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Feeding envelopes of Brachiosaurus (left) and Sauroposeidon (right). The shapes of the feeding envelopes were probably complex; we have deliberately simplified them for the purposes of this illustration . Because volume increases with the cube of the linear dimension, the increase in neck length of 25 to 33% in Sauroposeidon would have effectively doubled the volume of its feeding envelope over that of Brachiosaurus (1.25~ = 1.95, 1.33~ = 2.35). The human figure is 1.8 m tall.
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Sauroposeidon proteles is a large brachiosaurid sauropod recently described from the Antlers Formation (Aptian-Albian) of southeastern Oklahoma. Sauroposeidon represents the culmination of brachiosaurid trends toward lengthening and lightening the neck, and its cervical vertebrae are characterized by extensive pneumatic structures. The elaboration...
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We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the...
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... The chambers in the vertebrae studied herein grade evenly from the large central cavity that occupies virtually the entire centrum at its midpoint, through a complex network of trabeculae toward the anteroposteriorly terminal portions of the vertebrae. That level of heterogeneity in chamber size is not seen in pterosaurs (see Buchmann et al. 2021, Williams et al. 2021, nor in extant birds-the closest analogue among pneumatic vertebrae would be the polycamerate and semicamellate vertebrae of some sauropod dinosaurs, which have large open chambers at the mid-centrum (camerae) that grade into smaller, thinwalled chambers near the extremities of the centrum (camellae; Wedel et al. 2000, Wedel 2003a). In these sauropod vertebrae, the smallest pneumatic chambers are still much larger than the trabecular spaces of apneumatic vertebrae from the same taxa (e.g. ...
... 7.7). The smallest pneumatic spaces in the vertebrae of birds and pterosaurs approach the size of trabecular spaces in apneumatic, marrow-filled bone, but the size of the pneumatic spaces tends to be consistent throughout the internal structure, giving the vertebrae a honeycombed appearance-the fully camellate condition described by Britt (1993), Wedel et al. (2000), and Wedel (2003a). Criteria for diagnosing pneumaticity in fossil vertebrates have been reviewed by many authors ( Janensch 1947, Britt 1993, Witmer 1997, Wedel 2003a, b, 2005, O'Connor 2006, Butler, Barrett and Gower 2012, Yates et al. 2012. ...
The Triassic was a key period in the evolution of vertebrates, and reptiles in particular, giving rise to a plethora of successful lineages, some of which are still extant. One of the groups that flourished during the early Mesozoic were the tanysaurians (Archosauromorpha: Tanysauria). They had elongate neck vertebrae that in some genera reached extreme proportions. Here, we provide the first comprehensive description of the internal structure of these extraordinary elements, focusing on the famously bizarre Tanystropheus. Through computed tomography and sectioning, we were able to reveal some intriguing features comparable to those seen in pterosaurs and birds. However, contrary to what we see in pneumatic bones, cervicals of tanysaurians contain a singular voluminous cavity. This results in a cylindrical structure in these vertebrae, which likely provided durability, while contributing less to the weight of the neck. These insights are relevant for better understanding of a unique and extreme anatomy among tetrapods, which evolved as a result of very strict selection for some particular function. Importantly, our findings demonstrate that major modifications of the internal anatomy of vertebrae were not unique to derived avemetatarsalians (pterosaurs and dinosaurs), but more widespread among reptiles.
... This method consists of detecting the conjoint presence of an external pneumatic foramen connecting with internal camerae or camellae. Earlier hypotheses based on sauropod vertebrae indicated the evolution of the internal pneumatic chambers evolved from larger camerae into smaller camellae, from early neosauropods to the late titanosaurs (Wedel, 2003;Wedel et al., 2000). Recent evidence from the earliest sauropodomorphs in the Carnian found apneumatic skeletons in Buriolestes and Pampadromaeus and delicate camellate-like pneumatic protocamerate trabeculae in the Norian unaysaurid Macrocollum (Aureliano et al., 2022. ...
... We followed Wilson's nomenclature for vertebral fossae and laminae (Wilson, 1999(Wilson, , 2012Wilson et al., 2011) Wedel's, O'Connor's, and Aureliano's works for the terminologies and description of unambiguous vertebral pneumatic structures (Aureliano et al., 2021;O'Connor, 2006;Wedel, 2003Wedel, , 2007Wedel et al., 2000). ...
