[Paleontology • 2018] Saltriovenator zanellai • The Oldest Ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, Sheds Light on the Evolution of the Three-fingered Hand of Birds

Saltriovenator zanellai 

Dal Sasso​, Maganuco & Cau, 2018

    DOI: 10.7717/peerj.5976 

Abstract 

The homology of the tridactyl hand of birds is a still debated subject, with both paleontological and developmental evidence used in support of alternative identity patterns in the avian fingers. With its simplified phalangeal morphology, the Late Jurassic ceratosaurian Limusaurus has been argued to support a II–III–IV digital identity in birds and a complex pattern of homeotic transformations in three-fingered (tetanuran) theropods. We report a new large-bodied theropod, Saltriovenator zanellai gen. et sp. nov., based on a partial skeleton from the marine Saltrio Formation (Sinemurian, lowermost Jurassic) of Lombardy (Northern Italy). Taphonomical analyses show bone bioerosion by marine invertebrates (first record for dinosaurian remains) and suggest a complex history for the carcass before being deposited on a well-oxygenated and well-illuminated sea bottom. Saltriovenator shows a mosaic of features seen in four-fingered theropods and in basal tetanurans. Phylogenetic analysis supports sister taxon relationships between the new Italian theropod and the younger Early Jurassic Berberosaurus from Morocco, in a lineage which is the basalmost of Ceratosauria. Compared to the atrophied hand of later members of Ceratosauria, Saltriovenator demonstrates that a fully functional hand, well-adapted for struggling and grasping, was primitively present in ceratosaurians. Ancestral state reconstruction along the avian stem supports 2-3-4-1-X and 2-3-4-0-X as the manual phalangeal formulae at the roots of Ceratosauria and Tetanurae, confirming the I–II–III pattern in the homology of the avian fingers. Accordingly, the peculiar hand of Limusaurus represents a derived condition restricted to late-diverging ceratosaurians and cannot help in elucidating the origin of the three-fingered condition of tetanurans. The evolution of the tridactyl hand of birds is explained by step-wise lateral simplification among non-tetanuran theropod dinosaurs, followed by a single primary axis shift from digit position 4 to 3 at the root of Tetanurae once the fourth finger was completely lost, which allowed independent losses of the vestigial fourth metacarpal among allosaurians, tyrannosauroids, and maniraptoromorphs. With an estimated body length of 7.5 m, Saltriovenator is the largest and most robust theropod from the Early Jurassic, pre-dating the occurrence in theropods of a body mass approaching 1,000 Kg by over 25 My. The radiation of larger and relatively stockier averostran theropods earlier than previously known may represent one of the factors that ignited the trend toward gigantism in Early Jurassic sauropods.

Figure 1: Fossil location and geological setting. (A–C) Outline maps of Italy, Lombardy, Varese Province, and Saltrio Municipality; (D) satellite view of the Saltrio area, with map marker indicating the Saltrio quarry; (E) map marker indicating the stratigraphic log in the Saltrio quarry; (F) the ammonite Paracoroniceras cf. gmuendense and (G) the nautiloid Cenoceras striatum, both found associated in the layer containing the dinosaur bones; (H) glauconite present as accessory mineral in block C (counterpart of block A of Fig. 2); (I) the discordance between the Dolomia Principale Fm. and the Saltrio Fm.; (J) thin sections of the layer embedding the dinosaur bones; (K) stratigraphic log of the Saltrio quarry, based on Croce (2005), with geological time scale and ammonites zones based on Sacchi Vialli (1964) and Ogg & Hinnov (2012). Abbreviations: c, crinoids; f, foraminifers; g, gastropods; o, ostracods. Scale bars equal 200 km in (A), 30 km in (B), six km in (C), one km in (D), one mm in (K), and 150 cm in (L). Photos by F. Berra, G. Bindellini, M. Croce, and G. Pasini; drawings by M. Croce and S. Maganuco.

