 View Figure 4 ). Additionally, below the postzyapophysis, a foramen is observed within the articulation facet with the prezyapophysis (labelled as ‘foramen 4’; see Fig. 4B View Figure 4 ). 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 View Figure 4 ). Loose trabecular bone fills the internal space of the neural spine and the neural arch dorsal to the neural canal ( Fig. 4C–F View Figure 4 ). 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 View Figure 4 ). 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 View Figure 4 ).

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 View Figure 3 ). 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 View Figure 5 ), with dense trabecular bone occupying most internal spaces of the centrum ( Fig. 5G View Figure 5 ).

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 View Figure 5 ). 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 View Figure 3 ). The distal ends of the postzygapophyses of previously articulated trunk vertebrae are partially preserved in these two mid-posterior neural arches ( Fig. 3D, E View Figure 3 ). One trunk neural arch of LZ0895 exhibits a hyposphene ( Fig. 5B View Figure 5 ). Furthermore, a trunk vertebra has two posteriorly attached ribs, though only the proximal ends are preserved ( Fig. 3D, E View Figure 3 ). 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 View Figure 3 ). 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 View Figure 3 ). 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 View Figure 3 , 5A–F View Figure 5 ). Based on observation of the specimen and a 3D model reconstructed from the cross sections, several foramina are recognized ( Fig. 5A, B View Figure 5 ). The foramen in the centrodiapophyseal fossa (labelled as ‘foramen 1’; see Fig. 5A, E View Figure 5 ) is not very obvious on the bone surface ( Fig. 5A View Figure 5 ). 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 View Figure 5 ) 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 View Figure 5 ). 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 View Figure 5 ). The internal spaces of these vertebrae are also formed by trabecular bone ( Fig. 5C–F View Figure 5 ). 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 View Figure 5 ). The foramen 1 in the centrodiapophyseal fossa connects the vacuity in the diapophysis ( Fig. 5E View Figure 5 ). 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 View Figure 5 ).

Sacral vertebrae

The sacrum is partially preserved, comprising four vertebral centra ( Fig. 6 View Figure 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 View Figure 6 ). 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 View Figure 6 ), but it is uncertain whether the third and fourth sacral vertebrae represent the second primordial sacral vertebra, an inserted sacral vertebra, or the caudosacral vertebra. For the purposes of this study, we will refer to them simply as the third and fourth sacral vertebrae. The sacral series displays slight dorsal curvature ( Fig. 6A, B View Figure 6 ). The centra of these vertebrae are anteroposteriorly longer than they are tall and posses a transverse concavity. The posterior three centra are partially coosified ( Fig. 6A, B View Figure 6 ), suggesting skeletal immaturity of this individual. However, in Dilophosaurus oetherilli none of the specimens with a preserved sacrum exhibit sacral centra fusion, including the older individual (UCMP 77270) as determined by Marsh and Rowe (2020).

The dorsosacral vertebra is represented solely by its centrum ( Fig. 6A, B View Figure 6 ), which is smaller in size than the trunk vertebrae both in height and length. The articular surfaces are subelliptical, with the anterior surface wider than the posterior surface ( Fig. 6E View Figure 6 ). The ventral margin is concave posterodorsally in lateral view ( Fig. 6A, B View Figure 6 ), while the centre is constricted medially in ventral view ( Fig. 6D View Figure 6 ). Striations parallel to the long axis of the centrum are present near the margins at the anterior end ( Fig. 6D View Figure 6 ).

The first primordial and the third sacral vertebrae of LZ0895 are tightly articulated, although the suture is still visible ( Fig. 6A, B View Figure 6 ). The neural arches are damaged and distorted and the neural spines are missing. The zygapophyses are also tightly articulated between the two vertebrae. The left ribs of both vertebrae are attached to the left ilium ( Fig. 6C, D View Figure 6 ), although it remains uncertain whether they were coossified with the ilia ( Raath 1990, Tykoski 2005). Furthermore, the first primordial sacral vertebra features a broken and prominent sacral rib on its left side that is coossified with its articular surface on the dorsolateral corner of the centrum ( Fig. 6A View Figure 6 ). Notably, this rib appears elongated and oval-shaped when viewed laterally ( Fig. 6A View Figure 6 ). The third sacral vertebra is shorter anteroposteriorly and dorsoventrally than the first primordial sacral vertebra (Supporting Information, Table S1). At the anterior top of the centrum, it has sturdy sacral ribs that extend forward to meet and unite with the posterodorsal corner of the first primordial sacral centrum ( Fig. 6A, B View Figure 6 ). The sacral ribs on both sides are fractured, resulting in strong, subelliptical fractured surfaces ( Fig. 6A, B View Figure 6 ). The remnants of the transverse processes can also be observed ( Fig. 6C View Figure 6 ). Additionally, two fossae are visible on the dorsal surface of the centrum of the third sacral vertebra ( Fig. 6A, B View Figure 6 ), causing a constriction of the neural canal. The posterodorsal end of the centrum is sturdy and fused to the fourth sacral vertebra posteriorly ( Fig. 6A, B View Figure 6 ), which may indicate another set of sacral ribs.

