[Paleontology • 2018] Large-sized Theropod Spinosaurus: An Important Component of the Carnivorous Dinosaur Fauna in southern Continents During the Cretaceous

Semi-aquatic paleoenvironmental reconstruction of Spinosaurus dinosaur during early Late Cretaceous:
 (A) Spinosaurus; (B) Mawsonia coelacanth fishes

in Candeiro, Gil & de Castro, 2018. 

 DOI: 10.1051/bsgf/2018010 

 (drawing Luciano Vidal)

Abstract 

The Early Cretaceous of North Africa has Spinosaurinae dinosaur remains such as Spinosaurus recorded in Algeria (Guir Basin, Kem Kem beds), Egypt (Bahariya Formation), Morocco (Kem Kem beds), and Tunisia (Ain El Guettar Formation). Until now, three possible Spinosaurus species were identified: Spinosaurus aegyptiacus, Spinosaurus sp. and Spinosaurus “B”. The occurrence of this genus in the Albian-Cenomanian rocks of Africa suggests that the temporal and geographic distribution of these spinosaurines is the largest one among all genera and species of megapredators from the middle Cretaceous of Africa. The fossil record of Spinosaurus from the Albian to the Cenomanian shows a 20 million year persistence of this genus in Gondwanan ecosystems.

Keywords: theropod dinosaur, distribution, Early Cretaceous, Africa

Fig. 3 Most complete Spinosaurus species skulls from early Late Cretaceous formations from Northern Africa.
 Spinosaurus aegyptiacus (from Stromer, 1915), BSP 1912 – dentary, A in lateral and B in dorsal views.
Spinosaurus cf. aegyptiacus (from Buffetaut and Ouaja, 2002), BM231 – rostral part of left dentary, C, in lateral and in D dorsal views.
 Spinosaurus marrocanus (nomen dubium) (Taquet and Russell, 1998) MNHM SAM 124 – left maxilary, E in lateral and F dorsal views.
Spinosaurus cf. S. aegyptiacus (from Dal Sasso et al., 2005) MSNM V4047 – left maxilary, G in lateral in dorsal view.

Fig. 5. Semi-aquatic paleoenvironmental reconstruction of Spinosaurus dinosaur during early Late Cretaceous: (A) Spinosaurus; (B) Mawsonia coelacanth fishes; (C) Araripemys turtle (drawing Luciano Vidal).

 Remarks: 

The middle Cretaceous strata of North Africa preserved an important record of the theropod Spinosaurus. Although their fossil remains are usually fragmented, most specimens show diagnostic characters of the genus Spinosaurus that are especially present in their conical and non-serrated teeth. The fossil record of this genus in North Africa shows a restricted geographic distribution between the Albian and the Cenomanian periods. Yet, when we consider their temporal distribution, it suggests that Spinosaurus had a significant geological history of nearly 20 million years, a lifespan unknown for other African megapredators species (e.g., Carcharodontosaurus – 18.5 mya [Candeiro et al., 2018]). The geological evidences indicate that Africa was an island during the main period of occurrence of this genus. The faunal composition of the spinosaurinae that inhabited the eastern coast of Africa is broadly comparable with the Cenomanian fossil records from western Africa, supporting the relative homogeneous composition of the taxon in these areas during this period. Additional studies and future field prospections in other localities could eventually reveal a wider distribution of this genus in other regions of Africa (e.g., Niger, Sudan) or even in western Europe and northern South America.

Carlos Roberto A. Candeiro, Lívia Motta Gil and Pedro Ernesto Pontes de Castro. 2018. Large-sized Theropod Spinosaurus: An Important Component of the Carnivorous Dinosaur Fauna in southern Continents During the Cretaceous. Bulletin de la Société Géologique de France. 189 (4-6): 15.  DOI: 10.1051/bsgf/2018010

Résumé – Spinosaurus (théropode de grande taille) : une composante importante de la faune de dinosaures carnivores des continents méridionaux au cours du Crétacé. Le Crétacé inférieur d’Afrique du Nord renferme des restes de dinosaures spinosaurinés, tels que Spinosaurus répertorié en Algérie (Bassin du Guir, Kem Kem beds), en Égypte (Formation Bahariya), au Maroc (Kem Kem beds) et en Tunisie (Formation Ain El Guettar). Jusqu’à ce jour, trois espèces de spinosaure sont reconnues : Spinosaurus aegyptiacus, Spinosaurus sp. et Spinosaurus “B”. La présence de ce genre dans les terrains albocénomaniens d’Afrique suggère que la répartition temporelle et géographique de ces spinosaurinés est la plus étendue de tous les genres et espèces de méga-prédateurs du Crétacé moyen d’Afrique. Le registre fossile de Spinosaurus, depuis l’Albien jusqu’au Cénomanien, indique une présence de 20 millions d’années pour ce genre dans les écosystèmes gondwaniens. 