Figure 1: Fossil location and geological setting.
(A–C) Outline maps of Italy, Lombardy, Varese Province, and Saltrio Municipality.

Scale bars equal 200 km in (A), 30 km in (B), six km in (C).

Figure 1: Fossil location and geological setting.
 (D) satellite view of the Saltrio area, with map marker indicating the Saltrio quarry; (E) map marker indicating the stratigraphic log in the Saltrio quarry; (F) the ammonite Paracoroniceras cf. gmuendense and (G) the nautiloid Cenoceras striatum, both found associated in the layer containing the dinosaur bones; (H) glauconite present as accessory mineral in block C (counterpart of block A of Fig. 2); (I) the discordance between the Dolomia Principale Fm. and the Saltrio Fm.; (J) thin sections of the layer embedding the dinosaur bones; (K) stratigraphic log of the Saltrio quarry, based on Croce (2005), with geological time scale and ammonites zones based on Sacchi Vialli (1964) and Ogg & Hinnov (2012). Abbreviations: c, crinoids; f, foraminifers; g, gastropods; o, ostracods.

Scale bars equal one mm in (K), and 150 cm in (L). Photos by F. Berra, G. Bindellini, M. Croce, and G. Pasini; drawings by M. Croce and S. Maganuco.

Figure 2: Taphonomy of the Saltrio theropod (block A). Bones of Saltriovenator mapped in temporal sequence (A–C), gradually emerging from the embedding rock during acid preparation of block A. Numbers refer to each fragment, not to a specific anatomical position. The latter is reported in other figures, for fragments that were later reconnected into more complete bones. Abbreviations as in text, and as follows: ind, indeterminate bone; ir, indeterminate rib; l (left) and r (right) are specified for fragments of paired bones certainly (appendicular elements) or tentatively (ribs) positioned in the skeleton. Macroborings facing front, side and back are mapped respectively with yellow circles, semicircles, and hatched circles. Scale bars equal 10 cm. Photos by G. Bindellini and C. Dal Sasso.

Figure 4: Selected elements used in the diagnosis of Saltriovenator zanellai n. gen. n. sp. Right humerus in medial (A), frontal (B) and distal (C) views; (D) left scapula, medial view; (E) right scapular glenoid and coracoid, lateral view; (F) furcula, ventral view; tooth, labial (G) and apical (H) views; (I) left humerus, medial view; right second metacarpal in dorsal (J), lateral (L) and distal (N) views; first phalanx of the right second digit in dorsal (K), lateral (M) and proximal (O) views; (P–T) right third digit in proximal, dorsal and lateral views; (U) right distal tarsal IV, proximal view; third right metatarsal in proximal (V) and frontal (X) views; second right metatarsal, proximal (W) and frontal (Y) views; (Z) reconstructed skeleton showing identified elements (red).

Abbreviations as in text, asterisks mark autapomorphic traits. 

Scale bars: 10 cm in (A)–(E), (I), and (U)–(Y); two cm in (F), and (J)–(T); one cm in (G). 

Photos by G. Bindellini, C. Dal Sasso and M. Zilioli; drawing by M. Auditore.

Figure 5: Cranio-mandibular fragments, tooth, and ribs of Saltriovenator zanellai. Indeterminate cranial fragment (A–B); right splenial in lateral (C), rostral (D) and ventral (E) views; right prearticular in lateral (F) and rostral views (G); sketch of the right prearticular of MOR 693 (Allosaurus fragilis) with virtual cross-section (H) diagnostic for G, also confirmed by CT slicing of the left side element of MOR 693 (I); splenial and prearticular in medial view, positioned in a reconstructed right lower jawof Saltriovenator (J). Maxillary or dentary tooth in labial (K) and apical (L) views; close-up of the distal carina and denticles in lingual (M) and distal (N) views. Left cervical rib (O) in craniolateral view; fragmentary right (P) and left (Q) dorsal ribs in craniolateral view.

