16.10.17 0 comentarios

El registro fósil de allosauroides del Jurásico Superior de la cuenca lusitánica en la XXII Bienal de la RSEHN


Durante la XXII Bienal de la RSEHN celebrada en Coimbra (Portugal) se presentó un análisis de la diversidad de allosauroides conocida a partir del registro fósil del Jurásico Superior portugués. Este registro incluye diversos ejemplares que representan una gran diversidad, aunque con una posición filogenética problemática, lo que dificulta la interpretación paleobiogeográfica de este grupo de terópodos. Con todo, la interpretación de algunos taxones de terópodos como formas exclusivas del registro portugués y la reinterpretación de diversos ejemplares (previamente considerados como pertenecientes a especies compartidas con el registro de la Formación Morrison) como formas exclusivas de la cuenca lusitánica, sugiere procesos de vicarianza incipiente en la evolución de las faunas de terópodos del Jurásico Superior en ambos lados del proto-Atlántico Norte. El resumen es el siguiente:

Allosauroidea is a clade of large-bodied theropod dinosaurs that ranged from the Middle Jurassic to the Late Cretaceous (Brusatte & Sereno, 2008). This clade includes the Late Jurassic theropod Allosaurus, which is a well-known dinosaur genus, represented by hundreds of specimens from the North American Morrison Formation. Allosauroids represent an important group for the study of the Mesozoic palaeobiogeography because they comprise a long-lived and diverse group that evolved during the fragmentation of Pangaea (e.g. Pérez-Moreno et al., 1999; Sereno, 1999a,b; Upchurch et al., 2002).
The fossil record of allosauroid theropods from the Upper Jurassic of the Lusitanian Basin is abundant and diverse. Currently, this record includes Lourinhanosaurus (Mateus, 1998), Allosaurus (Pérez-Moreno et al., 1999; Mateus et al., 2006), and some specimens with an uncertain phylogenetic position that share some features, but also differences with Lourinhanosaurus and Allosaurus (Malafaia et al., 2016). Lourinhanosaurus antunesi is represented by a set of postcranial elements collected in Peralta (Lourinhã). It was originally described as an allosauroid (Mateus, 1998) and latter interpreted as a more basal tetanuran closely related with megalosaurids (Mateus et al., 2006). Subsequently, it was recovered as a member of the basal allosauroid clade Metriacanthosauridae by Benson (2010) and as a possible coelurosaur by Carrano et al. (2012). A recent phylogenetic analysis including some theropod specimens from the Upper Jurassic of Portugal supports the interpretation of Lourinhanosaurus as a member of Allosauroidea, but placed this taxon at the base of a more derived group comprising Allosaurus + Carcharodontosauria (Malafaia et al., 2016).
Allosaurus is the most abundant and well represented allosauroid taxon currently known in the Lusitanian Basin. This taxon is represented by a set of cranial and postcranial remains found in Praia de Vale Frades (Lourinhã), Andrés (Pombal), and Guimarota (Leiria) (Pérez-Moreno et al., 1999; Rauhut & Fechner, 2005; Mateus et al., 2006; Malafaia et al., 2010). A specimen collected in Andrés was assigned to the species Allosaurus fragilis described in the Morrison Formation. This specimen is the first evidence of Allosaurus outside North America and was considered in that moment the first dinosaur species present in two continents. This discovery triggered an intense discussion concerning the paleobiogeographic relationships of Late Jurassic dinosaur faunas from the Lusitanian Basin and the Morrison Fm. The presence of A. fragilis in both continents was interpreted as an evidence of faunal interchanges across the North Atlantic Ocean during the Late Jurassic. Later, a partial skull collected in Praia de Vale Frades was interpreted as belonging to a new Allosaurus species: Allosaurus europaeus (Mateus et al., 2006). In 2005, several osteological remains assignable to Allosaurus were found in the Andrés fossil site, including abundant cranial elements. These specimens show some differences when compared with A. fragilis, but also with the holotype of A. europaeus. The currently known Upper Jurassic record of allosauroid theropods from Portugal includes a relatively large number of specimens with a great diversity, but with an uncertain phylogenetic position, which difficult the study of the paleobiogeography of this group.
The identification of some theropod taxa interpreted as exclusive from the Portuguese record and the reinterpretation of several specimens previously considered as species shared with the Morrison Fm. as forms exclusive of the Lusitanian Basin suggest an incipient vicariant evolution of the Late Jurassic theropod faunas from both margins of the proto-North Atlantic Ocean.