Mots clés : théropode dinosaure / distribution / Crétacé inférieur / Afrique

[Paleontology • 2018] The Smallest Biggest Theropod Dinosaur: A Tiny Pedal Ungual of A Juvenile Spinosaurus from the Cretaceous of Morocco

Size-comparison of selected Spinosaurus individuals from the Kem Kem Beds: MSNM V6894 (B, this paper), the neotype FSAC-KK18888 (C) and the largest known individual MSNM V4047 (D), compared with Homo (1.75 m tall). 

in Maganuco​​ & Dal Sasso​, 2018.   

DOI: 10.7717/peerj.4785 

Abstract

We describe a nearly complete pedal ungual phalanx, discovered in the Kem Kem Beds (Cenomanian) of Tafilalt region, south-eastern Morocco. The bone is symmetric, pointed, low, elongate, and almost flat ventrally in lateral aspect. This peculiar morphology allows to refer the specimen to the smallest known individual of the genus Spinosaurus. The bone belongs to an early juvenile individual and it is proportionally identical to the ungual of the third digit of a large partial skeleton recently found, suggesting an isometric growth for this part of the pes and the retention of peculiar locomotor adaptations—such as traversing soft substrates or paddling—during the entire lifespan.

Figure 3: Anatomical and size comparisons. Specimen MSNM V6894 in dorsal view,
compared to a cast of the right ungual III-4 of specimen FSAC-KK18888 (A). 

Size-comparison of selected Spinosaurus individuals from the Kem Kem Beds: MSNM V6894 (B, this paper), the neotype FSAC-KK18888 (C) and the largest known individual MSNM V4047 (D), compared with Homo (1.75 m tall). 

Drawing by Marco Auditore and Prehistoric Minds, used with their permission.
 Scale bar equals 20 mm in A. Photos by M. Zilioli and C. Dal Sasso, used with their permission.

Systematic Palaeontology

DINOSAURIA Owen, 1842

THEROPODA Marsh, 1881

SPINOSAURIDAE Stromer, 1915

SPINOSAURUS Stromer, 1915

cf. Spinosaurus aegyptiacus Stromer, 1915

MSNM V6894 strongly resembles the pedal ungual phalanges associated to diagnosable skeletal remains of specimen FSAC-KK18888, described by Ibrahim et al. (2014) and defined as the neotype of S. aegyptiacus. MSNM V6894 shares with FSAC-KK18888 the following diagnostic characters: pedal unguals with flat plantar surface; pedal unguals broader than deep with length almost four times of the proximal depth. The overall morphology, proportions, and pattern of furrows are also very similar (see “Description and comparisons”). Following Ibrahim et al. (2014) we refer the ungual MSNM V6894 to cf. S. aegyptiacus. The variability found in cervicodorsal vertebrae (Evers et al., 2015) and quadrates (Hendrickx, Mateus & Buffetaut, 2016) might indicate a higher diversity among the spinosaurid material from the Albian–Cenomanian of North Africa than previously recognized. This proportional and morphological diversity may be related to individual variability or sexual dimorphism, or it could be above the species level. However, taking into account the low number of the known specimens, their low degree of completeness, their apparently strict taxonomic affinities, their occurrence in the same strata (or, more often, their uncertain stratigraphic provenance), and all the difficulties and controversies in investigating these aspects and, ultimately, in defining a species in palaeontology, we prefer to regard all the spinosaurid material (including pedal unguals) from the Kem Kem Beds as belonging to cf. S. aegyptiacus, pending more complete, articulated remains and reliable geological data. Further comments on this topic are beyond the purpose of this paper.

Locality: MSNM V6894 comes from some kilometers south of Erfoud, between the villages of Taouz and Begaa, Errachidia Province, Morocco (Fig. 1).

Horizon: Kem Kem Beds, Cenomanian, Upper Cretaceous (Sereno et al., 1996). The specimen was collected by G. Pasini (2008, personal communication) together with rostral teeth of the Aptian–Cenomanian elasmobranch Onchopristis sp. (Rage & Cappetta, 2002; Russell, 1996).

Conclusion

The specimen described here improves the knowledge about the appendicular skeleton of the spinosaurid theropods from the Kem Kem Beds (Late Cretaceous of Morocco) published by Ibrahim et al. (2014).