Recent evidence suggests that the invasive air sac system evolved at least three times independently in avemetatarsalians: in pterosaurs, sauropodomorphs and theropods. Data from sauropodomorphs showed that the pneumatic architecture in vertebrae first developed in camellate‐like trabeculae in the Triassic, later in camerate systems in Jurassic neosauropods, and finally camellate tissue in Cretaceous titanosaurs. This evolutionary trajectory has support from a considerable sampling of sauropodomorph taxa. However, the evolution of pneumatic bone tissues in Theropoda is less understood. We analyzed the computed tomography of Majungasaurus and Rahonavis , using densitometry rendering to differentiate the microarchitecture along the presacral axial skeleton of late Ceratosaurians and early Paravians. We also compared these results with scans of other theropod clades. Our analysis revealed an increase in pneumatic complexity in early paravians compared to the ceratosaurians. Majungasaurus presents some apneumatic neural spines, a condition also observed in Allosaurus . Majungasaurus also features some apneumatic centra despite the presence of lateral pneumatic fossae. This raises caution when evaluating PSP solely based on external morphology. We also found evidence of distinct patterns of PSP in maniraptorans. Considering that Majungasaurus , a late abelisaurid, inherited from their ceratosaurian ancestors, some apneumatic elements such as the neural spine and some centra, Rahonavis , an early paravian, took a different trajectory toward the full pneumatization of the axial skeleton. This characteristic provided paravians an advantage in gliding and flying. Also, unlike Sauropoda, pneumaticity in Theropoda apparently developed by increasing chamber volumes toward paravians. Similar studies on early Theropoda are needed to elucidate their condition and better describe the evolutionary trajectory of different groups.
... Mannion et al. 2019). Other important taxa to understand the change of body plans within early Macronaria are the Brachiosauridae, several somphospondylans with uncertain affinities (such as Sauroposeidon Wedel, Cifelli &Sanders, 2000 andEuhelopus Wiman, 1929), and the early-diverging titanosaurs (Bates et al. 2016). Among these taxa that could reach large proportions are Brachiosaurus Riggs, 1903 and Argentinosaurus Bonaparte Basal Macronaria are characterized by relatively gracile limbs that are long in relationship to the trunk (sensu Carrano 2005). ...
... Mannion et al. 2019). Other important taxa to understand the change of body plans within early Macronaria are the Brachiosauridae, several somphospondylans with uncertain affinities (such as Sauroposeidon Wedel, Cifelli &Sanders, 2000 andEuhelopus Wiman, 1929), and the early-diverging titanosaurs (Bates et al. 2016). Among these taxa that could reach large proportions are Brachiosaurus Riggs, 1903 and Argentinosaurus Bonaparte Basal Macronaria are characterized by relatively gracile limbs that are long in relationship to the trunk (sensu Carrano 2005). ...
... 1). Contrary to the ventral bracing hypothesis, several authors postulated a new hypothesis that can be summarized as the tensor member hypothesis, in which the cervical ribs are regarded as ossified tendons that were used to transfer tensions over long distances, such that the bellies of the neck muscles could be displaced towards the trunk, thus reducing neck weight (Christian and Heinrich 1998, Wedel et al. 2000, Christian 2002, Christian and Dzemski 2011, Klein et al. 2012. However, the tensor member hypothesis predicts the presence histologically of longitudinally oriented mineralized collagen fibres, as present in ossified tendons of birds and other non-avian dinosaurs (Organ andAdams 2005, Klein et al. 2012). ...
Trigonosaurus pricei is a small to medium-sized sauropod dinosaur (Sauropoda: Titanosauria) from the Late Cretaceous Bauru Group of Brazil that is known from a significant amount of recovered axial elements [four cervical vertebrae, 10 dorsal vertebrae, sacrum (MCT 1488-R), and 10 caudal vertebrae (MCT 1719-R)]. In this biomechanical work, we approach the hypothesis of the cartilaginous neutral pose and the range of motion of the axial series of Trigonosaurus. The results show that this sauropod could be capable of high elevation of the neck resulting from morphological adaptations of the cervicodorsal region on dorsal (D) vertebrae D2 and D3 (e.g. postzygapophyses of D2 positioned over the vertebral centrum and prezygapophyses of D3 over the anterior vertebral centrum). This implies that D2 articulates (cartilaginous neutral posture) with D3 only at a strong dorsally directed angle, resulting in a shift in the direction of the neck to a more elevated posture. Furthermore, the tail attributed to Trigonosaurus as a paratype could be oriented in the horizontal ‘direction’ and presented a sigmoidal ‘shape’. This work contributes
generally to the understanding of variation in the body plan of sauropods and, more specifically, to the feeding strategy of small and medium-sized titanosaurs from semi-arid regions of Gondwana
... For the osteological description we mainly followed the nomenclature of [33,34], and [35]. The elongation of the caudal vertebrae was calculated according to the Elongation Index (EI) sensu [36] as the anteroposterior length of the centrum divided by the midline height of the posterior articular surface. ...
