Kryphioparma caerula Reyes, Parker & Heckert, 2023, SP. NOV.
Creators: name: Reyes, William A.
name: Parker, William G.
name: Heckert, Andrew B.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Aetosauria
Stagonolepididae
Kryphioparma
Kryphioparma caerula

description: KRYPHIOPARMA CAERULA SP. NOV.   
FIGS. 2–4  
 Zoobank LSID — urn:lsid:zoobank.org:act: DD0FED1D-C878-47DE-AC90-F5897B8305C9.   
 Diagnosis —Same as for genus.   
 Etymology — caerula, Latin for “cearulus”, meaning blue, after the Blue Mesa Member of the Chinle Formation. The stratigraphic member in which the type specimens were collected from.   
 Holotype — UCMP 165173 (Fig. 2A‒F), incomplete right paramedian osteoderm.   
 Paratype — UCMP 126847 (Fig. 2G‒L), medial fragment of left paramedian osteoderm.   
 Referred specimens — PEFO 51662 (Fig. 2M‒R) and PEFO 46468 (Fig. 2S‒X) fragmentary paramedian osteoderms.   
 Type locality — UCMP A269, Placerias Quarry (Camp and Welles 1956; Fig. 1).   
 Referred locality —PFV 456, Thunderstorm Ridge locality (Kligman et al. 2023; Fig. 1).   
 Age —Late Triassic, early-mid Norian, U-Pb detrital zircon maximum depositional age constraint ~223-218 Ma for the upper Blue Mesa Member, Chinle Formation (Ramezani et al. 2014, Rasmussen et al. 2020; Fig. 1); Adamanian estimated holochronozone (Martz and Parker 2017).   
 Stratigraphic Occurrence —Chinle Formation, upper Blue Mesa Member (Martz et al. 2012, Ramezani et al. 2014, Kligman et al. 2023; Fig. 1).   
 Description and remarks —The osteoderm fragments presented here for Kryphioparma caerula sp. nov. (Fig. 2) lack the flexure associated with lateral osteoderms (Parker 2007, 2016a). They are also not reminiscent of ventral osteoderms because they are not square-shaped like those observed in the trunk region of Coahomasuchus chathamensis Heckert et al. (2017) and Typothorax coccinarum Cope (1875) (Martz 2002, Heckert et al. 2010) nor are they elongate and flexed like those observed in the caudal region of Coahomasuchus kahleorum Heckert and Lucas (1999) and Calyptosuchus wellesi Case (1932) (Long and Ballew 1985, Long and Murry 1995). Thus, their quadrangular appearance indicates that they are fragments of dorsal paramedian osteoderms (Fig. 2B, C, H, I, N, O, T, U).   
 Because of the relatively complete preservation of the dorsal carapace for various aetosaurian taxa including Co. chathamensis, Co. kahleorum, Ty. coccinarum, Desmatosuchus spurensis, Desmatosuchus smalli, Ca. wellesi, Aetosauroides scagliai Casamiquela (1960), Aetosaurus ferratus, and Paratypothorax andressorum Long and Ballew (1985), we can deduce the regional position (i.e., cervical, trunk, sacral, caudal) from which these paramedian fragments are most likely derived (following discussion in Parker 2007, Parker and Martz 2010). The general morphology of the osteoderm fragments of Kr. caerula indicate that the paramedian osteoderms were flat and rectangular. Thus, they lack the dorsal anterolateral curvature characteristic of paramedian osteoderms from the cervical and anterior-most trunk region (Parker 2007) seen in other typothoracines, differing from the un-curved anterior paramedians of Co. kahleorum (NMMNH P-18496, Heckert and Lucas 1999) and Aetosaurus ferratus (SMNS 5770, Schoch 2007). The fragments lack evidence of mediolateral flexure (Fig. 2D, J, P, V), such flexure is a characteristic morphology of paramedian osteoderms from the cervical and most of the caudal region in aetosaurs (e.g., Ca. wellesi, UMMP 13950, Parker 2018), so we can reject their referral to these regions of the dorsal carapace. We hypothesize that the paramedian osteoderm fragments of Kr. caerula are most likely derived from the trunk region due to the large