Abbreviations as in text, ribs labeled as in Fig. 2 maps and caption. Scale bars equal two cm in (A)–(I), five cm in (J), one cm in (K), five mm in (L), one mm in (M)–(N), five cm in (O)–(Q). 

Photos by G. Bindellini, C. Dal Sasso, and M. Zilioli; drawing by C. Dal Sasso.

Systematic Paleontology

DINOSAURIA Owen, 1842

THEROPODA Marsh, 1881

NEOTHEROPODA Bakker, 1986

CERATOSAURIA Marsh, 1884

Saltriovenator zanellai gen. et sp. nov.

Etymology. Saltrio, Italian toponym name, from the locality where the holotype was found; venator, Latin word for hunter, it also refers to a type of Roman gladiator; zanellai, Latin genitive dedicated to Angelo Zanella, who discovered the fossil.

Holotype. MSNM V3664, very fragmentary and disarticulated skeleton (Figs. 4–13), represented by the following elements (among brackets, number of fragments per bone): partial right splenial (2) and right prearticular (1); cervical (1) and dorsal (9) ribs; furcula (1), incomplete left scapula (16), right scapular glenoid (1), partial right coracoid (5), fragmentary right sternal plate (2); right humerus (2), and proximal half of left humerus (2); ?right ?distal carpal, right metacarpal II, right phalanx II-1, fragmentary right phalanx II-2, and tip of the ?second right ungual phalanx; complete third right manual digit (phalanges III-1 to III-4); right distal tarsals III and IV, proximal portions of right metatarsals II, III, IV, and V(2).

Referred material. MSNM V3659, one maxillary or dentary tooth (Figs. 4 and 5).

Comments. As noted above, the discovery of all skeletal elements at the same time in a very restricted spot, the fact that all of them are of matching size, and that fragmentary and anatomically adjacent elements are of matching morphology, leave no doubt that all bones referred to the holotype come from the same individual. We prudentially exclude from the holotype the single tooth, which was found relatively associated to the bones but lacking its root and any jaw bone connection, thus raising the doubt that it might represent a shed tooth.

Type locality. “Salnova” quarry, Saltrio, Varese Province, Lombardy (northern Italy).

Horizon and Age. Saltrio Fm. (sensu Gnaccolini, 1964), bucklandi Zone, early Sinemurian (199.3–197.5 mya) (Ogg & Hinnov, 2012).

Diagnosis. Mid-to-large sized ceratosaurian characterized by the following unique combination of anatomical features (autapomorphies marked by asterisk—see also Fig. 4): humerus with deltopectoral crest protruding craniomedially for more than twice the shaft diameter, with distal lamina forming an abrupt corner (about 90°) with the proximodistal axis of the humeral shaft; metacarpal II with hypertrofied semicircular extensor lip protruding over the condylar level* and bordering dorsolaterally a very deep and wide extensor pit; phalanx II-1 with flexor palmar groove which is deep and narrow*, and bearing a distinct bump distal to the dorsal extensor process*; manual ungual III with prominent flexor tubercle which is distinctly separated from articular facet by a concave cleft.

 .....

Simplified evolutionary tree of predatory dinosaurs (theropods). Saltriovenator predates the massive meat-eating dinosaurs by over 25 million years: it is the oldest known ceratosaurian, and the world's largest predatory dinosaur from the Lower Jurassic. During the Jurassic, the three- fingered tetanuran theropods appeared, which gave rise to birds.