The fourth sacral vertebra is severely fractured ( Fig. 6 View Figure 6 ). However, this particular centrum appears to be more robust than those of the other sacral vertebrae ( Fig. 6D View Figure 6 ; Supporting Information, Table S1). As mentioned earlier, the anterior end of the centrum is partially fused to the inserted primordial sacral vertebra. Two damaged surfaces at the anterodorsal corner exhibit morphological similarities to the sacral rib seen on the third sacral centrum ( Fig. 6A, B View Figure 6 ).

Pelvic girdle Ilium

Both ilia of LZ0895 are partially preserved ( Fig. 7 View Figure 7 ). Two fragments are tentatively identified as the right iliac blade with the sacral transverse processes and sacral ribs attached ( Fig. 7A–D View Figure 7 ). The dorsalmost portion of the blade is straight and horizontally oriented anteroposteriorly ( Fig. 7A, B View Figure 7 ). An elongate fossa is present along the lateral surface of the blade ( Fig. 7A, B View Figure 7 ), providing extensive space for thigh and tail musculature ( Hutchinson and Gatesy 2000, Schachner et al. 2011). Although portions of the sacral transverse processes are appressed to the medial surface of the iliac blade, it is uncertain whether they are coosified to each other ( Fig. 7C, D View Figure 7 ). The medial surface of the blade is predominantly flat, but displays several low ridges that approach the sacral vertebrae ( Fig. 7C, D View Figure 7 ).

The posteroventral part of the right preacetabular process is preserved ( Fig. 7E, G View Figure 7 ). The gap between the preacetabular process and the pubic peduncle is narrow, but wider than that in Dilophosaurus oetherilli ( Marsh and Rowe 2020) and Sarcosaurus ooodi ( Ezcurra et al. 2021) . The anterior half of the supraacetabular crest originates from nearly the distal end of the pubic peduncle and extends ventrolaterally over the dorsal margin of the acetabulum ( Fig. 7E, F View Figure 7 ), similar to that in other early neotheropods (e.g. Dilophosaurus oetherilli and Sarcosaurus ooodi ). In ventral view, the supraacetabular crest projects posterolaterally, with its posterior margin forming a steeper angle than the gradually rising anterior margin ( Fig. 7I View Figure 7 ).

The pubic and ischial peduncles form the superior part of an opened acetabulum ( Fig. 7E, F View Figure 7 ). Both peduncles extend laterally and slightly inward, forming the inner surface of the acetabulum ( Fig. 7E, F View Figure 7 ). The flat anterolateral surface of the ischial peduncle forms the dorsal half of the antitrochanter. The pubic peduncle is not coosified to the pubis, unlike Sarcosaurus ooodi ( Ezcurra et al. 2021) and some coelophysoids ( Raath 1977, Rowe and Gauthier 1990), which may represent skeletal immaturity. The articular surface of the pubic peduncle is only slightly kinked, as in Dilophosaurus oetherilli (TMM 43646-1), whereas it is strongly kinked in many coelophysoids ( Rauhut 2003). The articular surface of the pubic peduncle faces anteriorly like most non-averostran neotheropods and Ceratosauria (e.g. Elaphrosaurus bambergi : Rauhut and Carrano 2016), while that of Tetanurae faces ventrally (e.g. Allosaurus fagilis : Madsen 1976; Sinraptor dongi : Currie and Zhao 1993). The pubic peduncle is robust ( Fig. 8E, F View Figure 8 ), and more developed than in other neotheropods, such as Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Sarcosaurus ooodi (NHMUK PV R4840), and Liliensternus liliensterni ( von Huene 1934) , but not as robust as averostrans (e.g. Allosaurus fagilis : Madsen 1976; Majungasaurus crenatissimus : Carrano 2007; Piatnitzkysaurus floresi : Pradelli et al. 2025). The distal end of the pubic peduncle is slightly anteroposteriorly expanded with a subtriangular distal outline ( Fig. 7K View Figure 7 ). The ischial peduncle is obviously smaller than the pubic peduncle ( Fig. 7E, F View Figure 7 ). The distal surface of the ischial peduncle is subtriangular and its apex points laterally ( Fig. 7L View Figure 7 ). The posterior margin of the ischial peduncle is concave distally in lateral view (= posterior notch: Welles 1984); this notch is rounded and relatively large ( Fig. 7E–H View Figure 7 ), making the ischial peduncle more posteriorly projected and larger than in other non-averostran neotheropods, such as Dilophosaurus oetherilli ( Marsh and Rowe 2020) . Cryolophosaurus ellioti also has a long ischial peduncle, but its posterior margin is angled ( Smith et al. 2007: fig. 15A). This condition is similar to some averostrans (e.g., Sinraptor dongi : Currie and Zhao 1993; Majungasaurus crenatissimus : Carrano 2007; Piatnitzkysaurus floresi : Pradelli et al. 2025), but the ischial peduncle is not tapered as in averostrans in lateral view.