The new material indicates that the pedal ungual phalanges of Spinosaurus grew with isometry and it documents the smallest individual referable to Spinosaurus, a genus/taxon usually indicated as the longest if not the largest theropod dinosaur (Dal Sasso et al., 2005). The specimen FSAC-KK18888, with an estimated body length of 11 m, has an ungual phalanx of digit III that is 130 mm long. Assuming isometry—although isometrical scaling of the other parts of the spinosaur hind limb skeleton shown in Fig. 3 must be considered as tentative—the 21 mm long ungual MSNM V6894 would pertain to an early juvenile individual, 1.78 m long (Figs. 3B–3D), that is half the estimated length of the smallest Spinosaurus published up to date, represented by the isolated quadrate MNHN KK374 (Hendrickx, Mateus & Buffetaut, 2016).

According to Ibrahim et al. (2014), the unguals in Spinosaurus are reminiscent of the flattened pedal unguals of shorebirds that do not perch (Manegold, 2006), and the whole foot may have been adapted to traversing soft substrates or webbed for paddling. We agree with this hypothesis although it needs to be tested in the future based on more complete fossil remains and biomechanical analyses. The isolated tiny ungual here referred to a small, early juvenile of Spinosaurus indicates that the pes had the same locomotor adaptations observed in large individuals, that were probably achieved early in ontogeny and retained for the entire lifespan.

Simone Maganuco​​ and Cristiano Dal Sasso​. 2018. The Smallest Biggest Theropod Dinosaur: A Tiny Pedal Ungual of A Juvenile Spinosaurus from the Cretaceous of Morocco.   PeerJ. 6:e4785.  DOI: 10.7717/peerj.4785

   

[Paleontology • 2018] Semi-aquatic Adaptations in A Spinosaur from the Lower Cretaceous of Brazil

A Spinosaurinae at the Aptian-Albian lagunar/shallow marine environment of the Romualdo Formation, Araripe Basin, NE Brazil.

in Aureliano, Ghilardi, Buck, et al., 2018. 

DOI: 10.1016/j.cretres.2018.04.024 

Illustration by Julio Lacerda.

Highlights

• Spinosaur histology is here described for the first time.

• Extreme bone compactness (osteosclerosis) was present in Brazilian Spinosaurinae.

• These modifications appeared millions of years before the Moroccan Spinosaurus.

• One of the largest spinosaur specimens from the Early Cretaceous of South America.

Abstract

Spinosaurinae are known to have a strong relationship with aquatic environments, involving several anatomical adaptations. Nonetheless, this group of theropods remains enigmatic, due to the relative incompleteness of its fossil record. A large partial tibia from the Aptian-Albian Romualdo Formation, Northeast Brazil, is herein described through anatomical comparisons and paleohistological analyzes. It features characteristics previously only observed in Spinosaurus aegyptiacus, which includes a reduced fibular crest and an osteosclerotic condition. The later, a character supported as correlated with semi-aquatic habits in many limbed vertebrates. The results presented here support high bone compactness being already present in Brazilian Spinosaurinae millions of years before the Moroccan Spinosaurus. Furthermore, histological analyses demonstrate the Romualdo Formation specimen was a young subadult still growing fast by the time of its death, and suggests Araripe Basin Spinosaurinae could have grown larger than previously thought. This work contributes to a better paleobiological and ecological understanding of South American spinosaurs, and helps fill a gap in the macroevolutionary comprehension of Spinosaurinae. Ultimately, it also contributes to further advancing the paleoecological characterization of the Romualdo Formation.

Keywords: Paleohistology; Araripe basin; Theropoda; Megalosauroidea; Spinosaurinae

Systematic paleontology

Dinosauria Owen, 1842

Theropoda Marsh, 1882

Tetanurae Gauthier, 1986

Megalosauroidea Fitzinger, 1843

Spinosauridae Stromer 1915

Spinosaurinae Stromer, 1915

gen. et. sp. indet.

Referred material: LPP-PV-0042, a fragmentary tibia.

Locality and horizon: Exact geological and geographical provenance is unknown, but the fossil was collected in the Araripe area, Northeast Brazil. Outcrops of the Lower Cretaceous Santana Group (Araripe Basin) are worldwide known for providing well-preserved fossils and are located in the Araripe region. 