Referencia:
  • Malafaia, E., P. Mocho, F. Escaso, F. Ortega. 2017. The fossil record of Allosauroidea (Dinosauria, Theropoda) from the Upper Jurassic of the Lusitanian Basin: diversity and paleobiogeographic interpretation. XXII Bienal de La Real Sociedad Española de Historia Natural. Libro de Resúmenes 246–247.
11.10.17 0 comentarios

La tortuga de Porto de Mos en la XXII Bienal de la RSEHN


Como ha sido indicado en este blog, el ejemplar de Plesiochelyidae procedente del Oxfordiense de Porto de Mos (Portugal) ha sido presentado en la XXII Bienal de la RSEHN en Coimbra (Portugal). Este espécimen fue reconocido como uno de los pocos de un Plesiochelyidae hallados en niveles pre-kimmeridgienses y como el más antiguo representante de este grupo identificado a nivel genérico (ver aquí). El resumen es el siguiente:

The most abundant and diverse group of turtles in the Iberian record is Eucryptodira. It is represented by its crown group, Cryptodira, but also by several Mesozoic forms belonging to its stem group. The oldest lineage corresponds to Plesiochelyidae, a clade exclusive of the European Upper Jurassic record. These marine turtles were not adapted to a pelagic life, being inhabitants of coastal environments, mostly related to mid and inner shelf, open or rimmed carbonated systems. The plesiochelyids disappeared during the Jurassic–Cretaceous transition as result of the regression of the shallow shelf seas of Europe, probably due to a drastic reduction of their habitat.
Several plesiochelyid representatives have been recognized in the Kimmeridgian and Tithonian Iberian records, all of them being identified in the Portuguese Lusitanian Basin (see Pérez-García accepted and references therein). The first described member of Plesiochelyidae in the Iberian record was ‘Plesiochelys choffati’, from the Tithonian of Vila Franca do Rosario (Mafra, Portugal). It is now identified as belonging to Craspedochelys, a genus relatively common in the Kimmeridgian and Tithonian levels of the Lusitanian Basin. The presence of the genus Plesiochelys was subsequently confirmed in the Tithonian record of both Portugal and Spain. The presence of a third genus of Plesiochelyidae (i.e. Tropidemys) has recently been recognized in both the upper Kimmeridgian–lower Tithonian levels of Portugal and in the Tithonian record of Spain. This taxon is probably represented by two species.
The pre-Kimmeridgian record of Plesiochelyidae is poorly known. In fact, the only currently known specimens come from the Iberian record. The first one was found in upper Oxfordian beds from Sierra de Cazorla (Jaén, Spain). It corresponds to a relatively complete shell recognized to the holotype of a putative new taxon, ‘Hispaniachelys prebetica’. However, this taxon is now considered as nomen dubium, and the specimen is presently identified as belonging an indeterminate representative of Plesiochelyidae.
The second one is a shell from an upper Oxfordian section of the Lusitanian Basin (see Pérez-García et al., accepted). It comes from Alqueidão da Serra (Municipality of Porto de Mós). Several artisanal quarries have been working for a long time in this area, yielding a variety of Jurassic light grey limestones and the famous “black limestone”, a dark mudstone with quite dark, uniform color, mainly used to produce ubiquitous Portuguese cobblestone designs (“calçada portuguesa”), a traditional art internationally recognized. These carbonate layers also are quite fossiliferous and rich of invertebrate specimens, whichmostly belong to fresh to brackish, marginal marine environments. The turtle shell was found by Adolfo Correia de Carvalho (1934-2010), owner and worker of a local quarry, during the first months of 1989. It was carefully collected from its limestone cast and offered as a donation to the Museu Municipal de Porto de Mós, yet in process of constitution at that time.
Registered and incorporated as MMPM37 by Francisco Furriel (1925-2014), a local collector and first director of the museum, the turtle shell stood out side to side with many other fossil specimens and rocks, mostly collected from Middle and Upper Jurassic, and Upper Cretaceous outcrops of the nearby region. Despite to be separated in two pieces and exhibited without any previous preparation, this fossil merited through years the curiosity of the visitors.
Due to its rarity, the turtle shell from Porto de Mós also deserved a prominent place in the museum catalogue. However, until very recently, it has not been subjected to any detailed taxonomic study. Nowadays, a plan of the Council board to move the museum to another building with a new exhibition, was recently taken as an excellent opportunity to study this specimen, as a contribution to better understand this group of Jurassic vertebrates.
The specimen MMPM37 represents the oldest remain of a turtle identified in the Portuguese record, constituting the second identification of a plesiochelyid performed in pre-Kimmeridgian levels in all of Europe. This specimen can also be recognized as the only Oxfordian plesiochelyid identified at generic level.
_____
Referencia: 
  • Pérez-García, A., J. M. Brandão, P. M. Callapez, L. Machado, E. Malafaia, F. Ortega, and V. F. dos Santos. 2017. A plesiochelyid turtle from the upper Oxfordian of Porto de Mós (West Central Portugal). XXII Bienal de La Real Sociedad Española de Historia Natural. Libro de Resúmenes 268–269.
10.10.17 0 comentarios

