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Holotypic partial right ilium of Astrophocaudia slaughteri (SMU 61732) in: A, dorsal; and B, lateral views. Dashed lines indicate missing bone. Scale bar = 10 cm.
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Early Cretaceous sauropods were among the first dinosaurs discovered in North America, but several aspects of their taxonomy and evolution remain poorly understood. Much of this ambiguity stems from lack of anatomical overlap among taxa and the 125-year-long taxonomic confusion surrounding the sauropods Astrodon and Pleurocoelus. New discoveries ha...
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... total of about 20 fragmentary dorsal ribs are present; none are ‘plank-like’ (cross section more than three times wider than broad). Some of the preserved ribs approach this condition (cross sectional ratio 2.8), so Astrophocaudia may have plank-like ribs as do titanosauriforms (Wilson 2002). The largest dorsal rib is pneumatic as in Titanosauriformes ( Fig. 8). There is an oval, ridged tubercle on the anterior half of the proximolateral part of the largest dorsal rib (Fig. 8A). This feature is absent in the only other dorsal rib that preserves this portion of the shaft. Langston (1974) reported a single chevron with SMU 61732. In the process of studying the material, a second was discovered. Both come from the anterior region of the tail. The more complete chevron is missing only its distal- most blade (Fig. 9). It is 24.2 cm long and has an open hemal canal measuring 9.1 cm deep dorsoventrally. On the anterior face of the blade, there is a flattened oval boss measuring 1.2 × 4 cm that has a texture of ridges and grooves (Fig. 9). Each arm of the chevron bears a single articular facet with a medially pointed process. A distal scapular blade (Fig. 10) is preserved, which will be described as if held subvertically. The blade has complete anterodorsal and posteroventral margins, and is almost complete distally. It could represent a left or right scapula, as the preserved part is symmetrical about its long axis. The preserved length is 70 cm. Its breadth ranges from 17 to 38.5 cm, giving a minimum/maximum width ratio of about 2.3. The scapular blade is less than 1 cm thick distally and about 3 cm thick at the centre of the broken base of the blade. The base of the blade is flat in cross section as in Euhelopus and titanosaurs, rather than D-shaped with a broad lateral ridge as in non-somphospondylans (Wilson & Sereno 1998). The bone has a texture of subtle, axially oriented ridges and grooves on the exterior face of the bone. The acetabular region and part of the preacetabular process of the right ilium are present (Fig. 11). The preacetabular lobe of the ilium flares outward at about 45 ◦ along a gentle curve, as in most titanosauriforms (Salgado et al. 1997). No evidence of pneumaticity exists in the preserved ilium. A subtle ridge extends anteroposteriorly above the pubic peduncle on the lateral face of the ilium, as in some other sauropods (e.g. Camarasaurus ; Ostrom & McIntosh 1966). This ridge helps to delimit a subtle subtriangular fossa just above and in front of the public peduncle, as in some other sauropods (e.g. Cetiosaurus ; Upchurch & Martin 2003). The ventral edge of the preacetabular process is crushed inwards. The total preserved length of the element is 45 ...
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There are five taxa of tribosphenic mammals in the Early Cretaceous Antlers Formation of Texas and Oklahoma, USA: a basal stem therian (Kermackia texana), stem therians near the eutherian-metatherian dichotomy (Holoclemensia texana and Pappotherium pattersoni), and stem marsupials (Atokatheridium boreni and Oklatheridium szalayi). K. texana has a p...
