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

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

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

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شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

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

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

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

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

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

   

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

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

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

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