Fig. 6. 1. Spinosaurinae remains currently recovered from the Romualdo Formation, Araripe Basin, Brazil. Not to scale.
 A, USP GP/2T-5, holotype of Angaturama limai ( Kellner & Campos, 1996), fragmentary anterior tip of skull.
B, SMNS 58022, holotype of Irritator challengeri (Sues et al., 2002) (originally mistakenly identified as a maniraptor by Martill et al., 1996), partial posterior portion of skull and mandible.
C, MN 4743-V, incomplete indeterminate spinosaur sacral and caudal vertebrae series (S3, S4, S5, C1, C2. C3, C4, C4, C6) (Bittencourt & Kellner, 2004).
D, MN 7021-V, indeterminate spinosaur rib (Machado & Kellner, 2007). E, MN4819-V, incomplete indeterminate spinosaur pubis, pelvis, dorsal, sacral and caudal vertebrae (d, S1, S2, S3, S4, S5, C1), incomplete indeterminate spinosaur right manus, fragmentary right tibia and femur ( Machado et al., 2008; Machado and Kellner, 2009 ; Machado, 2010).
 F, LPP-PV-0042, Spinosaurinae indet. metaphysis of left tibia described in this work. Skeletal reconstruction made by Tito Aureliano, based on the work by Scott Hartman and Marcos Sales. 

2. Romualdo Spinosaurinae specimens to scale. A, Angaturama USP GP/2T (∼8.3 m, on the reconstruction by Sales & Schultz, 2017). B, Irritator SMNS 58022 (∼6.5 m, from the reconstruction by Sales & Schultz, 2017). C, Spinosaurinae indet. MN4819-V (∼5.9 m; Machado et al., 2008). D, Spinosaurinae indet. LPP-PV-0042 (∼10 m; this work). Scale bar in 7.2 is 1 m. 

Fig. 8. Reconstruction of a Spinosaurinae at the Aptian-Albian lagunar/shallow marine environment of the Romualdo Formation, Araripe Basin, NE Brazil. 

Illustration by Julio Lacerda.

Fig. 7. Inferred food web of the Aptian-Albian Romualdo Formation, Northeast Brazil. Vertebrate silhouettes are highlighted in black. Trophic relations are represented by arrows, of which solid bold red represent ecological interactions with direct fossil evidence from Romualdo Formation; solid black indicate putative trophic interactions with general theoretical support; and dashed grey represent weak or uncertain but plausible trophic links.
1, Spinosaurinae; 2, small to medium sized terrestrial theropods; 3, pterosaurs; 4, semi-aquatic crocodyliforms; 5, terrestrial omnivorous crocodyliforms; 6, semi-aquatic chelonians; 7, large fishes; 8, small fishes; 9, plants; 10, macroinvertebrates; 11, plankton. See Text S1 in the Supplementary material for list of references. Spinosaurinae silhouette by Tito Aureliano. Other silhouettes from Phylopic (http://phylopic.org/), courtesy of Almandine (vectorized by T. Michael Keesey), FunkMonk (adapted), Hans Hillewaert, John Conway, Melissa Broussard, Nobu Tamura (vectorized by T. Michael Keesey), Olegivvit, Robert Gay and Sergio A. Muñoz-Gómez.  

Conclusion: 

The Romualdo Formation specimen LPP-PV-0042 comprises a fragmentary tibia with a reduced fibular crest and osteosclerotic histology previously only observed in Spinosaurus aegyptiacus, supporting that this unique feature was already present in Brazilian Spinosaurinae (basal Spinosaurinae) during the Aptian-Albian time, at least 10 myr before the Moroccan Spinosaurus.

Histological analyses suggest LPP-PV-0042 was a young, fast growing subadult and also that the bone microstructure varies a lot across the cross-section, probably due to areas of muscle insertion. The latter observation suggests that caution is needed when describing bone histology of dinosaurs, since only one slice from the shaft is not always representative of the entire histology of the bone.

Furthermore, the current specimen represents one of the largest spinosaurs from this unit so far (∼10 m in reconstructed TL). It was larger than the Irritator holotype and possibly larger than Angaturama holotype as well. Considering the subadult status inferred from its histology, the referred individual would have grown even larger.

The Romualdo paleoenvironment could support large predators with semi-aquatic habits due to its high productivity and diversity of aquatic species as an ecotone. Spinosaurinae from Romualdo Formation probable occupied the position of apex predators different.

Thus, the skeletal element LPP-PV-0042 from the Romualdo Formation, although fragmentary, has provided much information about Brazilian Spinosaurinae paleobiology and ecology. Moreover, it gives new insight into the evolution of semi-aquatic adaptations in this group, revealing the need to investigate other taxa within the clade and expand the search for more spinosaur fossils.

  

Tito Aureliano, Aline M. Ghilardi, Pedro V. Buck, Matteo Fabbri, Adun Samathi, Rafael Delcourt, Marcelo A. Fernandes and Martin Sander. 2018. Semi-aquatic Adaptations in A Spinosaur from the Lower Cretaceous of Brazil. Cretaceous Research. In Press.  DOI: 10.1016/j.cretres.2018.04.024

 twitter.com/AlineGhilardi/status/992177606933000192

 twitter.com/AlineGhilardi/status/992152367633240065

Dense Bones and Other Aquatic Adaptations in Spinosaurs  https://blog.everythingdinosaur.co.uk/blog/_archives/2018/05/06/dense-bones-and-other-aquatic-adaptations-in-spinosaurs.html

[Paleontology • 2017] Spinosaur Taxonomy and Evolution of Craniodental Features: Evidence from Brazil

Spinosaurid cranial remains from Brazil.