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... Whereas pneumatic fossae and foramina are pervasive in the presacral vertebrae of eusauropods, and common in the sacral and caudal vertebrae of neosauropods (e.g., Euhelopus, Brachiosaurus;Wedel, 2003aWedel, , 2005Wedel and Taylor, 2013;Wilson et al., 2011), pneumatic dorsal ribs are much less common among sauropods, and to date have only been found in the mamenchisaurid Xinjiangtitan (Zhang et al., 2022) and some members of Neosauropoda. Pneumatic dorsal ribs are apomorphic for the macronarian clade Titanosauriformes (Wedel, 2005;Wilson & Sereno, 1998;Woodward & Lehman, 2009) with pneumatic ribs present among brachiosaurids (Carpenter & Tidwell, 2005;Janensch, 1950;Riggs, 1904;Tidwell & Wilhite, 2005), early diverging somphospondyls (Canudo et al., 2008;Carballido et al., 2011;Poropat et al., 2016;Rose, 2007;Taylor et al., 2011;Wilson & Sereno, 1998), and many other basally branching and derived titanosaurs (Cerda et al., 2012;D'Emic, 2013;Díez Díaz et al., 2013;Filippi et al., 2011;Gomani, 2005;González-Riga & David, 2014;Gorscak et al., 2014Gorscak et al., , 2017Gorscak & O'Connor, 2019;Hocknull et al., 2009;Lacovara et al., 2014;Malkani, 2003;Woodward & Lehman, 2009). Other groups of neosauropods, such as rebbachisaurids and early diplodocids, have apneumatic dorsal ribs (Fernández-Baldor et al., 2011;Wedel, 2005). ...
... This supports a degree of variability of pneumatic features in titanosauriforms as we propose for diplodocids. A similar pair of fossae separated by a bony ridge are present in a dorsal rib of Astrophocaudia (D'Emic, 2013), although the repeating fossae in MWC 9617 are located more distally along the rib. All of these examples are consistent with the description of subfossae, or fossae-within-fossae, as defined by Wilson (1999). ...
Postcranial pneumaticity is interpreted as a weight saving adaptation in sauropod dinosaurs, especially in the vertebral column. In some derived sauropods pneumatic features also occur on vertebral ribs. While pneumatic ribs are considered diagnostic of the clade Titanosauriformes, they are also infrequently found in diplodocid sauropods. Here, we describe a partial dorsal rib IV or V referable to Apatosaurus sp. that exhibits a series of superficial pneumatic fossae along its posterior surface. These fossae differ from the morphology found in other pneumatic dorsal ribs of diplodocids, including other apatosaurines and Supersaurus. Moreover, the pneumatic features of this rib are more distally located from the capitulum and tuberculum than in other diplodocids and titanosaurs. Based on our findings, we propose that rib pneumaticity among apatosaurine sauropods (and potentially all diplodocids) is individually variable, in addition to being a function of ontogeny. More broadly, we conclude that rib pneumaticity among diplodocids is morphologically variable when present and individually expressed rather than being ubiquitous throughout the clade. Our findings are consistent with the hypothesis that pneumatic ribs evolved independently between Diplodocidae and Titanosauriformes and make for poor clade-level characters among diplodocids.
... Astrodon johnstoni Leidy, 1865 is a sauropod dinosaur from the Early Cretaceous Arundel Formation of Maryland, eastern United States. The holotype (YPM VP 798) consists of one complete tooth and a section of a second tooth, deposited in Yale University's Peabody Museum of Natural History (New Haven, Connecticut, United States) (Leidy, 1865;D'Emic, 2013). The genus Astrodon has a long and convoluted taxonomic history, having at times been synonymized with Pleurocoelus Marsh, 1888 (see D'Emic, 2013 for history). ...
... Carpenter & Tidwell (2005) diagnosed Astrodon johnstoni based on various skeletal features, none of which were related to the teeth, and therefore none of which were present in the holotype. Though Astrodon johnstoni has been regarded as a nomen dubium in the last decade (D'Emic, 2013), it remains a historically and culturally significant taxon as one of the first dinosaurs discovered in the Americas, and it was designated as the State Dinosaur of Maryland (Maryland Code, General Provision § 7-322). Additionally, its holotype remains the first specimen indicating that sauropod dinosaurs were present in this region during the Early Cretaceous, and the first sauropod discovered in the Americas. ...
... Though the authorship of the name Astrodon is correctly cited as Leidy, 1865 by Neave (1939) and in the online data repository IRMNG (2021a, b) and others that compile IRMNG data, various scientific publications after 1939 regarding the genus have misattributed its authorship to Johnston (e.g., Ostrom, 1970;Galton, 1981;Kranz, 1989;D'Emic, 2013). Carpenter & Tidwell (2005) confusingly stated that "the genus was proposed in 1859 by Christopher Johnston" and also that "Leidy is considered the author." ...