Una nueva visión sobre la enigmática tortuga primitiva Kallokibotion


Una de las tortugas más singulares del registro europeo es Kallokibotion. Esta tortuga, definida en Rumanía, corresponde a una especie que vivió muchos millones de años después de lo que cabría esperar. De hecho, se trata de una tortuga primitiva (es decir, de un linaje más basal que la divergencia Jurásica de Cryptodira como Pleurodira), que habitó al final de la “era de los dinosaurios”, durante el final del Cretácico Superior.


Kallokibotion fue descrita hace casi un siglo por el célebre paleontólogo Franz Nopcsa, quizá uno de los investigadores más pintorescos de cuantos han trabajado en esta disciplina científica, y cuya vida ha sido retratada tanto en libros como en el mundo cinematográfico. Esta tortuga fue un animal especial para Nopcsa ya que, a pesar de su descripción de numerosas especies fósiles, Kallokibotion bajazidi fue la escogida para homenajear a su amante Bajazid Doda, el nombre de esta tortuga significando “la caja hermosa de Bajazid”.

Aunque Nopcsa identificó varios ejemplares atribuibles a esta extraña tortuga, su preservación era mala. Por lo tanto, a pesar de ser muy relevante, la información detallada sobre esta forma era, hasta ahora, muy limitada. Muchos trabajos realizados en las últimas décadas y, especialmente, en tiempo reciente, han considerado esta tortuga. Sin embargo, la ausencia de hallazgos y estudios de nuevos ejemplares dificultó el avance en el conocimiento sobre la misma, así como sobre la evolución de estas tortugas primitivas. Así, su posición filogenética precisa estaba en discusión, formando parte de todas las filogenias generales de tortugas, así como de aquellas sobre formas primitivas.