Sales & Schultz, 2017 

DOI: 10.1371/journal.pone.0187070 

Abstract

Fossil sites from Brazil have yielded specimens of spinosaurid theropods, among which the most informative include the cranial remains of Irritator, Angaturama, and Oxalaia. In this work some of their craniodental features are reinterpreted, providing new data for taxonomic and evolutionary issues concerning this particular clade of dinosaurs. The mesial-most tooth of the left maxilla of the holotype of Irritator is regarded as representing the third tooth position, which is also preserved in the holotype of Angaturama. Thus, both specimens cannot belong to the same individual, contrary to previous assumptions, although they could have been the same taxon. In addition, the position of the external nares of Irritator is more comparable to those of Baryonyx and Suchomimus instead of other spinosaurine spinosaurids. In fact, with regards to some craniodental features, Brazilian taxa represent intermediate conditions between Baryonychinae and Spinosaurinae. Such a scenario is corroborated by our cladistic results, which also leave open the possibility of the former subfamily being non-monophyletic. Furthermore, the differences between spinosaurids regarding the position and size of the external nares might be related to distinct feeding habits and degrees of reliance on olfaction. Other issues concerning the evolution and taxonomy of Spinosauridae require descriptions of additional material for their clarification.

Fig 1. Map of northeastern Brazil showing the location of the Araripe and São Luís-Grajaú basins. The (likely) provenance of the holotypes of local spinosaurid taxa is indicated. Modified from Bittencourt and Lange. 

Fig 2. Specimen SMNS 58022, holotype of Irritator challengeri.

A, Left lateral view. B, Right lateral view. The abbreviation for the third tooth of the left maxilla follows Hendrickx et al. [2015].

 Additional abbreviations: ao.f, antorbital fenestra; c.c, crista cranii; e.n, external naris; m, maxilla; m.r, mandibular ramus; n, nasal; n.c, nasal sagittal crest; n.p, nasal process; o, orbit; pm, premaxilla; s, stapes.

Fig 11. Spinosaurid cranial remains from Brazil.

 A, Reconstruction of specimen SMNS 58022, the holotype of Irritator challengeri. B, Specimen USP GP/2T-5, the holotype of Angaturama limai. C, Specimen MN 6117-V, the holotype of Oxalaia quilombensis.

The fragmentary maxilla (MN 6119-V) tentatively referred to O. quilombensis was not included. A is modified from Sues et al. [2002].

Final remarks

Spinosaurid dinosaurs have been surrounded by an enigmatic atmosphere due to their bizarre anatomy and morphology as well as the fragmentary nature of most collected specimens. The tragic loss of the holotype of Spinosaurus aegyptiacus also contributed to this condition. Despite being incomplete, spinosaurid cranial remains from Brazil are informative in multiple ways and help fill in some gaps in the knowledge on these theropods. The reinterpretation of certain craniodental features supports, for example, the distinction between Irritator and Angaturama at least at the individual level, and our cladistic results indicate the latter taxon and Oxalaia as successive outgroups of MSNM V4047. In addition, the evolution of spinosaurid craniodental features is likely related to different trends towards semiaquatic and/or piscivorous habits. These trends might have had a major impact on the position and size of the external nares, suggesting the reduction of the importance of olfaction in relation to other senses during foraging. However, other issues remain more disputable, such as the possible non-monophyly of Baryonychinae, the possible synonymy between the Araripe spinosaurids, and the sequence of morphological changes during the evolutionary history of Spinosauridae. Further study is needed to address these issues, including the formal description of additional cranial and postcranial remains. In this sense, although African materials are usually the focus of most investigations, Brazilian specimens play an important role in discussions concerning the evolution and paleobiology of Spinosauridae. This statement is clearly corroborated by new findings of these dinosaurs in understudied fossil sites.