The authorship of the sauropod dinosaur genus Astrodon is frequently cited as Johnston, 1859, and its type species Astrodon johnstoni is usually cited as Leidy, 1865. Although Johnston’s publication does satisfy the Code’s requirements for published work, the lack of description means it does not satisfy the criteria of availability in Article 12 for names published before 1931. Astrodon was a nomen nudum until it was made available by Leidy in his subsequent description of the nominal genus with its single new nominal species. The correct authorship of both the genus Astrodon and its type species Astrodon johnstoni is therefore Leidy, 1865.
... Titanosauriforms is the most diverse sauropod clade in the Cretaceous, and it is represented on all continents (Aldirene et al., 2004;Carvalho et al., 2017;D'Emic, 2012D'Emic, , 2013Mannion et al., 2010Mannion et al., , 2013Mannion et al., , 2017Salgado et al., 2006). Titanosauriforms have the largest range of body size of any sauropod clade and includes both the largest known sauropods and some of the smallest (Wilson, 2006). ...
Previous and new fossils of sauropods are reported from the Papo-Seco Formation (lower Barremian, Lower Cretaceous) at Cabo Espichel, south of Lisbon, Portugal. The fossils were collected from the Boca do Chapim and Praia do Areia do Mastro sites. The sauropods and other vertebrate fossil remains from the Papo-Seco Formation occur in marls, sandstones and some conglomerates in a sedimentary succession interpreted as deposited in lagoonal and estuarine environments, under a tropical climate. The study of the available specimens, including teeth and postcranial remains, suggests the occurrence of Titanosauriform sauropods.
... Therefore, for this difference in manus morphology, we exclude Calorckosauripus as possible attribution. Vila et al. (2005;, 2013 reported many sauropod trackways from the Maastrichtian Tremp Formation of Spain. Pes tracks show four claw impressions laterally oriented and symmetrical, subrectangular to U-shaped manus tracks without claw impressions. ...
... 'Brachiosaurus' [24], Giraffatitan [25], Abydosaurus [26]), few non-titanosaurian somphospondylan taxa are represented by any cranial remains at all. Several non-titanosaurian somphospondylans preserve only teeth, including Astrophocaudia slaughteri [293], Borealosaurus wimani [310], Europatitan eastwoodi [311], Huabeisaurus allocotus [223,312], Sibirotitan astrosacralis [219] and Yongjinglong datangi [173]. Ligabuesaurus leanzai preserves teeth and a fragmentary maxilla [174,291,313], whereas teeth and a braincase are preserved in both Mongolosaurus haplodon [152,314] and Tambatitanis amicitiae [151,315]. ...
Titanosaurian sauropod dinosaurs were diverse and abundant throughout the Cretaceous, with a global distribution. However, few titanosaurian taxa are represented by multiple skeletons, let alone skulls. Diamantinasaurus matildae, from the lower Upper Cretaceous Winton Formation of Queensland, Australia, was heretofore represented by three specimens, including one that preserves a braincase and several other cranial elements. Herein, we describe a fourth specimen of Diamantinasaurus matildae that preserves a more complete skull—including numerous cranial elements not previously known for this taxon—as well as a partial postcranial skeleton. The skull of Diamantinasaurus matildae shows many similarities to that of the coeval Sarmientosaurus musacchioi from Argentina (e.g. quadratojugal with posterior tongue-like process; braincase with more than one ossified exit for cranial nerve V; compressed-cone–chisel-like teeth), providing further support for the inclusion of both taxa within the clade Diamantinasauria. The replacement teeth within the premaxilla of the new specimen are morphologically congruent with teeth previously attributed to Diamantinasaurus matildae, and Diamantinasauria more broadly, corroborating those referrals. Plesiomorphic characters of the new specimen include a sacrum comprising five vertebrae (also newly demonstrated in the holotype of Diamantinasaurus matildae), rather than the six or more that typify other titanosaurs. However, we demonstrate that there have been a number of independent acquisitions of a six-vertebrae sacrum among Somphospondyli and/or that there have been numerous reversals to a five-vertebrae sacrum, suggesting that sacral count is relatively plastic. Other newly identified plesiomorphic features include: the overall skull shape, which is more similar to brachiosaurids than ‘derived' titanosaurs; anterior caudal centra that are amphicoelous, rather than procoelous; and a pedal phalangeal formula estimated as 2-2-3-2-0. These features are consistent with either an early-branching position within Titanosauria, or a position just outside the titanosaurian radiation, for Diamantinasauria, as indicated by alternative character weighting approaches applied in our phylogenetic analyses, and help to shed light on the early assembly of titanosaurian anatomy that has until now been obscured by a poor fossil record.