Pubis

Both the left and right pubes are damaged, yet we can describe their overall morphology ( Fig. 8 View Figure 8 ). The pubis is elongated, exceeding the length of the femur (Supporting Information, Table S1). The anteroproximal margin of the pubis is relatively straight ( Fig. 8B, D, H, J View Figure 8 ). The iliac peduncle is expanded into a subtriangular iliac articular surface that covers more than half the length of the proximal end of the pubis ( Fig. 7K View Figure 7 ). The ischial peduncle is flat and extends posteroventrally, contributing to the obturator process ( Fig. 8B, D, H, J View Figure 8 ). The iliac and ischial peduncles are closely positioned, separated only by a shallow concavity. The obturator process is thin and plate-like. On the right pubis, a broken, oblong obturator foramen is visible ( Fig. 8B View Figure 8 ). It is challenging to determine the presence of a second pubic fenestra located ventral to the obturator foramen, as observed in coelophysoids ( Camp 1936, Raath 1977, Carrano et al. 2005), due to inadequate preservation of this region of the pubis. Following Rauhut (2005), we suspect that there is insufficient area for the plate to support a pubic fenestra, similar to the situation seen in Cryolophosaurus ellioti ( Smith et al. 2007) .

A distinct ridge extends distolaterally on the anterior surface of the proximal pubis, curving slightly posteriorly to form an elongated, semicircular lateral tuber on the base of the shaft. Distal to this tuber, the shaft is a slender, straight rod with a teardrop cross-section, bending anteriorly around the proximal two-thirds of the pubis. These characteristics are similar to those of Liliensternus liliensterni and Dilophosaurus oetherilli ( Marsh and Rowe 2020) . The pubic aprons on both bones are broken and project posteromedially ( Fig. 8 View Figure 8 ). The apron originates from the anteromedial side of the shaft and ends approximately 6 cm above the distal end. Due to the damage, it is uncertain whether the aprons close distally.

The pubic boot is expanded anteroposteriorly and forms a triangle in distal view ( Fig. 8B, D, H, J View Figure 8 ). In lateral view, the pubic boot expands more posteriorly than anteriorly, a characteristic common among most theropods. Compared toother early neotheropods, such as Dilophosaurus oetherilli and Liliensternus liliensterni ( Tykoski 2005) , the pubic boot of LZ0895 is more posteriorly expanded, but not as developed as in most averostrans such as Allosaurus fagilis ( Madsen 1976) . However, the pubic boot of some averostrams such as Monolophosaurus jiangi ( Zhao and Currie 2010) is also not well developed.

Ischium

Three fragments are identified as part of the ischia, including the iliac and pubic peduncles of the right ischium and the pubic peduncle of the left ischium ( Fig. 9 View Figure 9 ). The iliac peduncle is longer anteroposteriorly than the pubic peduncle and appears reniform in proximal view ( Fig. 9E View Figure 9 ). The proximal surface of the iliac peduncle is divided into posterior and anterior surfaces by a low ridge ( Fig. 9A, E View Figure 9 ). The posterior surface, which articulates with the ilium, is much larger and concave, while the anterior surface constitutes the ventral half of the antitrochanter posterior to the acetabulum. In Dilophosaurus oetherilli , the anterior surface is similar in size to the posterior surface ( Marsh and Rowe 2020). Additionally, there is a smaller fragment that is identified as the left pubic peduncle. This peduncle is teardrop-shaped in proximal view and tapers anteroventrally into the obturator process ( Fig. 9F View Figure 9 ). A slender ridge is present on the dorsomedial surface of the pubic peduncle, which emerges from the base of the peduncle and sharply merges onto the proximal surface. This distinctive feature is not observed or documented in other early neotheropods, which possess a smooth medial surface of the pubic peduncle (e.g. Dilophosaurus oetherilli : Marsh and Rowe 2020). We, therefore, consider it an autapomorphy of LZ0895.

Hindlimb Femur

Both left and right femora are preserved, with the left being more complete than the right one, which is laterally compressed and deformed. However, the distal end of the left femur is also slightly damaged. Our description is based primarily on the left femur ( Fig. 10 View Figure 10 ). The femur is sigmoidal in both anterior and lateral views, characteristic of many early neotheropods ( Tykoski 1998, Smith et al. 2007, Marsh and Rowe 2020), but the curvature is stronger in lateral view ( Fig. 10 View Figure 10 ). The long axes of the proximal and distal ends are at an angle of 45°.

The femoral head is oriented anteromedially to articulate with the acetabulum. Three tubera are observed on the femoral head in proximal view: the anterolateral tuber, the anteromedial tuber, and the posteromedial tuber, with the anterolateral tuber being the most prominent ( Fig.10E, K View Figure 10 ), this is typical in early theropods.The anterolateral tuber is a broad surface forming the anterior corner of the femoral head, while the anteromedial tuber constitutes the medial corner. This tuber is separated by a smooth, longitudinal U-shaped sulcus from the posteromedial tuber ( Fig. 10E, K View Figure 10 ). The posteromedial tuber comprises much of the posterior margin of the femoral head in proximal view. On the proximal surface of the femoral head, there is a curved, posteromedial groove ( Fig. 10E, K View Figure 10 ) that resembles those of some early neotheropods ( von von Huene 1934, Smith et al. 2007, Nesbitt et al. 2009, Marsh and Rowe 2020), along with certain coelophysoids ( Raath 1977, Colbert 1989, Rowe 1989). However, other early neotheropods, or close relatives like Chindesaurus byansmalli ( Long and Murry 1995) and Pendraig milnerae ( Spiekman et al. 2021) , lack this feature. The groove could also indicate a skeletally immature individual ( Tsai and Holliday 2014, Griffin 2018). The dorsolateral trochanter is present on the lateral surface below the level of the most distal end of the anteromedial tuber ( Fig. 10B, H View Figure 10 ). The dorsolateral trochanter is an elongated ridge as in many early theropods, such as Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Liliensternus liliensterni ( von Huene 1934) , and Taoa hallae ( Nesbitt et al. 2009) , while it is a smooth area in averostrans ( Nesbitt 2011, Nesbitt and Ezcurra 2015).