Un nuevo trabajo, que acaba de ser publicado, presenta por fin nuevo y abundante material, muy bien preservado, atribuible a esta tortuga. Se reconocen caparazones, pero también elementos apendiculares, axiales y restos craneales, incluyendo un cráneo y gran parte del esqueleto de un ejemplar adulto. Los nuevos ejemplares aportan numerosa información nueva sobre la anatomía tanto craneal como del resto del esqueleto de esta tortuga. Además, permiten refutar numerosas interpretaciones anatómicas previas, que resultaban erróneas por haber sido deducidas a partir de ejemplares deformados y mal preservados. Este estudio permite caracterizar a Kallokibotion como una de las tortugas primitivas mejor conocidas a nivel mundial, estableciéndose su parentesco con las otras formas conocidas.
_____
Más información:
4.10.17 0 comentarios

Una de terópodos (o no) en la XXII Bienal de la RSEHN


La semana pasada se presentó en la XXII Bienal de la Real Sociedad de Historia Natural celebrada en la ciudad portuguesa de Coimbra la reevaluación de unos restos axiales articulados dentro de un bloque de arenisca que han formado parte hasta hace poco de la exposición permanente de dinosaurios del Museu Nacional de História Natural e da Ciência (MUHNAC) en Lisboa.

Los resultados preliminares presentados en este congreso indican que los restos presentes en este bloque de arenisca no pertenecen, como hasta ahora se había creído, al dinosaurio terópodo ‘Megalosaurus insignis’. Por el contrario, esta serie vertebral en articulación muestra una combinación de caracteres que relacionan a esta ejemplar con los dinosaurios ornitópodos cercanamente emparentados con formas como Camptosaurus.

Aquí está el resumen:

Megalosaurus Buckland (1824) was the first non-avian dinosaur genus described and one of the three genera which Owen defined Dinosauria in 1842. Nevertheless, since its discovery, Megalosaurus is considered a waste-basket taxon for which more than thirty species have been described. Some of these controversial species were described in the Portuguese fossil record during the mid-twentieth century by Lapparent & Zbyszewski (1957) including Megalosaurus insignis, Megalosaurus pannoniensis, Megalosaurus pombali and Megalosaurus superbus.
One of the Portuguese specimen assigned to M. insignis consists of a sandstone block in which five articulated vertebrae are included, three of them having the proximal part of the left ribs in articulation. This specimen comes from the area of Praia de Areia Branca in Lourinhã municipality. Lapparent & Zbyszewski (1957) described and figured the specimen and identified it as a partial articulated set of five anterior caudal vertebrae of a the theropod dinosaur M. insignis. However, an ongoing re-evaluation of the specimen, housed at the Museu Nacional de História Natural e da Ciência in Lisbon, does not support the interpretation of Lapparent & Zbyszewski (1957).
The preserved dorsal series is characterized by low, cylindrical centra, clearly visible neurocentral sutures and parapophyses positioned at the base of the transverse processes. All of these features suggest that this specimen is related to ornithopod dinosaurs because the combination of them is unknown in theropod dinosaurs. In addition, the overall morphology of the vertebrae resembles that of camptosaur-grade ankylopollexians but pending further preparation of the specimen, it is tentatively referred to an indeterminate ankylopollexian.”

-----
Referencia:
  • Escaso, F., Malafaia, E., Mocho, P., Narváez, I., Ortega, F. 2017. ‘Megalosaurus insignis’ from Praia de Areia Branca (Lourinhã, Portugal): is it Theropoda or Ornithopoda?. Livro de Resumos da XXII Bienal da RSEHN - Coimbra, 227.
2.10.17 0 comentarios

Estuvimos en la XXII Bienal de la RSEHN en Coimbra (Portugal)


La Real Sociedad Española de Historia Natural ha celebrado su XXII reunión Bienal durante los días 6 al 9 de Septoiembre en distintas dependencias de la Universidad de Coimbra (Portugal). El tema central de la Bienal ha sido "Los mapas de la Nauraleza", por lo que la cartografía ha sido la protagonista del encuentro. Además, tambien ha habido comunicaciones y posters dedicados a la paleontologogía de vertebrados, en algunos de los cuales han participado colaboradores de este blog.
Estos han sido:
    Se pueden consultar los detalles de la reunión y los resúmenes publicados en las siguientes URLs:
      27.9.17 0 comentarios