... In lateral view, the proximal surface of the tibia is convex and posteriorly inclined, as in Dongbeititan, Janenschia, and Lavocatisaurus (Bonaparte et al. 2000;Wang et al. 2007;Mannion et al. 2019). The anterodorsal margin of the proximal epiphysis forms an almost right angle with the lateral surface of the bone ( Figure 14C, E), whereas the posterodorsal margin is more prominent, as seen in the rebbachisaurids Lavocatisaurus and Zapalasaurus, and the derived Titanosauriformes Huabeisaurus, Sauroposeidon, and Uberabatitan (Salgado et al. 2006;Rose 2007;Salgado and Carvalho 2008;D'Emic et al. 2013;Canudo et al. 2018). The cnemial fossa of the tibia is on the proximolateral surface of the bone, being concave and triangular in lateral view ( Figure 14C). ...
The Lohan Cura Formation (Albian) at the Cerro de los Leones locality (Neuquén Province, Patagonia, Argentina) yielded several fossil materials, especially sauropod specimens. Among these, Agustinia ligabuei includes postcranial elements of a single individual, with widely debated taxonomy and phylogeny. Here, we provide an extended osteological description and illustrations of the axial and appendicular elements of Agustinia, as well as a revised diagnosis. Moreover, the phylogenetic analysis including a new combination of morphological features recognises Agustinia as a basal Rebbachisauridae, closely related with other South American rebbachisaurids. Our results suggest a more diversified sauropod fauna in the Neuquén Basin, where different members of both neosauropod lineages (i.e. Macronaria and Diplodocoidea) survived in the same region during the Albian age. The reassessment of Agustinia as a basal rebbachisaurid improves our knowledge about the early stages of evolutionary history of Rebbachisauridae, adding new information on the morphological and taxonomic diversification of the clade during the Early Cretaceous of southwestern Gondwana.
... Barremian-lower Aptian deposits in Utah have produced the brachiosaurid Venenosaurus [255] and indeterminate titanosauriforms [256,257], and lower Aptian deposits in Maryland have produced abundant evidence of titanosauriforms [258][259][260][261][262][263]. The nontitanosaurian somphospondylan Sauroposeidon (=Paluxysaurus) spans the Aptian-Albian of Texas and Oklahoma [221,[264][265][266][267][268], and possibly Arkansas [269]; other titanosauriforms recorded from this interval include indeterminate forms from Nevada, Montana and Wyoming [270][271][272][273][274], the brachiosaurid Abydosaurus [2] and the somphospondylan Brontomerus [64,275] from Utah, and a brachiosaurid possibly referable to Cedarosaurus [276][277][278], the somphospondylan Astrophocaudia [276,278] and indeterminate forms [276] from Texas. The geologically youngest pre-'sauropod hiatus' sauropod records in North America date to the late Albian-early Cenomanian [136,272]; these are the late-surviving brachiosaurid Sonorasaurus from New Mexico [279,280], and titanosauriform teeth from the Mussentuchit Member of the Cedar Mountain Formation of Utah [281]. ...
... Barremian-lower Aptian deposits in Utah have produced the brachiosaurid Venenosaurus [255] and indeterminate titanosauriforms [256,257], and lower Aptian deposits in Maryland have produced abundant evidence of titanosauriforms [258][259][260][261][262][263]. The nontitanosaurian somphospondylan Sauroposeidon (=Paluxysaurus) spans the Aptian-Albian of Texas and Oklahoma [221,[264][265][266][267][268], and possibly Arkansas [269]; other titanosauriforms recorded from this interval include indeterminate forms from Nevada, Montana and Wyoming [270][271][272][273][274], the brachiosaurid Abydosaurus [2] and the somphospondylan Brontomerus [64,275] from Utah, and a brachiosaurid possibly referable to Cedarosaurus [276][277][278], the somphospondylan Astrophocaudia [276,278] and indeterminate forms [276] from Texas. The geologically youngest pre-'sauropod hiatus' sauropod records in North America date to the late Albian-early Cenomanian [136,272]; these are the late-surviving brachiosaurid Sonorasaurus from New Mexico [279,280], and titanosauriform teeth from the Mussentuchit Member of the Cedar Mountain Formation of Utah [281]. ...