portion of the carapace the trunk composes; alternatively, these fragments may also be derived from the sacral and / or anterior-most caudal regions. The dorsal paramedian osteoderms across these regions are subject to morphological variation in their flexure, orientation of the dorsal process, presence of beveling along the posterior edge, and development of the dorsal eminence; that variation is best observed in aetosaurs that preserve a well-articulated carapace such as Ty. coccinarum (NMMNH P-56299, Martz 2002, Heckert et al. 2010), Ca. wellesi (Case 1932, Long and Ballew 1985, Parker 2018), and Co. kahleorum (Heckert and Lucas 1999). Some features stay consistent, most notably the dorsal ornamentation (Parker 2016a, Reyes personal observation). However, recent studies focused on the intraspecific variation of paramedian osteoderms indicate that the dorsal ornamentation can vary in its complexity (i.e., radial, anastomosing, random) between the various regions of the carapace within some taxa (e.g., Ae. scagliai, Taborda et al. 2015; Co. chathamensis, Hoffman et al. 2019) and is likely related to ontogeny and / or sexual dimorphism; this area of research is incipient and requires further sampling across the clade to determine the extent of intraspecific variation within the aetosaurian carapace. With this in mind, we compare the dorsal paramedian osteoderms of Kr. caerula with homologous osteoderms of other aetosaurs documented from the Late Triassic strata in the southwestern US (e.g., Long and Murry 1995, Heckert and Lucas 1999, 2000, Parker 2007, 2008, 2016a; Parker et al. 2008; Parker and Martz, 2010); this includes De. spurensis (Fig. 3B), De. smalli (Fig. 3B), Ca. wellesi (Fig. 3C), Paratypothorax sp. (Fig. 4J), Ty. coccinarum (Fig. 4N), Te. chatterjeei Martz and Small (2006) (Fig. 4C–J), Scutarx deltatylus Parker (2016b), Sierritasuchus macalpini (Parker et al. 2008) and Adamanasuchus eisenhardtae Lucas et al. (2007).   
 Although our morphological understanding of Kr. caerula is limited to a few osteoderm fragments (Fig. 2), those fragments provide sufficient morphological information to differentiate them from those of other aetosaurs, including all other known Adamanian taxa. The dorsal ornamentation of the paramedian osteoderms of Kr. caerula is composed of large, randomly oriented, well-incised oblong pits (Fig. 2B, H, N, T). The density of those pits relative to the available dorsal surface area is low approximately 20 pits per 5 cm transverse width; the opposite condition is observed in Ty. coccinarum (Long and Murry 1995, Martz 2002; Fig. 4N) where pits are also randomly oriented but have a higher concentration relative to available surface area. The dorsal ornamentation in Kr. caerula (Fig. 3A) is unlike the ornamentation composed of pits and grooves radiating from the center of ossification observed in Ca. wellesi (Long and Ballew 1985, Parker 2018; Fig. 3C), Ad. eisenhardtae (PEFO 34638, Lucas et al. 2007), Co. kahleorum (Heckert and Lucas 1999), Sc. deltatylus (PEFO 34045, Parker 2016b), or Rioarribasuchus chamaensis Zeigler et al. (2003). These osteoderms instead exhibit the anastomosing to intermediate ornamentation pattern as defined by Taborda et al. (2015). Anteriorly, the osteoderms of Kr. caerula exhibit a well-developed anterior bar on the dorsal surface (Fig. 3A), a condition shared with most aetosaurs except De. smalli and De. spurensis, which exhibit a depressed lamina (Long and Ballew 1985, MNA V9300, Parker 2008; Fig. 3B). These features differentiate Kr. caerula from Desmatosuchus and Ca. wellesi, which are also documented in the Placerias Quarry (Camp and Welles 1956, Parker 2018; Fig. 3) and Thunderstorm Ridge locality.   