... This element lacks portions of the centrum margins, both prezygapophyseal processes, and the posterior portion of the neural spine. The centrum is longer than high, having an elongation index (EI, sensu [36]) of 1.3. Both anterior and posterior articular surfaces have similar measurements, being as wide as they are tall (Fig. 3G, I; Table 1). ...
... The initial analysis using the data set of [37] retrieved 194 most parsimonious trees (MPTs) of 1602 steps. The Abbreviations ah, anterior height of the centrum; aw, anterior width of the centrum; cl, centrum length; EI, elongation index sensu [36]; ph, posterior height of the centrum; pw, posterior width of the centrum; sh, height of the neural spine from the zygapophyses; sl, anteroposterior length of the neural spine; sw, width of the neural spine. All measurements are in centimeters * indicates that a measurement is estimated Figure S1) had the same polytomies seen in previous iterations of the phylogenetic dataset ( [37,77]). ...
The Portezuelo Formation preserves an outstanding record of the upper Turonian – lower Coniacian. Despite the discovery of a significant quantity of sauropod fossil material from the formation, only two species have been formally described to date: Malarguesaurus florenciae and Futalognkosaurus dukei. Here we present new sauropod material mostly composed of non-articulated caudal vertebrae (MCF-PVPH 916 and 917) that belong to two titanosauriforms on the basis of the following features: anterior caudal vertebrae with procoelous-opisthoplatyan articulations, transverse processes that reach the posterior articular face of the centrum and neural spines with a transverse width of around 50% of their anteroposterior length; anterior and middle caudal vertebrae with the neural arch restricted to the anterior half of the centrum; middle caudal centra with circular cross-section. Phylogenetic analysis recovers the new material in close relation to Malarguesaurus within a monophyletic clade at the base of Somphospondyli. This clade shares large pedicel height with a vertical anterior border on the middle caudal vertebrae, a vertical orientation of the neural spines on the distalmost middle caudal vertebrae and proximalmost posterior caudal vertebrae, and subequal relative lengths of the proximal ulnar condylar processes. The specimens presented here are distinct not only from Futalognkosaurus, but also from other indeterminate titanosaurian remains from the same formation. However, there are no significant differences between the specimen MCF-PVPH 917 and Malarguesaurus, but there are differences between the posterior caudal vertebrae of MCF-PVPH 916 and Malarguesaurus, so they could be considered different species. Whilst we err on the side of caution in not naming new taxa here, the two specimens significantly expand what we know about sauropods in the Turonian–Coniacian ecosystems of Patagonia, which will continue to do so as more material is discovered.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12862-024-02280-9.
... For the osteological description we mainly followed the nomenclature of [16], [29], and [30]. The elongation of the caudal vertebrae was calculated according to the Elongation Index (EI) sensu [31]as the anteroposterior length of the centrum divided by the midline height of the posterior articular surface. ...
... This element lacks portions of the centrum margins, both prezygapophyseal processes, and the posterior portion of the neural spine. The centrum is longer than high, having an elongation index (EI, sensu [31]) of 1.3. Both anterior and posterior articular surfaces have similar measurements, being as wide as they are tall ( Table 1). ...
... Table 1 Measurements of caudal vertebrae from the Portezuelo Formation. Abbreviations: ah, anterior height of the centrum; aw, anterior width of the centrum; EI, elongation index sensu [31]; lc, length of the centrum; ph, posterior height of the centrum; pw, posterior width of the centrum; sh, height of the neural spine; sl, length of the neural spine; sw, width of the neural spine. All measurements are in centimeters. ...