Conclusions

Saltriovenator zanellai gen. et sp. nov. is a new theropod dinosaur from the Lower Jurassic of Northern Italy. It represents the third named species of non-avian dinosaur from Italy, the first of Jurassic age. Saltriovenator shows a combination of ceratosaurian and tetanuran features, supporting close relationships between the two averostran lineages with the exclusion of coelophysoid-grade theropods. It also represents the first skeletal material supporting the occurrence of large and robustly-built predatory dinosaurs just at the aftermath of the Triassic–Jurassic boundary extinction events. Accordingly, the Italian ceratosaurian fills a stratigraphic and ecomorphological gap between the relatively more gracile coelophysoid-grade neotheropods (known from the Late Triassic to the Early Jurassic) and the large-bodied averostrans that occupied the majority of the apex predatory roles in the terrestrial ecosystems between the Middle Jurassic and the end of the Cretaceous.

The phylogenetic framework integrated with the new combination of features present in Saltriovenator dismisses the “II–III–IV homology pattern” in the interpretation of the tetanuran (and avian) hand, and suggests a complex process leading to the atrophied forelimb of later ceratosaurians. The evolution of a stocky and robust hand occurred in ceratosaurians before the relative shortening and the loss of predatory function: such a step-wise scenario raises intriguing perspectives on what adaptive and developmental factors led from a “Saltriovenator-like” condition to the aberrant condition present in Limusaurus and abelisaurids.

Cristiano Dal Sasso​, Simone Maganuco and Andrea Cau. 2018. The Oldest Ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, Sheds Light on the Evolution of the Three-fingered Hand of Birds.   PeerJ. 6:e5976.  DOI: 10.7717/peerj.5976

The oldest large-sized predatory dinosaur comes from the Italian Alps phys.org/news/2018-12-oldest-large-sized-predatory-dinosaur-italian.html via @physorg_com

Meet Saltriovenator: Oldest Known Big Predatory Dinosaur - Dead Things  bit.ly/2EuANJX

[Paleontology • 2017] Serikornis sungei • A New Jurassic Theropod from China Documents A Transitional Step in the Macrostructure of Feathers

Serikornis sungei
Lefèvre, Cau, Cincotta, Hu, Chinsamy, Escuillié & Godefroit, 2017

DOI: 10.1007/s00114-017-1496-y  

 Illustration: E. Willoughby EmilyWilloughby.com

theropoda.blogspot.com

  

Abstract

Genuine fossils with exquisitely preserved plumage from the Late Jurassic and Early Cretaceous of northeastern China have recently revealed that bird-like theropod dinosaurs had long pennaceous feathers along their hindlimbs and may have used their four wings to glide or fly. Thus, it has been postulated that early bird flight might initially have involved four wings (Xu et al. Nature 421:335–340, 2003; Hu et al. Nature 461:640–643, 2009; Han et al. Nat Commun 5:4382, 2014). Here, we describe Serikornis sungei gen. et sp. nov., a new feathered theropod from the Tiaojishan Fm (Late Jurassic) of Liaoning Province, China. Its skeletal morphology suggests a ground-dwelling ecology with no flying adaptations. Our phylogenetic analysis places Serikornis, together with other Late Jurassic paravians from China, as a basal paravians, outside the Eumaniraptora clade. The tail of Serikornis is covered proximally by filaments and distally by slender rectrices. Thin symmetrical remiges lacking barbules are attached along its forelimbs and elongate hindlimb feathers extend up to its toes, suggesting that hindlimb remiges evolved in ground-dwelling maniraptorans before being co-opted to an arboreal lifestyle or flight.

Keywords: Paraves, Birds, Feathers, Barbules, Jurassic, Flight evolution

 the basal bird Serikornis sungei sp. nov. [PMOL-AB00200] from the Middle-Late Jurassic of north-eastern China. 

Fig. 1 Photograph and drawing of the basal bird Serikornis sungei sp. nov. from the Middle-Late Jurassic of north-eastern China.
 a PMOL-AB00200 photograph. b Line drawing.