 We interpret UCMP 165173 as representing the lateral portion of a fragmentary trunk paramedian osteoderm. This fragment indicates that the paramedian osteoderms of Kr. caerula exhibit an apparent high width-to-length ratio, being much transversely wider than anteroposteriorly long (Fig. 4A); a condition shared with the typothoracines (Parker 2007; Fig. 4), Ty. coccinarum (Martz 2002, Heckert et al. 2010; Fig. 4N), Ri. chamaensis (NMMNH P-33820, Zeigler et al. 2003, Parker 2007), Paratypothorax sp. (PEFO 3004, Hunt and Lucas 1992, Long and Murry 1995, Martz et al. 2013; Fig. 4K), and Te. chatterjeei (TTU-P 545, Martz and Small 2006; Fig. 4C, 4J). This differs strongly from stagonolepidoids such as Ca. wellesi (Long and Ballew 1985), De. spurensis (Parker 2008), and Si. macalpini (UMMP V60817, Parker et al. 2008). Like typothoracines, Kr. caerula also exhibits a well-developed ventral strut on the ventral surface (Figs. 2F, L, O, W-X; 4H), where the strut thickens in the direction of the center of ossification. That differs from the condition observed in Ca. wellesi (Parker 2018), Ad. eisenhardtae (Lucas et al. 2007), and Sc. deltatylus (Parker 2016b) which exhibit a weakly developed ventral strut, or Desmatosuchus (Parker 2008) and Si. macalpini (Parker et al. 2008), which lack it completely. Thus, these morphological features of Kr. caerula align with typothoracines (Martz 2002, Martz and Small 2006, Parker 2016a; Fig. 4), but as noted above the dorsal ornamentation of Kr. caerula does not align with that observed in Ty. coccinarum (Fig. 4N). A notable feature of the fragmentary paramedian osteoderms of Kr. caerula is that the posterior margin is dorsoventrally thickened like the condition observed in Te. chatterjeei (Martz and Small 2006, Heckert et al. 2007; Figs. 2D, J, P, V, 4F), but unlike the condition exhibited by Paratypothorax sp. (PEFO 3004) in which the paramedian osteoderms are thinner in comparison (Reyes personal observation).   
 Unlike the condition observed in Te. chatterjeei (Fig. 4G, I) and Paratypothorax sp. (Fig. 4J), the osteoderms of Kr. caerula do not exhibit a beveled posterior margin (Parker 2016a; Fig. 4A). However, this morphological feature is not consistent across the dorsal carapace as exemplified by Paratypothorax sp. (Hunt and Lucas 1992) and Te. chatterjeei (Martz and Small 2006, Heckert et al. 2007; Fig. 4F, H, J). Beveling along the posterior margin of the paramedian osteoderms is absent in the caudal region of Paratypothorax sp. (PEFO 3004, Lucas et al. 2006) and not fully exposed in dorsal view in the anterior trunk region of Te. chatterjeei (UMMP 9600, TTU-P 545, Martz and Small 2006, Heckert et al. 2007; Fig. 4C, F). However, the dorsal ornamentation in those paramedian osteoderms is clearly different from that of Kr. caerula (Fig. 4A); Te. chatterjeei exhibits small,spaced-out circular pits with long grooves near the posterolateral dorsal surface (Martz and Small 2006; Fig. 4J), while in Paratypothorax sp. dorsolateral surface is dominated by long parallel grooves (Lucas et al. 2006; Fig. 4K).   
 One paramedian osteoderm fragment of Kr. caerula (UCMP 126847) (Fig. 2G‒L) preserves an anteroposteriorly straight medial edge indicating that it is from the left side. This medial edge lacks the strong articulation composed of interlocking grooves and ridges (Fig. 2K) that are observed in Desmatosuchus (Case 1922, Long and Ballew 1985, Parker 2007, 2008). Lastly, the paramedian osteoderms of Kr. caerula exhibit inclined grooves on their posterior margin (Fig. 2D, J, N, T, V). These grooves have also been documented in paratypothoracin taxa (Fig. 4F, J, K), where they incline towards the dorsal eminence / center of ossification (Martz and Small 2006, Reyes personal observation); this appears to also be case Kr. caerula (Fig. 2) where the grooves on the posterior margin incline towards the center of ossification. Unfortunately, due to the fragmentary nature of the preserved paramedian osteoderms of Kr. caerula, we are unable to confirm the presence of a dorsal eminence.
description: Published as part of Reyes, William A., Parker, William G. & Heckert, Andrew B., 2023, A new aetosaur (Archosauria: Pseudosuchia) from the upper Blue Mesa Member (Adamanian: Early-Mid Norian) of the Late Triassic Chinle Formation, northern Arizona, USA, and a review of the paratypothoracin Tecovasuchus across the southwestern USA, pp. 1-15 in PaleoBios 40 (9) on pages 4-9, DOI: 10.5070/P940961559, http://zenodo.org/record/10913615