On the proximal anterolateral surface of the femur, the anterior trochanter is subelliptical in both anterior and lateral views; it tapers distally to meet the femoral shaft and expands proximally, but is separated from the proximal end of the femur by a groove ( Fig. 10A, B, G, H View Figure 10 ). This condition resembles that of Dilophosaurus oetherilli ( Marsh and Rowe 2020) , and it is significantly different from the averostran wing-like anterior trochanter. The proximal end of the anterior trochanter is at the approximately distal third of the dorsolateral trochanter, extending past the ventral margin of the femoral head ( Fig. 10 View Figure 10 ). A trochanteric shelf is absent in this specimen, but there is a broadly sloping surface, resembling the condition in Dilophosaurus oetherilli ( Marsh and Rowe 2020) ; however, in the referred specimen of Dilophosaurus oetherilli (UCMP 77270), a well-developed trochanteric shelf is present ( Marsh and Rowe 2020). The development of a trochanteric shelf is interpreted as an ontogenetic character by Griffin (2018) and Marsh and Rowe (2020). A distinct mound projects laterally at the most distal level of the anterior trochanter on the posterolateral surface of the femoral shaft, below the dorsolateral trochanter ( Fig. 10A, C, G, I View Figure 10 ), interpreted as a posterolateral tuber in many theropods ( Rauhut 2003).

The fourth trochanter is a thin, sigmoidal ridge in posterior view, that is concave medially and convex laterally ( Fig. 10I View Figure 10 ), which is similar to the condition of Dilophosaurus oetherilli ( Marsh and Rowe 2020) and Cryolophosaurus ellioti ( Smith et al. 2007) and averostrans. Proximally, the fourth trochanter starts at a similar level as the posterolateral tuber and the distal end of the lesser trochanter. In lateral and medial views, the fourth trochanter is subtriangular, rising gradually, but decreasing a bit more abruptly ( Fig. 10H View Figure 10 ). The proximal end of the fourth trochanter is more robust than the distal end. On the anteromedial surface of the femur is a depression immediately medial to the fourth trochanter, probably representing an insertion for the M. caudofemoralis longus ( Carrano and Hutchinson 2002).

The femoral shaft is subelliptical in cross-section, with a posterolateral depression. The shaft is relatively slender and exhibits two longitudinal ridges, located beneath the anterior trochanter and posterolateral tuber, on the anteromedial and posterolateral surfaces, respectively ( Fig. 10G View Figure 10 ). A shallow triangular depression, the extensor fossa, separates the anterior margins of the distal medial and lateral condyles of the femur. The entepicondyle is weakly pronounced, and it is subtriangular in posterior view ( Fig. 10C, I View Figure 10 ).

The distal end of the femur consists of lateral and medial condyles, and the tibiofibular crest ( Fig. 10F, L View Figure 10 ). The popliteal fossa separates the lateral condyle and tibiofibular crest posteriorly from the medial condyle. In distal view, the flattened medial surface forms a right angle with its anterior surface, but it may be damage from manual preparation ( Fig. 10L View Figure 10 ). While the medial condyle projects slightly posteriorly, the combined lateral condyle and tibiofibular crest projects anterodistally ( Fig. 10H, J View Figure 10 ). In medial view, the medial condyle is boot-like and its proximal half extends to the femoral shaft ( Fig. 10J View Figure 10 ), unlike that in Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Cryolophosaurus ellioti ( Smith et al. 2007) , and averostrans. However, as we mentioned above, this unique morphology could be a result of manual preparation. The medial condyle and tibiofibular crest are subtriangular in distal outline ( Fig. 10L View Figure 10 ), which distinguishes them from Dilophosaurus oetherilli ( Marsh and Rowe 2020) . The distal outline of the lateral condyle is more rounded and swollen than that of the medial condyle ( Fig. 10L View Figure 10 ). The lateral condyle projects more anteriorly than the medial condyle, resembling Pooellvenator podocitus and Megapnosaurus rhodensiensis , contrasting the condition in the other neotheropods ( Ezcurra 2017). However, in anterior view, the lateral condyle of LZ0895 is projected distally much more than the medial condyle compared to other neotheropods ( Fig. 10L View Figure 10 ). We intend to interpret this feature as a result of preparation. A shallow groove on the lateral surfaces of the tibiofibular crest divides it from the lateral condyle; it starts along the lateral surface of the tibiofibular crest and terminates at the distal surface of the distal end ( Fig. 10H, I, L View Figure 10 ). This groove in Dilophosaurus oetherilli ( Marsh and Rowe 2020) extends down and around the lateral condyle, until almost reaching the anterolateral corner of the medial condyle. The tibiofibular crest of LZ0895 mainly projects posteriorly, which differs from the posterolateral projection seen in some other neotheropods including averostrans ( Ezcurra 2017). Additionally, like Dilophosaurus oetherilli ( Marsh and Rowe 2020) , LZ0895 does not possess the infrapopliteal ridge present in Ceratosaurus nasicornis ( Madsen and Welles 2000) , and coelophysoids ( Raath 1977, Colbert 1989, Rowe 1989).