The Portezuelo Formation preserves an outstanding record of the upper Turonian - lower Coniacian of Gondwana. Despite the discovery of a significant amount of sauropod fossil material from the Formation, only two species have been formally described to date: Malarguesaurus florenciae and Futalognkosaurus dukei . Here we present new sauropod material mostly composed of non-articulated caudal vertebrae that belong to at least two different titanosauriforms on the basis of following features: anterior caudal vertebrae with procoelous-opistoplatyan articulations, transverse processes that reach the posterior articular face of the centrum and neural spines with a lateromedial width of ~ 50% of its anteroposterior length; anterior and middle caudal vertebra with the neural arch restricted to the anterior half of the centrum; middle caudal centrum with circular cross-section. Phylogenetic analysis recovers the new material in close relation to Malarguesaurus within a monophyletic clade sister to Somphospondily. This clade shares large pedicel height with a vertical anterior border on the middle caudal vertebrae, a vertical orientation of the neural spines on the distalmost middle caudal vertebrae and proximalmost posterior caudal vertebrae, and subequal relative lengths of the proximal ulnar condylar processes. The specimens presented here are distinct not only from Malarguesaurus and Futalognkosaurus , but also from other indeterminate titanosaur remains from the same formation. Whilst we err on the side of caution in not naming new taxa here, the two specimens significantly expand what we know about sauropods in the Turonian-Coniacian ecosystems of Patagonia, which will continue to do so as more material is discovered.
... Long cervical ribs that extend posteriorly under one or more subsequent centra are primitive for sauropods (Klein et al. 2012). Particularly elongated cervical ribs evolved independently in mamenchisaurids (Young and Zhao 1972;Russell and Zheng 1993;Zhang et al. 2018) and in basal titanosauriforms such as Giraffatitan (Janensch 1950) and Sauroposeidon (Wedel et al. 2000). Cervical ribs in these taxa overlapped, forming vertically-stacked bundles. ...
... The prominent dorsal process in a cervical rib of Brontosaurus parvus CM 555 shows that at least the potential for bifurcation was present in both Apatosaurus and Brontosaurus. Wedel et al. (2000) proposed that the cervical rib shafts of sauropods were ossified tendons. That hypothesis has been confirmed by numerous histological studies ( Abbreviation: dp, dorsal process. ...
Bifurcated cervical ribs have evolved infrequently in dinosaurs. Previously documented examples include those in abelisaurid theropods, leptoceratopsid ceratopsians, and turiasaurian sauropods. In apatosaurine sauropods a spectrum of cervical rib morphologies exists, from cervical ribs with small dorsal processes extending from the shafts to completely bifurcated cervical ribs. Similar dorsal processes are present in the dicraeosaurid Dicraeosaurus. The presence of dorsal processes and bifurcated cervical ribs suggests that the hypaxial neck muscles that inserted on the cervical ribs were oriented in divergent directions. In all the dinosaurian examples we have found, the cervical ribs are maximally bifurcated in the middle of the cervical series. We hypothesize that bifurcated cervical ribs are traces of diverging neck muscles that provided improved control in the middle of the neck, at some distance from both the head and the trunk.
... This is important to our study for two reasons. Sauropods have been hypothesized to have evolved long necks so as to extend their feeding envelopes, which thereby allowed them to consume more tree-matter while remaining stationary [90,91]. According to this hypothesis, they could have spent several hours standing at the base of a conifer, stripping its branches, before moving to an adjacent tree to repeat the process, without expending much energy on locomotion. ...
Dinosaur foraging ecology has been the subject of scientific interest for decades, yet much of what we understand about it remains hypothetical. We wrote an agent-based model (ABM) to simulate meat energy sources present in dinosaur environments, including carcasses of giant sauropods, along with living, huntable prey. Theropod dinosaurs modeled in this environment (specifically allosauroids, and more particularly, Allosaurus Marsh, 1877) were instantiated with heritable traits favorable to either hunting success or scavenging success. If hunter phenotypes were more reproductively successful, their traits were propagated into the population through their offspring, resulting in predator specialists. If selective pressure favored scavenger phenotypes, the population would evolve to acquire most of their calories from carrion. Data generated from this model strongly suggest that theropods in sauropod-dominated systems evolved to detect carcasses, consume and store large quantities of fat, and dominate carcass sites. Broadly speaking, selective forces did not favor predatory adaptations, because sauropod carrion resource pools, as we modeled them, were too profitable for prey-based resource pools to be significant. This is the first research to test selective pressure patterns in dinosaurs, and the first to estimate theropod mass based on metabolic constraints.