 Abbreviations: cev cervical vertebrae, co coracoids, cv caudal vertebrae, fu furcula, il ilium, is ischium, lf left femur, lfi left fibula, lh left humerus, lma left manus, lpes left pes, lr left radius, ls left scapula, lt left tibia, lu left ulna, pu pubis, ra radiale, rf right femur, rh right humerus, rma right manus, rpes right pes, rr right radius, rt right tibia, ru right ulna, sk skull

Systematic palaeontology

Theropoda Marsh, 1881

Maniraptora Gauthier, 1986

Paraves Sereno, 1997; Avialae Gauthier, 1986

Serikornis sungei gen. et sp. nov.

Etymology: Serikos, ancient Greek for silk, because the body is almost covered with plumulaceous-like feathers; Ornis, ancient Greek for bird; named in honour of Sun Ge, for his contribution to our knowledge of Jurassic and Cretaceous ecosystems in Asia.

Holotype: PMOL-AB00200 is a single complete articulated skeleton with associated integumentary structures preserved on a slab. The counterpart is missing, but most of the skeleton is preserved on the main slab.

Locality and horizon: PMOL-AB00200 was collected in the Tiaojishan Formation (Oxfordian, Upper Jurassic; Chu et al. 2016) from Daxishan village, Linglongta (Jianchang County, Liaoning Province, China).

Diagnosis: Serikornis is characterized by the following combination of characters (autapomorphies are marked with an asterisk): four anterior maxillary teeth twice as long as the others regarding the crown height*; coracoid tuber well-developed and laterally projected from the lateral margin of the coracoid and forming a subglenoid shelf along the caudoventral margin of the bone; the distal end of the lateral process of the coracoid is thicker than the proximal part and forms a ventral rounded bump; ventrodistal process of ischium narrow, hook-like, strongly deflected caudodorsally and set at the distal end of the ischium*; smooth ventral side of coracoid devoid of small pits.

....

Illustration: Emily Willoughby EmilyWilloughby.com

 facebook.com/photo.php?fbid=10100308789191064 

Ulysse Lefèvre, Andrea Cau, Aude Cincotta, Dongyu Hu, Anusuya Chinsamy, François Escuillié and Pascal Godefroit. 2017. A New Jurassic Theropod from China Documents A Transitional Step in the Macrostructure of Feathers. The Science of Nature. 104:74. DOI: 10.1007/s00114-017-1496-y 

facebook.com/photo.php?fbid=10100308789191064

facebook.com/photo.php?fbid=10213490546476049

EmilyWilloughby.com/gallery/paleoart/the-silky-serikornis

theropoda.blogspot.com/2017/08/serikornis-per-gli-amici-silky.html

    

[Paleontology • 2016] A Large Abelisaurid (Dinosauria, Theropoda) from Morocco and comments on the Cenomanian Theropods from North Africa

  Large Moroccan abelisaurid [Abelisauridae indet. femur OLPH 025]

Illustration: Davide Bonadonna

DOI: 10.7717/peerj.1754  & theropoda.blogspot.com

Abstract

We describe the partially preserved femur of a large-bodied theropod dinosaur from the Cenomanian “Kem Kem Compound Assemblage” (KKCA) of Morocco. The fossil is housed in the Museo Geologico e Paleontologico “Gaetano Giorgio Gemmellaro” in Palermo (Italy). The specimen is compared with the theropod fossil record from the KKCA and coeval assemblages from North Africa. The combination of a distally reclined head, a not prominent trochanteric shelf, distally placed lesser trochanter of stout, alariform shape, a stocky shaft with the fourth trochanter placed proximally, and rugose muscular insertion areas in the specimen distinguishes it from Carcharodontosaurus, Deltadromeus and Spinosaurus and supports referral to an abelisaurid. The estimated body size for the individual from which this femur was derived is comparable to Carnotaurus and Ekrixinatosaurus (up to 9 meters in length and 2 tons in body mass). This find confirms that abelisaurids had reached their largest body size in the “middle Cretaceous,” and that large abelisaurids coexisted with other giant theropods in Africa. We review the taxonomic status of the theropods from the Cenomanian of North Africa, and provisionally restrict the Linnean binomina Carcharodontosaurus iguidensis and Spinosaurus aegyptiacus to the type specimens. Based on comparisons among the theropod records from the Aptian-Cenomanian of South America and Africa, a partial explanation for the so-called “Stromer’s riddle” (namely, the coexistence of many large predatory dinosaurs in the “middle Cretaceous” record from North Africa) is offered in term of taphonomic artifacts among lineage records that were ecologically and environmentally non-overlapping. Although morphofunctional and stratigraphic evidence supports an ecological segregation between spinosaurids and the other lineages, the co-occurrence of abelisaurids and carcharodontosaurids, two groups showing several craniodental convergences that suggest direct resource competition, remains to be explained.