      Un posible nuevo carcharodontosáurido del Cretácico Inferior de Patagonia en el 77th Annual Meeting de la SVP


      Entre los trabajos presentados en el pasado 77th Annual Meeting de la SVP, se encontraba este resumen de Rodolfo Coria y colaboradores sobre unos restos de dinosaurio terópodo procedentes de la Formación Mulichinco (Neuquén, Argentina), que podrían representar el carcharodontosaurido más antiguo del registro fósil sudamericano. El resumen es el siguiente:

      Skeletal remains corresponding to an adult specimen of an allosauroid theropod (MLLPv-007) were collected in the sandstones of the Mulichinco Formation (Valanginian, Lower Cretaceous of the Neuquén Basin). The specimen includes the tip of the snout, some postdentary bones, vertebrae (cervicals, dorsals, sacrals and caudals), ribs, and fragments of the pelvic girdle. The cervico-dorsal section consists of five complete, articulated vertebrae (the three last cervicals and first two dorsals) with cervical ribs attached. Nine posterior dorsal vertebrae are represented by portions of the neural arches and centra, and are still attached to their ribs. The three preserved sacral vertebra are very pneumatic, and the four articulated caudals are from the middle to distal part of the tail.
      The hip elements are fragmentary but include the dorsal margin of the supracetabular blade, the pubic peduncle, and fragments of the pubis. The sculptured lateral surface of the maxilla, the moderately sized cervical epipophyses, the presence of sacral pleurocoels, and the well-developed prespinal laminae in the caudals form a combination of characters present in allosauroid theropods. A preliminary cladistical analysis links this specimen with carcharodontosaurid theropods by having a single unambiguous synapomorphy — a maxilla with a sculptured external surface. These are the first reported theropod remains from the formation, which is associated stratigraphically with dicraeosaurid sauropods and non-hadrosaurid ornithopods. The Bajada Colorada Fm partially overlaps the Mulichinco Formation temporally, and has yielded fragmentary and poorly preserved theropod remains assigned to abelisauroid and megalosaurid theropods.
      Thus, the Mulichinco specimen would represent the oldest carcharodontosaurid record from South America, and suggests that the evolutionary history of this clade in the continent is older than thought.
      Grant Information: Research supported by grants from PIP-CONICET 0233/0683, University of Río Negro and Municipalidad de Las Lajas (Neuquén) (to R.A.C).
      ---
      Más información:
      • Referencia:  Coria, R. A.; Currie, P. J.; Ortega, F.; Baiano, M. (2017) A possible carcharodontosaurid theropod record from the Valanginian (Early Cretaceous) of Patagonia, Argentina. 77th Annual Meeting of SVP. Abstract book. Calgary, Canada. 100.
      20.9.17 0 comentarios

      La anatomía craneal de Allosaurus en el yacimiento de Andrés (Jurásico Superior, Portugal) en el 77th Annual Meeting de la SVP


      En el 77th Annual Meeting de la Society of Vertebrate Paleontology que este año se ha celebrado en Calgary, Alberta, se presentó una discusión de la anatomía craneal de un ejemplar de Allosaurus descubierto en el yacimiento de Andrés (Jurásico Superior, Portugal). Este ejemplar incluye un cráneo parcial, desarticulado que representa el conjunto craneal más completo de un dinosaurio terópodo conocido actualmente en el registro portugués. Los elementos están además muy bien preservados permitiendo la descripción de diversas estructuras que están mal conocidas en el registro fósil de terópodos y el conocimiento detallado de la morfología craneal de este ejemplar. 

