Figure 11 - uploaded by Michael D'Emic
Content may be subject to copyright.
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.
Source publication
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...
Context in source publication
Context 1
... 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 ...
Citations
... 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.
... Royo-Torres et al. 2009; Carballido et al. 2011, 2017; Carballido & Sander 2014; Lacovara et al. 2014; Gonz alez-Riga et al. 2016; Tykoski & Fiorillo 2016; Britt et al. 2017; Fern andez-Baldor et al. 2017) or a somphospondylan (e.g. Curry Rogers 2005; You et al. 2008; Gonz alez Riga et al. 2009; Mannion 2010; Mateus et al. 2011; Sekiya 2011; Taylor et al. 2011;Zaher et al. 2011;D'Emic 2012D'Emic , 2013, 2017L€ u et al. 2013;Mannion et al. 2013Mannion et al. , 2017Mannion et al. , 2019Xing et al. 2015;R. D. F. Mart ınez et al. 2016;D'Emic et al. 2016;Gorscak & O'Connor 2016;Poropat et al. 2016;Averianov et al. 2018;Gonz alez Riga et al. 2018). ...
Fossil-rich deposits from the Middle and Late Jurassic of China have yielded a diverse array of sauropod dinosaurs, including numerous species referred to Mamenchisaurus and Omeisaurus. Despite an abundance of fossils and a proliferation of taxa, the anatomy of Middle–Late Jurassic Chinese sauropods remains poorly documented. Here, we comprehensively redescribe and illustrate Klamelisaurus gobiensis from the Middle–Late Jurassic Shishugou Formation of northwest China. Phylogenetic analyses conducted under parsimony and time-calibrated Bayesian optimality criteria consistently recover Klamelisaurus as a member of a predominantly Chinese radiation of exceptionally long-necked eusauropods that includes Mamenchisaurus spp., Chuanjiesaurus, Qijianglong and Wamweracaudia. In most analyses, this lineage also includes Euhelopus, reviving a ‘traditional’ Euhelopodidae and calling into question the macronarian affinities of Euhelopus. Klamelisaurus shares several features with Euhelopus that are unique to a subset of East Asian taxa or rare among sauropods, including a convex ventral margin of the prezygodiapophyseal lamina in middle–posterior cervical vertebrae, a ventrally bifurcated postzygodiapophyseal lamina in posterior cervical vertebrae, and development of a rugose projection extending anteriorly from the epipophysis into the spinodiapophyseal fossa in most cervical vertebrae. Anatomical comparisons of the cervical vertebrae of Klamelisaurus to several other sauropodomorphs and insights from myological studies of extant archosaurs strongly suggest that this latter structure, often considered part of an epipophyseal-prezygapophyseal lamina, is an epaxial muscle scar that is distinct from pneumatic structures of the lateral surface of the neural spine. The phylogenetic and comparative anatomical data presented here provide a foundation for future revision of the taxonomy and systematics of sauropods from the Junggar and Sichuan basins.
... Paedomorphosis provides a mechanistic explanation for the convergent evolution of small, pencil-like teeth in diplodocoid and titanosaurid sauropods 24,39 . As is the case in other tetrapod groups, convergent developmental perturbations may result in similar morphologies 30 . ...
Rare occurrences of dinosaurian embryos are punctuated by even rarer preservation of their development. Here we report on dental development in multiple embryos of the Early Jurassic Lufengosaurus from China, and compare these to patterns in a hatchling and adults. Histology and CT data show that dental formation and development occurred early in ontogeny, with several cycles of tooth development without root resorption occurring within a common crypt prior to hatching. This differs from the condition in hatchling and adult teeth of Lufengosaurus, and is reminiscent of the complex dentitions of some adult sauropods, suggesting that their derived dental systems likely evolved through paedomorphosis. Ontogenetic changes in successive generations of embryonic teeth of Lufengosaurus suggest that the pencil-like teeth in many sauropods also evolved via paedomorphosis, providing a mechanism for the convergent evolution of small, structurally simple teeth in giant diplodocoids and titanosaurids. Therefore, such developmental perturbations, more commonly associated with small vertebrates, were likely also essential events in sauropod evolution. Dinosaurs had some of the most complex dentitions known. Here, Reisz et al. characterize dental development across embryonic, hatchling and adult Lufengosaurus, an Early Jurassic sauropodomorph dinosaur, and suggest that derived sauropod dentition evolved by paedomorphosis (juvenilization).