Tibia

Only the right tibia is preserved ( Fig. 11 View Figure 11 ). It is slightly shorter than thefemur (SupportingInformation,TableS1) andisgentlybowed anteriorly, which is a common condition in early neotheropods. The proximal surface, the lateral condyle, and the anterior tip of the cnemial crest are damaged. A notch separates the medial and lateral condyles of the proximal end of the tibia posteriorly ( Fig. 11E View Figure 11 ). The lateral condyle is smaller than the medial one ( Fig. 11E View Figure 11 ). The proximal outline of the lateral condyle is more rounded, whereas the medial condyle is more subtriangular ( Fig. 11E View Figure 11 ). The medial condyle is more posteriorly projected than the lateral one; this resembles the condition of most neotheropods, except Tachiraptor ( Langer et al. 2014) . The proximal surface of the tibia extends slightly downwards towards the cnemial crest, but this could be damage from manual preparation. The medial condyle is smoothly confluent with the cnemial crest, but the lateral condyle and cnemial crest are separated laterally by two broad concavities ( Fig. 11E View Figure 11 ), although the posterior concavity could be a taphonomic artefact. The cnemial crest is well developed and laterally bowed, but its anterior corner is broken ( Fig. 11E View Figure 11 ). In this case, the cnemial crest could be anteroposteriorly as deep as, or deeper than, the posterior condyles of the proximal end of the bone, as in Pooellvenator podocitus ( Ezcurra 2017). The anterior margin of the cnemial crest is subcircular in proximal view and is subtriangular in lateral view, and it merges with the tibial shaft below the level of the proximal condyles ( Fig. 11B View Figure 11 ).

A long, straight fibular flange is evident on the lateral surface of the proximal end of the tibia ( Fig. 11B View Figure 11 ). The proximal end of the fibular flange is broken. However, it conspicuously reached the proximal surface of the tibia, as occurs in other non-tetanuran neotheropods ( Rauhut 2003). The shaft of the tibia is semicircular in cross-section. Two longitudinal ridges are present on the lateral and anterior surfaces of the tibia shaft ( Fig. 11A, B View Figure 11 ). The distal end of the tibia expands mediolaterally ( Fig. 11F View Figure 11 ). The distal outline of the tibia is subrectangular ( Fig. 11F View Figure 11 ), but is more anteroposteriorly compressed compared to other early neotheropods with the exception of Tachiraptor admirabilis ( Langer et al. 2014) . A longitudinal ridge is present on the lateral surface of the distal end of the tibia, resembling that found in Camposaurus arizonensis ( Ezcurra and Brusatte 2011) , Ceratosaurus nasicornis ( Madsen and Welles 2000) , and Dilophosaurus oetherilli ( Marsh and Rowe 2020) . A medial diagonal tuberosity ( Ezcurra and Brusatte 2011), which is found in some coelophysoids ( Ezcurra and Brusatte 2011, Ezcurra 2017), is absent in LZ0895. The anterolateral process ( Fig. 11A, F View Figure 11 ), also known as the facet for reception of the ascending process of the astragalus, is at an angle of 26° with respect to the horizontal plane, which is similar to the condition in other early non-averostran neotheropods, such as Cryolophosaurus ellioti ( Smith et al. 2007) , Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Sarcosaurus ooodi ( Ezcurra et al. 2021) , Tachiraptor admirabilis ( Langer et al. 2014) , and the early ceratosaurian Eoabelisaurus mefi ( Pol and Rauhut 2012) . This angle is lower in coelophysoids ( Ezcurra et al. 2021). The anterolateral process of LZ0895 is proximodistally more developed and anteroposteriorly more compressed than in coelophysoids, indicating a reception for a higher and thinner ascending process of the astragalus ( Fig. 11 View Figure 11 ). The posterolateral process of the tibia extends distally and posterolaterally, tapering posterolaterally in distal view ( Fig. 11F View Figure 11 ). The deep notch on the posteromedial corner of the distal surface of the tibia found in Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Cryolophosaurus ellioti ( Smith et al. 2007) , Sarcosaurus ooodi ( Ezcurra et al. 2021) , and Zupaysaurus rougieri ( Ezcurra and Novas 2007) is present but shallow in LZ0895 and Tachiraptor ( Fig. 11F View Figure 11 ).