      El ejemplar de Andrés es muy difícilmente distinguible de las formas norte americanas de Allosaurus fragilis pero presenta algunas diferencias relativamente a esta especie. Por otro lado, presenta también diferencias relativamente a la especie portuguesa Allosaurus europaeus en particular en una de las autapomorfias propuestas en la diagnosis de esta especie. Sin embargo, con base en el contexto paleobiogeográfico optamos por asignar, por el momento, el ejemplar de Andrés a Allosaurus cf. europaeus aguardando un mejor conocimiento de las relaciones de parentesco entre los miembros de Allosaurus de Portugal y da América do Norte. El resumen es el siguiente:

      The description, in 1999, of a partial skeleton of a theropod dinosaur collected in the Andrés fossil site from the Upper Jurassic of the Lusitanian Basin and assigned to the North American species Allosaurus fragilis promoted an interesting paleobiogeographic discussion about the relationship of the Late Jurassic dinosaur faunas from Portugal and North America. The similarity of these faunas was explained by the existence of faunal exchanges across the proto-North Atlantic Ocean at the end of the Jurassic due the presence of intermittent land bridges between the landmasses of North America and Iberia. Later, the description of the new species Allosaurus europaeus as well as other vertebrate taxa exclusive from the Lusitanian Basin supports a different scenario in which the evolution of these faunas would be marked by vicariant processes. A set of cranial and postcranial remains collected in the Andrés fossil site in 2005 and 2010 allows a better knowledge of the cranial morphology and diversity of the Portuguese forms of Allosaurus and may add important data for the paleobiogeographic discussion. These specimens include approximately 85% of a complete skull representing the most complete set of theropod cranial remains known from the Upper Jurassic of Portugal. These elements are fairly well preserved allowing the description of several fragile elements and structures that are poorly known in the fossil record of theropods, allowing achieve a detailed knowledge of the cranial morphology of this theropod. These specimens show some differences relative to the Allosaurus specimens from the Morrison Formation, but have also some variations relative to the Portuguese species A. europaeus. However, based on the paleobiogeographic context of the specimens from Andrés it is more reliable to assign these specimens to Allosaurus cf. europaeus pending to establish a robust interpretation of the relationships between the Portuguese and North American members of Allosaurus.

      -----
      Más información:
      • Referencia: Malafaia, E.; Mocho, P.; Escaso, F.; Dantas, P.; Ortega, F. 2017. Analysis of the cranial anatomy of Allosaurus from the Andrés fossil site (Portugal, Upper Jurassic). 77th Annual Meeting of SVP, abstract book, 157.
      19.9.17 0 comentarios

      El área de nidificación de Poyos en el 77th Annual Meeting de la SVP


      El primer resto fósil de un dinosaurio en Guadalajara fue descrito en 2009. Se trataba de una vértebra caudal aislada, de un saurópodo titanosaurio, hallada en el Cretácico Superior Sacedón, en las cercanías del antiguo pueblo de Poyos o Santa María de los Poyos (Guadalajara) (ver información aquí). Un nuevo proyecto, actualmente en curso, ha permitido reconocer esta región fosilífera como de gran interés. Así, el yacimiento paleontológico ubicado en el término municipal de Sacedón, conocido como el yacimiento de Poyos, no sólo está aportando restos óseos muy relevantes, de tortugas, cocodrilos y, especialmente dinosaurios saurópodos y terópodos, sino que supone un área de nidificación singular.

      Al mismo tiempo que se trabajaba en la excavación, algunos de los primeros resultados científicos fueron presentados en el 77 congreso de la Society of Vertebrate Paleontology, celebrado en Canadá.