Systematic Palaeontology

Dinosauria Owen (1842).

Theropoda Marsh (1881).

Abelisauridae Bonaparte (1991).

Locality and age: Based on the registry of the OLPH, the specimen was collected nearby the Moroccan-Algerian boundary just south of Taouz (Errachidia Province, Meknès−Tafilalet Region), Morocco. Following Cavin et al. (2010), the age of this fossil is considered as Late Cretaceous (Cenomanian).

Material: OLPH 025, partial proximal portion of a right femur (Fig. 1).

Figure 1: Abelisauridae indet. femur OLPH 025.

(A) proximal view, (B) anterior view, (C) medial view, (D) posterior view, (E) lateral view, (F) distal view (not at same scale as other views). Scale bars, 5 cm.

Abbreviations: gt, greater trochanter; iMie, insertion for the M. iliofemoralis externus; fn, femoral neck; s, shallow sulcus.   DOI: 10.7717/peerj.1754

Conclusions

The taxonomy and inclusiveness of the theropod clades from the “middle” Cretaceous of North Africa is complex and problematic. Since Stromer (1931) and Stromer (1934) the minimum number of taxa recovered from these fossil associations has been considered controversial, in particular due to the fragmentary nature of most of the specimens found. Stromer himself (1934) was aware of this as one of the main problems in North African dinosaur palaeontology. Several factors, both biological and geological, may bias the taxonomic composition of the North African theropod faunas. Most North African units are poorly constrained stratigraphically (see Cavin et al., 2010; Fanti et al., 2014), thus preventing detailed correlations between the various localities. For example, the age of the KKCA has been alternatively placed between the Aptian and the Cenomanian (Russell, 1996; Cavin et al., 2010), and both number of and relationships among the units represented by that assemblage remain controversial (Sereno et al., 1996; Cavin et al., 2010). The temporal extent of these assemblages is uncertain, possibly spanning several million years (Cavin et al., 2010). Therefore, the application of biological (neontological) “rules,” based on ecological models and data from modern ecosystems (in order to constrain the number of carnivorous taxa included in a fossil assemblage) is often not adequately justified or not testable. This is particularly problematic for fossil assemblages, like the KKCA, that lack present-day analogues and where an unusually unbalanced ecological web has been suggested (e.g., Läng et al., 2013). Since the co-occurrence in the same North African theropod associations of distinct species belonging to the same clade has been documented (e.g., spinosaurids, Fanti et al., 2014; Hendrickx, Mateus & Buffetaut, 2016; carcharodontosaurids, Cau, Dalla Vecchia & Fabbri, 2012; Cau, Dalla Vecchia & Fabbri, 2013), the referral of all isolated elements of one lineage to a single species cannot be justified. Furthermore, the referral of isolated and non-overlapping material to the same species is a phylogenetic hypothesis itself that needs to be explicitly tested by numerical analyses. In absence of positive evidence supporting the referral of such material to a particular species, the inclusion of non-overlapping elements into a single taxon may led to the creation of a potential chimera, with unpredictable effects on the phylogenetic and palaeoecological interpretation of these faunas.