Fibula

Both left and right fibulae are incompletely preserved ( Fig. 12 View Figure 12 ). The left one is missing its distal portion; the right one lacks some parts of shaft, and its proximal end is more severely damaged, but its distal end is relatively well preserved ( Fig. 12 View Figure 12 ). The fibula is long and slender ( Fig. 12 View Figure 12 ). In proximal view, the fibula is concave medially; the anterior end is rounder and thicker than the tapering posterior end, forming a comma-shape outline ( Fig. 12E, J View Figure 12 ), as occurs in some neotheropods like Dilophosaurus oetherilli ( Marsh and Rowe 2020) , ‘Syntarsus’ kayentakatae ( Rowe 1989) , and Sinraptor dongi ( Zhao and Currie 2010) . The proximal end of the fibula is sub-symmetrical in lateral view with the anterior margin straight, but the posterior margin concave ( Fig. 12B, G View Figure 12 ). The proximal end is the anteroposteriorly widest part of the fibula, with the shaft tapering distally until the distal end expands ( Fig. 12 View Figure 12 ). A large, well-developed fossa is present on the medial surface of the proximal portion of the bone, which receives the fibular flange of the tibia; it becomes gradually narrower and shallower distally, and ends approximately 9 cm above the distal margin ( Fig. 12C, I View Figure 12 ). This fossa morphologically resembles that in Dilophosaurus oetherilli ( Marsh and Rowe 2020) , a ridge present in coelophysoids and Ceratrosaurus ( Tykoski 2005) is absent in LZ0895. A short, low ridge for insertion of the M. iliofibularis extends along the anterolateral surface of the proximal portion of shaft ( Fig. 12B View Figure 12 ). The shaft exhibits a crescent-shaped cross-section distal to the ridge, with a convex lateral surface and a medial surface featuring a shallow longitudinal groove ( Fig. 12C View Figure 12 ).

Astraight,lowridgestartswheretheshaftisslenderest, forming the anterior margin of the distal end ( Fig. 12 View Figure 12 ). The distal end is sub-symmetrical in lateral view and is anteroposteriorly shorter than the proximal end ( Fig. 12G View Figure 12 ; Supporting Information, Table S1). In distal view, the distal end is subtriangular ( Fig. 12K View Figure 12 ). The distal end of the bone widens towards its distal portion, creating a sloping surface at the anterodistal end and potentially making contact with the ascending process of the astragalus. A tubercle sits anteromedially at the distal end ( Fig. 12H, I View Figure 12 ). This feature is not present in other neotheropods, such as Cryolophosaurus ellioti ( Smith et al. 2007) , Dilophosaurus oetherilli ( Marsh and Rowe 2020) , and Zupaysaurus rougieri ( Arcucci and Coria 2003) . In Sinraptor dongi there is a similar structure ( Currie and Zhao 1993). However, this tubercle does not extend proximally as in Sinraptor dongi , and it seems unusual in theropods. Thus, we intend to interpret it as a remnant of the ascending process of astragalus stuck to the distal end of the fibula.

Metatarsus

Metatarsal I is considerably short (Supporting Information, Table S1), with only the distal portion preserved ( Fig. 13B–E View Figure 13 ). Two rugosities are present at the distal end of the shaft, with one on the distolateral surface and the other on the ventromedial surface. The distal condyles are separated ventrally by a groove, and transition into a smooth, bulbous, dorsally projecting distal articular surface ( Fig. 13A View Figure 13 ). The distal articular surface is asymmetrical in distal view ( Fig. 13A View Figure 13 ). Ligament fossae are evident on the lateral and medial surfaces of the distal end, and the lateral fossa is smaller than the medial fossa ( Fig. 13C, E View Figure 13 ). Additionally, a tuberosity is present on the ventrolateral margin of both lateral and medial ligament fossae ( Fig. 13D View Figure 13 ).

Metatarsal II is long and nearly complete, with the medial half of the proximal end crushed so that it is slightly oblique to the shaft. It is nearly trapezoidal in proximal view. ( Fig. 13F–I View Figure 13 ). The longer base of this trapezoid occurs on the lateral side, and the trapezoid is dorsoventrally elongate. The medial surface of the proximal half articulating with metatarsal III is flat.The remaining shaft is relatively round and tapers slightly distally ( Fig. 13G View Figure 13 ). An extensor fossa is absent on the anterior surface of the distal end, similar to Dilophosaurus oetherilli ( Marsh and Rowe 2020) , Dracoraptor hanigani ( Martill et al. 2016) , and Sarcosaurus ooodi ( Ezcurra et al. 2021) , but is present in Allosaurus fagilis ( Madsen 1976) . The distal surface is smooth and rounded. The distal condyles are separated ventrally, and the lateral condyle is significantly larger than the medial condyle. The lateral ligament fossa is much larger and deeper than the medial ligament fossa ( Fig. 13G, I View Figure 13 ). Metatarsal II is asymmetrical in distal view; the lateral margin is distinctly concave, while the medial margin is convex ( Fig. 13A View Figure 13 ). The size of the distal end of metatarsal II is subequal to that of metatarsal III (Supporting Information, Table S1), which is significantly smaller in Dilophosaurus oetherilli ( Marsh and Rowe 2020) .