The Upper Cretaceous Winton Formation of Queensland, Australia, has produced several partial sauropod skeletons, but cranial remains—including teeth—remain rare. Herein, we present the first description of sauropod teeth from this formation, based on specimens from three separate sites. An isolated tooth and a dentary fragment from the Diamantinasaurus matildae type locality are considered to be referable to that titanosaurian taxon. A single tooth from the D. matildae referred specimen site is similarly regarded as being part of that individual. Seventeen teeth from a new site that are morphologically uniform, and similar to the teeth from the two Diamantinasaurus sites, are assigned to Diamantinasauria. All sauropod teeth recovered from the Winton Formation to date are compressed-cone-chisel-shaped, have low slenderness index values (2.00–2.88), are lingually curved at their apices, mesiodistally convex on their lingual surfaces, and lack prominent carinae and denticles. They are markedly different from the chisel-like teeth of derived titanosaurs, more closely resembling the teeth of early branching members of the titanosauriform radiation. This provides further support for a ‘basal’ titanosaurian position for Diamantinasauria. Scanning electron microscope microwear analysis of the wear facets of several teeth reveals more scratches than pits, implying that diamantinasaurians were mid-height (1–10 m) feeders. With a view to assessing the spatio-temporal distribution of sauropod tooth morphotypes before and after deposition of the Winton Formation, we provide a comprehensive continent-by-continent review of the early titanosauriform global record (Early to early Late Cretaceous). This indicates that throughout the Early–early Late Cretaceous, sauropod faunas transitioned from being quite diverse at higher phylogenetic levels and encompassing a range of tooth morphologies at the start of the Berriasian, to faunas comprising solely titanosaurs with limited dental variability by the end-Turonian. Furthermore, this review highlights the different ways in which this transition unfolded on each continent, including the earliest records of titanosaurs with narrow-crowned teeth on each continent.
... The enamel is smooth, and the lingual surface is concave. The tooth crown is similar to that of other titanosauriform sauropods and is similar to those of Paluxysaurus Rose, 2007, which is probably a junior subjective synonym of Sauroposeidon Wedel, Cifelli & Sanders, 2000(D'Emic, 2013. ...
... Sauropod remains from the Antlers and other named units of the Trinity Group have a complex taxonomic history and the fossils from the Briar Site locality are non-diagnostic, with the exception of the tooth. Teeth and sparse remains from Texas were initially identified to the genera Astrodon Johnston, 1859 or Pleurocoelus Marsh, 1888 (see Langston, 1974), though both genera are now considered nomina dubia (D'Emic, 2013). Currently, four named species are identified from the Aptian/Albian Antlers Formation and Trinity Group: Cedarosaurus weiskopfae Tidwell, Carpenter & Brooks, 1999;Sauroposeidon proteles Wedel, Cifelli & Sanders, 2000;Paluxysaurus jonesi Rose, 2007; and Astrophocaudia slaughteri D'Emic, 2013. ...
... Currently, four named species are identified from the Aptian/Albian Antlers Formation and Trinity Group: Cedarosaurus weiskopfae Tidwell, Carpenter & Brooks, 1999;Sauroposeidon proteles Wedel, Cifelli & Sanders, 2000;Paluxysaurus jonesi Rose, 2007; and Astrophocaudia slaughteri D'Emic, 2013. The tooth from the Holly Creek matches well with the general "Astrodon" tooth morphology and is similar to sauropod teeth from the Aptian/Albian of Texas (Rose, 2007;D'Emic, 2013). The tooth from the Holly Creek Formation lacks the longitudinal lingual groove seen in Astrophocaudia slaughteri and is fairly similar to those described for Paluxysaurus jonesi by Rose (2007, fig 6), as Camarasaurus-like but less spatulate. ...