We have described the fragmentary femur of a large-bodied theropod from the “Kem Kem Compound Assemblage” of Morocco. The specimen lacks tetanuran synapomorphies and is referred to Abelisauridae as it shares the overall morphology of the femora of ceratosaurians and the stocky robust proportions of some Late Cretaceous abelisaurids (e.g., Ekrixinatosaurus, Majungasaurus, Carrano, 2007; Juarez-Valieri, Porfiri & Calvo, 2011). The large size of the preserved femur suggests an individual comparable in body size with the type specimens of Carnotaurus sastrei and Ekrixinatosaurus novasi, both estimated to reach 9 meters in length and approaching two tons in body mass (Juarez-Valieri, Porfiri & Calvo, 2011). This discovery further supports that abelisaurids had evolved their largest size no later than the “mid-Cretaceous” (Smith et al., 2010; Juarez-Valieri, Porfiri & Calvo, 2011) and that abelisaurids and carcharodontosaurids co-existed and ecologically overlapped in both North Africa and South America during the Aptian-Turonian. Based on comparison with other “middle Cretaceous” units (Juarez-Valieri, Porfiri & Calvo, 2011; Fanti et al., 2014), we suggest that the co-occurrence of spinosaurids and other large theropods (abelisaurids and carcharodontosaurids) in the KKCA may be mainly an artefact due to poor stratigraphic resolution rather than genuine evidence of  ecological and environmental overlap. Given the convergent evolution of several craniodental features among abelisaurids and carcharodontosaurids (Lamanna, Martinez & Smith, 2002; Sampson & Witmer, 2007; Carrano & Sampson, 2008; Cau, Dalla Vecchia & Fabbri, 2013), suggesting similar ecological adaptations in these clades, how these apparently competing groups co-existed for at least 30 million years in both Africa and South America remains to be resolved.

Alfio Alessandro Chiarenza and Andrea Cau. 2016. A Large Abelisaurid (Dinosauria, Theropoda) from Morocco and comments on the Cenomanian Theropods from North Africa.  PeerJ. 4:e1754; DOI: 10.7717/peerj.1754

Fossil find reveals just how big carnivorous dinosaur may have grown

 http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_29-2-2016-9-34-57

[Paleontology • 2013] Tataouinea hannibalis • A new sauropod dinosaur from the Early Cretaceous of Tunisia with an extreme avian-like pneumatization

Tataouinea hannibalis

Fanti, Cau, Hassine & Contessi 2013

Art by D. Bonadonna

Recent interpretations of the postcranial anatomy of sauropod dinosaurs differ about pneumatic features supporting an avian-like ventilatory system; the most conservative workers reject most postcranial pneumatizations as being unambiguous evidence of abdominal air sacs. Here we describe the first articulated dinosaur skeleton from Tunisia and refer it to a new rebbachisaurid sauropod, Tataouinea hannibalis gen. et sp. nov. The Tunisian specimen shows a complex pattern of caudosacral and pelvic pneumatization—including the first report of an ischial pneumatic foramen among Dinosauria—strongly supporting the presence of abdominal air sacs. Character optimization among Rebbachisauridae indicates that in the caudal vertebrae, pneumatization of the neural arches preceded that of the centra; in the pelvis, pneumatization of the bones adjacent to the sacrum preceded that of more distal elements. Tataouinea was more closely related to European nigersaurines than to otherwise Gondwanan rebbachisaurids; this supports an Afro-European route for rebbachisaurid dispersal.

Subject terms: Biological sciences, Evolution, Palaeontology

Fanti F., Cau A., Hassine M., Contessi M. 2013. A new sauropod dinosaur from the Early Cretaceous of Tunisia with an extreme avian-like pneumatization. Nature Communications. 4 (2080): 1–7. DOI: 10.1038/ncomms3080

http://theropoda.blogspot.it/2013/07/tataouinea-hannibalis-fanti-cau-hassine.html