Only the distal half of metatarsal III is preserved ( Fig. 11J– M View Figure 11 ). The distal half of the shaft is subelliptical in cross-section. The dorsal surface of the shaft is relatively flat and smooth ( Fig. 13J View Figure 13 ). Metatarsal III is bowed medially ( Fig. 13J View Figure 13 ). The distal end is expanded medially ( Fig. 13J, L View Figure 13 ). The medial condyle is slightly taller than the lateral condyle in distal view ( Fig. 13A View Figure 13 ). These condyles are separated ventrally by a shallow groove ( Fig. 13A View Figure 13 ), like Dilophosaurus oetherilli ( Marsh and Rowe 2020) , but unlike Allosaurus fagilis ( Madsen 1976) . The lateral and medial ligament fossae are subequal in size and outline ( Fig. 13K, M View Figure 13 ).

Pedal phalanges

Digit I: Only the proximal half of phalanx I-1 is preserved; it is long and subcylindrical ( Fig. 14A–D View Figure 14 ). Its proximal surface is concave and rounded. A ridge arises from the dorsal margin of the distal end extending to the shaft. The shaft is elliptical in cross-section.

Digit II: Right phalanx II-1 and left phalanx II-2 are preserved ( Fig. 14E–L View Figure 14 ). Phalanx II-1 is robust ( Fig. 14E–H View Figure 14 ). The proximal articular surface of phalanx II-1 is concave. In proximal view, the dorsal margin is rounded, but the ventral edge is concave. Proximolaterally, a distinct low ridge is present on the bone surface, rising from the proximolateral margin, and then merging into the shaft at around midpoint ( Fig. 14E, G View Figure 14 ). The lateral and medial condyles are subequal in height, and they are separated by a shallow concavity on the distal surface. A shallow extensor pit is present on the dorsal surface ( Fig. 14E View Figure 14 ). Phalanx II-2 is similar to II- 1 in general morphology, but smaller in size ( Fig. 14I–L View Figure 14 ). Its proximal end is divided into lateral and medial articular surfaces by a low ridge that extends to a laterally inclined tubercle. On the proximal half, a low ridge is seen on the ventrolateral surface ( Fig. 14J, L View Figure 14 ). The distal condyles are separate and sub-symmetrical ( Fig. 14I View Figure 14 ). The lateral condyle is slightly taller than the medial condyle.

Digit III: Only the distal end of left phalanx III-1 is preserved ( Fig. 14M–P View Figure 14 ). A shallow, elliptical extensor pit is present on the dorsal surface at the distal end. In distal view, the medial margin is relatively straight, but the lateral margin is inclined ventromedially. The distal condyles are divided by a slight ventral concavity ( Fig. 14M, O View Figure 14 ). Oblong ligament fossae are present on the side of both distal condyles; the lateral one is obviously larger than the medial one ( Fig. 14N, P View Figure 14 ).

Digit IV: Left phalanx IV-1 and the proximal end of left phalanges IV-2 and 3 are present ( Fig. 14Q View Figure 14 –AB). Phalanx IV-1 is not as elongated as the phalanges of digits II and III ( Fig. 14Q–T View Figure 14 ). Phalanx IV-1 is sub-triangular in proximal view, with a peak inclinded laterally. The shaft is short and does not taper appreciably. The distal condyles are separated by a relatively deep concavity, and the lateral condyle is distinctly taller than the medial condyle ( Fig. 14Q, S View Figure 14 ). A deep, circular extensor pit is present on the distal dorsal surface ( Fig. 14Q View Figure 14 ). The medial and lateral ligament fossae are wide, and the lateral one is much deeper ( Fig. 14R, T View Figure 14 ). Phalanges IV-2 and 3 are relatively slender with strongly concave proximal articular surfaces ( Fig. 14U View Figure 14 –AB).

Metatarsal III histology

The thin section of metatarsal III of LZ0895 was strongly influenced by taphonomic alteration petrogenesis, and some parts of the bone surface were slightly mechanically damaged during preparation ( Fig. 15A View Figure 15 ). The section displays that the cortex mainly consists of fibrolamellar bone with dense primary vascular canals ( Fig. 15B, C View Figure 15 ), and we do not observe a trend of reduction of fibrolamellar bone towards the external margin of the epiphysis. Fibrolamellar bone is typical of early and most active stages of skeletal growth in medium-sized and large endothermic tetrapods ( de Buffrénil and Quilhac 2021). The medullary cavity is subelliptical and filled with quartz and calcite crystals, and these crystals expand outwards to cover the border between the medullary cavity and cortex ( Fig. 15B, C View Figure 15 ). Five annuli can be identified ( Fig. 15B View Figure 15 ), representing temporary decreases in growth, but no LAGs (lines of arrest growth) are clearly visible. These growth marks are often localized and not continuously traceable around the entire circumference of the bone. Although fibrolamellar bone occupies most of the cross-section, a relatively thinner part of the section is dominated by lamellar bone ( Fig. 15B, C View Figure 15 ). No Sharpey’s fibres are observed in the section. The section presents a transition from longitudinal to reticular primary vascular canals from the internal to external cortex ( Fig. 15B, C View Figure 15 ). A few vascular canals connect to the bone surface ( Fig. 15B, C View Figure 15 ). The vascular density is remarkably high in the whole cortex ( Fig. 15B, C View Figure 15 ), indicating that LZ0895 may have died during a rapid-growth stage. Primary osteons are randomly distributed in the cortex, and secondary osteons are sparse ( Fig. 15B, C View Figure 15 ).