Marcos A. F. Sales and Cesar L. Schultz. 2017. Spinosaur Taxonomy and Evolution of Craniodental Features: Evidence from Brazil. PLoS ONE. 12(11); e0187070. DOI: 10.1371/journal.pone.0187070

[Paleontology • 2016] The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clade

Fig 5. Reconstruction of the terrestrial paleoenvironmental setting of the Sao Khua Formation, Northeastern Thailand.
In the center, a generalized spinosaurid feeds on a sauropod. This trophic relationship is hypothesized based on isolated tooth crowns found in association with a sauropod skeleton [Buffetaut & Suteethorn, 1999]. In the background, a small pack of the ornithomimosaur theropod Kinnareemimus. Both sauropods and ornithomimosaurs (as part of the “herbivorous” theropods) were found to be positively associated with terrestrial paleoenvironments by Butler and Barrett (2008)

Illustration: Renata Cunha  DOI: 10.1371/journal.pone.0147031

Abstract

The view of spinosaurs as dinosaurs of semi-aquatic habits and strongly associated with marginal and coastal habitats are deeply rooted in both scientific and popular knowledge, but it was never statistically tested. Inspired by a previous analysis of other dinosaur clades and major paleoenvironmental categories, here we present our own statistical evaluation of the association between coastal and terrestrial paleoenvironments and spinosaurids, along with other two theropod taxa: abelisaurids and carcharodontosaurids. We also included a taphonomic perspective and classified the occurrences in categories related to potential biases in order to better address our interpretations. Our main results can be summarized as follows: 1) the taxon with the largest amount of statistical evidence showing it positively associated to coastal paleoenvironments is Spinosauridae; 2) abelisaurids and carcharodontosaurids had more statistical evidence showing them positively associated with terrestrial paleoenvironments; 3) it is likely that spinosaurids also occupied spatially inland areas in a way somehow comparable at least to carcharodontosaurids; 4) abelisaurids may have been more common than the other two taxa in inland habitats.

Fig 4. Schematic illustration of the spatial distribution of Abelisauridae, Carcharodontosauridae, and Spinosauridae throughout coastal and terrestrial paleoenvironments.
 Spinosaurids seem to have been natural inhabitants of coastal settings, while terrestrial and more inland habitats were shared by them and both abelisaurids and carcharodontosaurids. Note that the number of body icons (not to scale) does not reflect perfectly the relative abundance of these taxa within each paleoenvironment.

DOI: 10.1371/journal.pone.0147031

Marcos A. F. Sales , Marcel B. Lacerda, Bruno L. D. Horn, Isabel A. P. de Oliveira and Cesar L. Schultz. 2016. The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clades.
PLoS ONE. DOI: 10.1371/journal.pone.0147031

Buffetaut E and Suteethorn V. 1999. The dinosaur fauna of the Sao Khua Formation of Thailand and the beginning of the Cretaceous radiation of dinosaurs in Asia. Palaeogeogr Palaeoclimatol Palaeoecol. 150: 13–23. doi: 10.1016/s0031-0182(99)00004-8

Butler RJ and Barrett PM. 2008. Palaeoenvironmental controls on the distribution of Cretaceous herbivorous dinosaurs. Naturwissenschaften. 95: 1027–32. doi: 10.1007/s00114-008-0417-5.

[Paleontology • 2016] Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa

two species of Spinosaurinae, and ascribed to Spinosaurus aegyptiacus and ?Sigilmassasaurus brevicollis from the Cenomanian of North Africa

Illustration: S. Krasovskiy atrox1.deviantart.com DOI:  10.1371/journal.pone.0144695

Abstract

Six quadrate bones, of which two almost certainly come from the Kem Kem beds (Cenomanian, Upper Cretaceous) of south-eastern Morocco, are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, geometric morphometric, and phylogenetic morphometric analyses. Their morphology indicates two morphotypes evidencing the presence of two spinosaurine taxa ascribed to Spinosaurus aegyptiacus and ?Sigilmassasaurus brevicollis in the Cenomanian of North Africa, casting doubt on the accuracy of some recent skeletal reconstructions which may be based on elements from several distinct species. Morphofunctional analysis of the mandibular articulation of the quadrate has shown that the jaw mechanics was peculiar in Spinosauridae. In mature spinosaurids, the posterior parts of the two mandibular rami displaced laterally when the jaw was depressed due to a lateromedially oriented intercondylar sulcus of the quadrate. Such lateral movement of the mandibular ramus was possible due to a movable mandibular symphysis in spinosaurids, allowing the pharynx to be widened. Similar jaw mechanics also occur in some pterosaurs and living pelecanids which are both adapted to capture and swallow large prey items. Spinosauridae, which were engaged, at least partially, in a piscivorous lifestyle, were able to consume large fish and may have occasionally fed on other prey such as pterosaurs and juvenile dinosaurs.