... The resulting internal air spaces exhibit a wide range of sizes, shapes, and branching patterns. Wedel et al. (2000) built upon the system of Britt (1993) to distinguish large, rounded chambers (camerae) that branch regularly into smaller units, if at all, from networks of smaller, irregularly branching chambers (camellae). Wedel (2003b) added the distinction that camerate pneumaticity features thicker septa separating chambers than camellate pneumaticity does. ...
... Sauropod taxa are generally characterized by one form of pneumaticity or the other, with some phylogenetic influence on the distribution of camerate and camellate pneumaticity (Wedel, 2003a). Camellae predominate later in sauropod evolution with the diversification of the Titanosauriformes, although apparent reversals exist within the clade (Wedel, 2003a;Wedel et al., 2000). ...
... The presence of this type of pneumaticity in presacral vertebrae has been recovered as a titanosauriform synapomorphy by many phylogenetic analyses (e.g., Mannion et al., 2013;Sanz et al., 1999;Wilson, 2002). Wedel et al. (2000) proposed that camellate pneumaticity evolved alongside elongated cervical vertebrae as a means of weight reduction, implying greater weight savings in taxa with camellate pneumaticity than camerate pneumaticity. Wedel (2003b:248) offered another explanation, that camellate pneumaticity is "biomechanically more effective" than camerate pneumaticity in the context of neck length evolution. ...
Many sauropod dinosaurs exhibit extensive postcranial skeletal pneumaticity that may have facilitated the
evolution of extreme body sizes. Among titanosauriforms, complex, irregularly branching camellate chambers are found
throughout the presacral vertebral column, often invading the ribs and ilium as well. To explore the function of these
camellae, including reduction in bone volume, pneumaticity was examined in a titanosaur sauropod from the Upper
Cretaceous Black Peaks Formation of Big Bend National Park, Texas, that includes pneumatic dorsal ribs and ilia. Using
natural breaks to non-destructively observe the internal structure, patterns of camellate pneumaticity are described for the
dorsal vertebrae, ribs, and ilium. The space occupied by camellae is quantified as the airspace proportion, which is
reported here in a sauropod ilium for the first time. Airspace proportions exceed 70% in parts of the dorsal vertebrae and
ilium, with lower values near the cotyles of the vertebral centra and the acetabulum. Values in the ribs decrease distally.
These values are not appreciably different from those of sauropods with simpler camerate pneumaticity. If camellae did
not offer greater weight reduction than camerae, they may have enhanced structural strength, as the chambers appear to
align with stress in the vertebral centra and ilium. Apneumatic trabecular bone around the acetabulum, preacetabular
process, and postzygapophyses, however, may indicate stresses too great for camellate bone to bear, although an
ontogenetic influence cannot be ruled out.
... The posterior cotyle and a small portion of the anterior condyle are preserved. Both pleurocoels are present; the left is significantly smaller and penetrates deeper into the centrum (Fig. 3A), whereas the right pleurocoel is larger and shallower, hinting at potential asymmetry in the expression of pneumatic features as previously noted in other sauropod fossils (e.g., Wedel et al., 2000;Wedel, 2003). The remnants of the neural canal floor are present near the preserved fragment of the neural arch (Fig. 3A). ...
... Computed tomographic (CT) scans of the dorsal vertebrae were taken to investigate their internal morphology and pneumatic qualities (Fig. 7). All are fully camellate, corresponding to the somphospondylous pattern of pneumaticity (e.g., Wedel et al., 2000;Wedel, 2003). The centrum typically contains only small camellae and deep, elliptical pleurocoels, whereas the neural arch houses a few larger, rounded camellae that are mostly related with the pneumatization of the diapophysis. ...
... All Igai dorsal vertebrae show a fully camellate pattern of internal bony structure that is comparable to that seen in vertebrae of other somphospondylous titanosauriforms (Wedel et al., 2000;Wedel, 2003;Aureliano et al., 2021). The architecture and distribution of the camellae appears similar to the patterns observed in cervical vertebrae of Uberabatitan ribeiroi (Silva Junior et al., 2019:figs. ...