Phylogeny

Equal-weights parsimony

The analysis recovered 112 most-parsimonious trees (MPTs), each of which had a length of 1402 steps, a consistency index (CI) of 0.340, and a retention index (RI) of 0.690. The strict consensus tree (SCT) generated from all MPTs places LZ0895 as the sister-taxon to Averostra ( Fig. 16 View Figure 16 ). LZ0895 nests in a grade leading to Averostra (averostran-line theropods) that includes large non-averostran neotheropods such as Cryolophosaurus ellioti and Dilophosaurus oetherilli , which together with Coelophysoidea and Averostra, make up Neotheropoda. However, in this clade, Sarcosaurus ooodi , Gojirasaurus quayi , and Cryolophosaurus ellioti form a polytomy ( Fig. 16 View Figure 16 ). Dilophosaurus oetherilli , Shuangbaisaurus anlongbaoensis , and Sinosaurus triassicus are supported as a distinctive subclade, within which Shuangbaisaurus anlongbaoensis and Sinosaurus triassicus are sister-taxons to each other ( Fig. 16 View Figure 16 ).

Eodromaeus murphi is recovered as the sister-taxon to Neotheropoda ( Fig. 16 View Figure 16 ). Dracoraptor hanigani is found at the base of Coelophysoidea, together with Liliensternus liliensterni , but the other taxa in Coelphysoidea form a polytomy ( Fig. 18B View Figure 18 ). Chindesaurus bryansmalli and Taoa hallae are non-herrerasaurid herrerasaurians, and herrerasaurids are recovered as early members of Theropoda ( Fig. 16 View Figure 16 ).

The Bremer support is 1 for the node Neotheropoda, and for all less inclusive clades nested within it, except for Tetanurae and Ceratosauria ( Fig. 16 View Figure 16 ). The GC bootstrap frequency for the Shuangbaisaurus anlongbaoensis + Sinosaurus triassicus clade is quite low, at 13%. The absolute frequency of Neotheropoda is relatively high, 53% ( Fig. 16 View Figure 16 ). GC frequency is only 12% for the lineage leading to Averostra. The absolute frequency for LZ0895 + Averostra is 50%. Tetanurae is the best supported in both absolute and GC bootstrap frequencies within Neotheropoda, at 89% and 93%, respectively ( Fig. 16 View Figure 16 ). The iter PCR analysis identified three topologically unstable terminals: Lucianvenator bonoi, Sarcosaurus ooodi , and Pendraig minerae . The pruning of these terminals increases Bremer's support for the Averostra, as well as the resolution within the Coelophysoidea and the base of the averostran-line neotheropods (Supporting Information, Fig S1 View Figure ).

Extended implied-weights parsimony

The analysis with K = 7 (fit of 86.36960, CI of 0.342 and RI of 0.705) found 3 most parsimonious trees, and the analyses with K = 8–11 only found one MPT each (K = 8: fit of 78.78407, CI of 0.340 and RI of 0.689; K = 9: fit of 72.44163, CI of 0.340 and RI of 0.689; K = 10: fit of 67.06415, CI of 0.340 and RI of 0.689; K = 11: fit of 62044359, CI of 0.340 and RI of 0.689). The MPTs from the analyses with K = 8–11 are very well resolved, and they share the same topology (Supporting Information, Figs S3–S View Figure 3 5 View Figure 5 ). Conversely, the strict consensus tree derived from three MPTs of the analysis with K = 7 is not well resolved (Supporting Information, Fig S2 View Figure 2 ). Within the MPTs from the analyses with K = 8–11, the K = 11 analysis is associated with the best absolute and GC frequencies. Therefore, the MPT from analysis with K = 11 is considered to be the most representative result. The topology of the most parsimonious tree of the analysis with K = 11 is overall very similar to the one recovered in the strict consensus tree of the equal-weights analysis above, but it failed to recover Ceratosauria ( Fig. 17 View Figure 17 ). LZ0895 is once again recovered as the sister-taxon to Averostra, but in this tree, the relationships of other near-averostrans are better resolved than in the equal-weights strict consensus. Surprisingly, Shuangbaisaurus anlongbaoensis and Sinosaurus triassicus once again form a sister-taxon pair, with the absolute bootstrap frequency (51%) is much higher than the GC frequnency (19%) ( Fig. 17 View Figure 17 ). Furthermore, Cryolophosaurus ellioti , Dilophosaurus oetherilli , Shuangbaisaurus anlongbaoensis , and Sinosaurus triassicus are supported as a monophyletic clade, but with a quite low GC frequnency (13%). The absolute and GC frequencies are low for Neotheropoda, at 72% and 64%, respectively ( Fig. 17 View Figure 17 ). The GC frequency for the lineage leading to Averostra is extremely low (25%). The absolute and GC frequencies for LZ0895 + Averostra are 70% and 63%, respectively ( Fig. 17 View Figure 17 ). Tetanurae are the best supported in both absolute and GC bootstrap frequencies within Neotheropoda, 90% and 89% ( Fig. 17 View Figure 17 ), respectively.