Systematic Paleontology

Dinosauria Owen, 1842 

Saurischia Seeley, 1887 

Theropoda Marsh, 1881 

Tetanurae Gauthier, 1986 

Megalosauroidea (Fitzinger, 1843) Walker 1964 

Spinosauridae Stromer, 1915 

Spinosaurinae (Stromer, 1915) Sereno et al., 1998 

Description: The six isolated quadrates from the Kem Kem beds of Morocco clearly belong to two morphotypes (Figs 2–4) based on the size and outline of the quadrate foramen, shape of the mandibular articulation, and outline, surface, and orientation of the quadratojugal contacts. Measurements taken on each quadrate (Fig 5A–5D) are provided in Table 1.

Spinosaurus Stromer, 1915 

Spinosaurus aegyptiacus Stromer, 1915 

?Sigilmassasaurus Russel, 1996 

?Sigilmassasaurus brevicollis Russel, 1996 

Spinosaurus aegyptiacus and ?Sigilmassasaurus brevicollis

by S. Krasovskiy atrox1.deviantart.com

Conclusion

The description and identification of six isolated quadrates, among which two most probably come from the Kem Kem beds of Morocco, provide additional information on the Cenomanian dinosaur fauna of North Africa. Based on cladistic, geometric morphometric, and phylogenetic morphometric analyses, two morphotypes have been successfully identified as belonging to two species of Spinosaurinae, and ascribed to Spinosaurus aegyptiacus and ?Sigilmassasaurus brevicollis. This study provides the first convincing evidence of two spinosaurine taxa in the Cenomanian of North Africa based on cranial material, casting doubt on the recent reconstruction of a quadrupedal Spinosaurus which may be based on individuals belonging to two different species of Spinosaurinae.

Ontogenetic changes occurring in the spinosaurid quadrates include the suture of the quadrate and quadratojugal, delimitation of the mandibular condyles and squamosal capitulum, and development of a ventral projection of the dorsal quadratojugal contact and a second quadrate ridge ventral to the quadrate head. Based on the quadrate proportions and estimated skull length of Baryonyx and Spinosaurus, quadrates of mature individuals from Morocco belong to animals with a skull length of no more than 120 cm. This suggests that very large forms of Spinosaurus may have been rare in the Kem Kem assemblages.

Morphofunctional analysis of the spinosaurid quadrates has revealed peculiar jaw mechanics in these specialized theropods. An helicoidal and strongly lateromedially oriented joint of the jaw articulation allowed the lateral displacement of the mandibular ramus when the lower jaw was depressed. This lateral movement of the ramus was possible due to a movable mandibular symphysis as the dentaries were joined by connective tissues, and allowed the pharynx to be widened. A similar jaw articulation was convergently present in pterosaurs and particularly pelecanids which also have a mandibular symphysis restricted to the anterior extremity of the mandible. Spinosauridae, which are considered to be semi-aquatic and partially piscivorous animals, were able to swallow large prey such as fish in the same way as pelecanids.

  

Fig 15. Jaw mechanics in the spinosaurid Spinosaurus.
A–D, Mandibular articulation; and F, G, skull in A, C, F–G, lateral; and B, D, anterior views; when A–B, F, the mouth is closed; and C–D, G, fully open, illustrating the lateral movement (in red) of the mandibular ramus for a 45° rotation of the lower jaw (courtesy of Jaime A. Headden); E, skeletal reconstruction of Spinosaurus aegyptiacus by Ibrahim et al. [22]) in swimming position in lateral view with a human (1.8 m) as a scale (modified from Ibrahim et al. [22]). This model is based on spinosaurid cranial and postcranial remains (colored in red) from the Albian-Cenomanian of Northern Africa which possibly belong to two spinosaurine taxa (see also Evers et al. [27]); H, reconstruction of a semi-aquatic Spinosaurus in fishing position (i.e., jaws wide open) in anterolateral view (courtesy of Jason Poole).

Abbreviations: an, angular; ar, articular; d, dentary; ecc, ectocondyle; enc, entocondyle; j, jugal; m, maxilla; n, nasal; p, parietal; pm, premaxilla; po, postorbital; pt, pterygoid; ptf, pterygoid flange; q, quadrate; qf, quadrate foramen; qj, quadratojugal; retp, retroarticular process of the articular; sa, surangular; sq, squamosal.
DOI: 10.1371/journal.pone.0144695

Christophe Hendrickx , Octávio Mateus and Eric Buffetaut. 2016. Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa.
 PLoS ONE. 11(1): e0144695.  DOI: 10.1371/journal.pone.0144695

[Paleontology • 2014] Semiaquatic Adaptations in a Giant Predatory Dinosaur, Spinosaurus aegyptiacus

Cretaceous Leviathan
The only known dinosaur adapted to life in water, Spinosaurus swam the rivers of North Africa a hundred million years ago. The massive predator lived in a region mostly devoid of large, terrestrial plant-eaters, subsisting mainly on huge fish.