We present a previously discovered but undescribed late Early Cretaceous vertebrate fauna from the Holly Creek Formation of the Trinity Group in Arkansas. The site from the ancient Gulf Coast is dominated by semi-aquatic forms and preserves a diverse aquatic, semi-aquatic, and terrestrial fauna. Fishes include fresh- to brackish-water chondrichthyans and a variety of actinopterygians, including semionotids, an amiid, and a new pycnodontiform, Anomoeodus caddoi sp. nov. Semi-aquatic taxa include lissamphibians, the solemydid turtle Naomichelys , a trionychid turtle, and coelognathosuchian crocodyliforms. Among terrestrial forms are several members of Dinosauria and one or more squamates, one of which, Sciroseps pawhuskai gen. et sp. nov., is described herein. Among Dinosauria, both large and small theropods ( Acrocanthosaurus , Deinonychus , and Richardoestesia ) and titanosauriform sauropods are represented; herein we also report the first occurrence of a nodosaurid ankylosaur from the Trinity Group. The fauna of the Holly Creek Formation is similar to other, widely scattered late Early Cretaceous assemblages across North America and suggests the presence of a low-diversity, broadly distributed continental ecosystem of the Early Cretaceous following the Late Jurassic faunal turnover. This low-diversity ecosystem contrasts sharply with the highly diverse ecosystem which emerged by the Cenomanian. The contrast underpins the importance of vicariance as an evolutionary driver brought on by Sevier tectonics and climatic changes, such as rising sea level and formation of the Western Interior Seaway, impacting the early Late Cretaceous ecosystem.
... In summary, there are only two clear reports of neosauropods with four unguals on digits I-IV that fit with the morphological features of the pes tracks of Iniestapodus: the Early Cretaceous brachiosaurid Cedarosaurus 108,117,118 and the dicraeosaurid Dyslocosaurus 102,105 . Additionally, it should be noted that Jensen 113 reported a reduced fourth ungual phalanx in a pes of Camarasaurus, although other complete feet of this species only show three unguals 87,114 . ...
Sauropod remains are abundant on the Iberian Peninsula across the Jurassic-Cretaceous transition. Where the osteological record shows a high diversity of this kind of dinosaur, the ichnological findings are mainly limited to sauropod tracks characterized by kidney-shaped manus (with or without pollex impressions) and pes impressions with three claw imprints oriented laterally. Here, we present a new sauropod ichnotaxon, Iniestapodus burgensis, found at several exposures within the Las Sereas megatracksite (Burgos, Spain). These are preserved within lacustrine limestone strata of the Rupelo Formation (Tithonian–Berriasian). Iniestapodus burgensis is characterized by: semicircular manus tracks with small pollex impressions; unusual tetradactyl pes tracks with evidence of four claws oriented anteriorly (I–II) and laterally (III–IV), of variable sizes (short claw I and IV impressions, claw II and III being the largest). The combination of features and comparison with the osteological record allows us to propose a non-titanosaurian titanosauriform as a possible trackmaker. All the Iniestapodus tracks are represented by at least two different size classes of small and medium-sized individuals, and their trackways show different multidirectional orientations. The paleoenvironmental and paleoecological data suggest that Iniestapodus trackmakers were solitary individuals, likely representing different age classes, that crossed and used the Las Sereas shallow lacustrine-palustrine areas as their preferred habitat.
... The most common single co-ossification, or at least the most phylogenetically widespread, may be the fusion of the scapula and coracoid into a single element [used in e.g. Squamata (Dong, Wang & Evans, 2017); Rhynchocephalia (O'Brian et al., 2018); Sauropterygia (Rothschild, Clark & Clark, 2018); Pantestudines (Bever et al., 2015); Pseudosuchia (Walker, 1961;Brochu, 1995;Roberto-da-Silva et al., 2020); Pterosauria (Hone et al., 2012b); Dinosauria (Coombs & Marya nska, 1990;Currie & Zhao, 1993;Coria et al., 2013;D'emic, 2013;Griffin, 2018;Navalón et al., 2018)]. The fusion of these elements during ontogeny may represent the ancestral saurian condition (Griffin, 2018). ...
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life‐history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least‐inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260‐million‐year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. ‘juvenile’, ‘mature’) and provide routes for better clarity and cross‐study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method‐specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, ‘Ontogenetic Assessment’, be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well‐represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well‐constrained, empirically tested methods.