Dinosaur fossils from the latest Cretaceous (Campanian–Maastrichtian) of Africa and the Arabian Peninsula are rare. Most discoveries to date have consisted of limited fossils that have precluded detailed phylogenetic and paleobiogeographic interpretations. Fortunately, recent discoveries such as the informative Egyptian titanosaurian sauropod dinosaur Mansourasaurus shahinae are beginning to address these long-standing issues. Here we describe an associated partial postcranial skeleton of a new titanosaurian taxon from the Upper Cretaceous (Campanian) Quseir Formation of the Kharga Oasis, Western Desert of Egypt. Consisting of five dorsal vertebrae and 12 appendicular elements, Igai semkhu gen. et sp. nov. constitutes one of the most informative dinosaurs yet recovered from the latest Cretaceous of Afro-Arabia. The relatively gracile limb bones and differences in the coracoid and metatarsal I preclude referral of the new specimen to Mansourasaurus. Both model-based Bayesian tip-dating and parsimony-based phylogenetic analyses support the affinities of Igai semkhu with other Late Cretaceous Afro-Eurasian titanosaurs (e.g., Mansourasaurus, Lirainosaurus astibiae, Opisthocoelicaudia skarzynskii), a conclusion supported by posterior dorsal vertebrae that lack a postzygodiapophyseal lamina, for example. Igai semkhu strengthens the hypothesis that northern Africa and Eurasia shared closely related terrestrial tetrapod faunas at the end of the Cretaceous and further differentiates this fauna from penecontemporaneous assemblages elsewhere in Africa, such as the Galula Formation in Tanzania, that exhibit more traditional Gondwanan assemblages. At present, the specific paleobiogeographic signal appears to vary between different dinosaur groups, suggesting that Afro-Arabian Cretaceous biotas may have experienced evolutionary and paleobiogeographic histories that were more complex than previously appreciated.
... The evaluation of unambiguous PSP requires the identification of deep vertebral fossae containing foramina connecting with internal pneumatic structures such as camerae and camellae (O'Connor, 2006). Unambiguous PSP has been extensively reported in neosauropods, especially titanosauriforms (Wedel et al., 2000;Wedel, 2003;Schwarz & Fritsch, 2006;Woodward and Lehman 2009;Cerda, Salgado, & Powell, 2012;Zurriaguz & Powell, 2015;Bandeira et al., 2016). In contrast, few studies have focused on the origins of these diverticula within early sauropodomorphs, and much of the knowledge on nonsauropod sauropodomorphs is based on scarce evidence (Butler et al., 2012;Wedel, 2007Wedel, , 2009Yates et al., 2012). ...
... We apply Wilson's terms to describe vertebral laminae, fossae, and their landmarks (Wilson, 1999(Wilson, , 2012Wilson et al., 2011), Wedel's for vertebral pneumaticity (Wedel, 2003(Wedel, , 2007Wedel et al., 2000), and O'Connor's method to evaluate unambiguous PSP (O'Connor, 2006). CloudCompare v2.12.4 (CloudCompare, 2018) to process the data, to generate 3D reconstructions, and to apply density-based color grades based on bone tissues (Aureliano et al., 2020). ...
... Macrocollum also presented a new type of pneumatic tissue, showing properties of both camarae and camellae as defined by Wedel et al. (2000). We named this tissue "protocamerae" (see ptc in Figures 2 and 3). ...
One of the most remarkable features in sauropod dinosaurs relates to their pneu-matized skeletons permeated by a bird-like air sac system. Many studies described the late evolution and diversification of this trait in mid to late Meso-zoic forms but few focused on the origin of the invasive respiratory diverticula in sauropodomorphs. Fortunately, it is possible to solve this thanks to the boom of new species described in the last decade as well as the broad accessibility of new technologies. Here we analyze the unaysaurid sauropodomorph Macrocollum itaquii from the Late Triassic (early Norian) of southern Brazil using micro-computed tomography. We describe the chronologically oldest and phylogeneti-cally earliest unambiguous evidence of an invasive air sac system in a dinosaur. Surprisingly, this species presented a unique pattern of pneumatization in non-sauropod sauropodomorphs, with pneumatic foramina in posterior cervical and anterior dorsal vertebrae. This suggests that patterns of pneumatization were not cladistically consistent prior to the arrival of Jurassic eusauropods. Additionally, we describe the protocamerae tissue, a new type of pneumatic tissue with properties of both camellae and camerae. This reverts the previous hypothesis which stated that the skeletal pneumatization first evolved into camarae, and derived into delicate trabecular arrangements. This tissue is evidence of thin camellate-like tissue developing into larger chambers. Finally, Macrocollum is an example