Art: Davide Bonadonna. Sources: Nizar Ibrahim, University of Chicago; Cristiano Dal Sasso and Simone Maganuco, Natural History Museum of Milan | ngm.nationalgeographic.com

ABSTRACT

We describe adaptations for a semiaquatic lifestyle in the dinosaur Spinosaurus aegyptiacus. These adaptations include retraction of the fleshy nostrils to a position near the mid-region of the skull and an elongate neck and trunk that shift the center of body mass anterior to the knee joint. Unlike terrestrial theropods, the pelvic girdle is downsized, the hind limbs are short, and all of the limb bones are solid without an open medullary cavity, for buoyancy control in water. The short, robust femur with hypertrophied flexor attachment and the low, flat-bottomed pedal claws are consistent with aquatic foot-propelled locomotion. Surface striations and bone microstructure suggest that the dorsal “sail” may have been enveloped in skin that functioned primarily for display on land and in water.

Ibrahim, N., Sereno, P., Dal Sasso, C., Maganuco, M., Martill, D., Zouhri, S., Myhrvold, N., Iurino, D. 2014. Semiaquatic Adaptations in a Giant Predatory Dinosaur. Science.
doi: dx.doi.org/10.1126/science.1258750
http://www.sciencemag.org/content/suppl/2014/09/10/science.1258750.DC1/Ibrahim.SM.pdf

Digital skeletal reconstruction and transparent flesh outline of Spinosaurus aegyptiacus. 

Color codes are used to show the origin of different parts of the digital skeletal model.
Bones of the neotype and for Suchomimus tenerensis were CT-scanned, surfaced and size-adjusted before being added to the model.

Color coding: red, neotype (FSAC-KK 11888); orange, Stromer’s bones; yellow, isolated bones from the Kem Kem; green, surrogate bones modeled or taken from the spinosaurids Suchomimus, Baryonyx, Irritator or Ichthyovenator; blue, inferred bones from adjacent bones. A red dot below the posterior dorsal centra shows the approximate position of the center of mass.
Model by Tyler Keillor, Lauren Conroy, and Erin Fitzgerald. | phenomena.nationalgeographic.com

A reconstruction of the skull of Spinosaurus, with known elements in blue.

Art by Davide Bonadonna.

Researchers have long debated whether dinosaurs could swim, but there has been little direct evidence for aquadinos. Some tantalizing hints have appeared, however, in claimed "swim tracks" made by the bellies of dinos in Utah and oxygen isotopes indicating possible aquatic habitats in a group of dinosaurs called spinosaurs. Now, a research team working in Morocco has found the most complete skeleton yet of a giant carnivore called Spinosaurus, very fragmentary remains of which were first discovered in 1912 in Egypt. The new fossils not only confirm that Spinosaurus was bigger than Tyrannosaurus rex, but also show that it had evolutionary adaptations—ranging from pedal-like feet to a nostril far back on the head to high bone density like that of hippos—clearly suited for swimming in lakes and rivers.

Michael Balter. 2014. Giant Dinosaur was a Terror of Cretaceous Waterways. Science. 345(6202): 1232. DOI: dx.doi.org/10.1126/science.345.6202.1232

Scientists Report First Semiaquatic Dinosaur, Spinosaurus

Massive Predator Was More Than 9 Feet Longer Than Largest Tyrannosaurus rex

http://press.nationalgeographic.com/2014/09/11/scientists-report-first-semiaquatic-dinosaur-spinosaurus
http://news.nationalgeographic.com/news/2014/09/140911-spinosaurus-fossil-discovery-dinosaur-science

http://phenomena.nationalgeographic.com/2014/09/11/the-new-spinosaurus

http://www.smithsonianmag.com/science-nature/meet-mighty-spinosaurus-first-swimming-dinosaur-180952679/

http://phys.org/news/2014-09-shark-munching-spinosaurus-first-known-dinosaur.html

http://www.skeletaldrawing.com/home/theres-something-fishy-about-spinosaurus9112014
http://scienceblogs.com/gregladen/2014/09/11/giant-semiaquatic-predatory-dinosaur/
http://paleoillustration.tumblr.com/post/56088019762/spinosaurus-project-digital-and-traditional
facebook.com: Davide Bonadonna

Spinosaurus: The First Semi-Aquatic Dinosaur http://www.science20.com/news_articles/spinosaurus_the_first_semiaquatic_dinosaur-144684 via @science2_0

-------------------------------------------------

pre-2014 PaleoArt 

Spinosaurus aegyptiacus

All Yestered by Rodrigo-Vega on @deviantART