      Su resumen es el siguiente:

      Several outcrops providing fossil remains of dinosaurs and other reptiles from the uppermost Cretaceous (Campanian and Maastrichtian) are known in the Villalba de la Sierra Formation (Central Spain), in the provinces of Cuenca and Guadalajara (Castilla-La Mancha). Numerous osseous remains of several clades of reptiles, the most abundant being the turtles (especially Bothremydidae), crocodiles (Allodaposuchidae) and dinosaurs (especially Titanosauria), were found in Lo Hueco fossil site (Cuenca). Remains of eggs were not identified there. However, they were recognized in the nearby site of Portilla (Cuenca) by abundant isolated fragments attributed to Megaloolithus siruguei. However, osseous remains are not present in this site.
      Only an isolated dinosaur remain was so far known in the Villalba de la Sierra Formation levels of the adjacent province of Guadajalara: a caudal vertebra of a titanosaurian found in the area of Buendía (Sacedón). Recent paleontological surveys have been carried out for the first time in this area. As a result, several fossiliferous levels have been identified. Several remains of a medium-size theropod, probably corresponding to an abelisaurid ceratosaurian, are included among the new osseous elements. This finding is relevant considering the very scarce available record of this clade in the Iberian Upper Cretaceous record. Buendía is the first region of the Villalba de la Sierra Formation where both osseous and eggs remains are found. Thus, a level with abundant small fragments of eggs has also been recognized. However, the most relevant of the findings performed there is another level with abundant complete eggs. Although they correspond to dinosaur eggs probably belonging to Megaloolithidae, they cannot be attributed to Megaloolithus siruguei.
      Therefore, the fossiliferous area of Buendía is recognized as singular considering several aspects. The only so far known outcrops of the Villalba de la Sierra Formation with remains of vertebrates in the province of Guadalajara are located there. Contrasting with the fossil sites previously identified in this Formation (Lo Hueco and Portilla), both bones and eggs are recognized in Buendía. Remains of medium-size theropods, poorly represented in this Formation, have been found. The ootaxon hitherto known in this Formation, Megaloolithus siruguei, is not the one found in Buendía. The first complete eggs of Central Spain, and also the first dinosaur nesting area of this region, are recognized for the first time.
      -----
      Más información:
      • Referencia: Pérez-García, A.; Gascó, F.; Ortega, F. 2017. A singular uppermost Cretaceous dinosaur nesting area in the Villalba de la Sierra Formation (Guadalajara, Central Spain). 77th Annual Meeting of SVP. Abstract book: 176.
      18.9.17 0 comentarios

      Las colas de los titanosaurios de Lo Hueco en el 77th Annual Meeting de la SVP


      Desde su descubrimiento en 2007, hace diez años, el yacimiento de Lo Hueco ha aportado una ingente cantidad de material sobre los vertebrados fósiles de finales del Cretácico. Los saurópodos titanosaurios son especialmente abundantes y diversos en el yacimiento, y el estudio de su variabilidad cada vez arroja más luz sobre su aspecto y relaciones de parentesco.

      Un estudio preliminar sobre la diversidad funcional de las colas de estos dinosaurios ha sido presentado en el 77 congreso de la Society of Vertebrate Paleontology. Aquí tenéis el resumen del trabajo presentado:

      Lo Hueco is an Upper Cretaceous (Campanian-Maastrichtian) macro-vertebrate fossil site, where more than fourteen partially articulated and/or associated titanosaur sauropod specimens have been found. So far, only Lohuecotitan pandafilandi and a braincase tentatively referred to cf. Ampelosaurus sp., have been identified. The presence of several articulated titanosaur caudal series and the usage of 3D modelling is a unique opportunity for morphofunctional and biomechanical analyses.
      The preliminary description of six proximal-middle caudal series (with totally fused neurocentral sutures) suggests the presence of four different morphotypes. Morphotype I has short, anteriorly curved neural spines, high pedicels, and dorsally inclined prezygapophyses. Morphotype II has longer and posteriorly inclined neural spines; short pedicels; slender, long and horizontal prezygapophyses and postero-distally curved anterior chevrons. Morphotype III has short, anteroposteriorly expanded distal end of the neural spines, high pedicels, horizontal and short prezygapophyses and straight chevrons.
      Finally, the tail of Lohuecotitan does not belong to the abovementioned morphotypes, as it has straight and perpendicular anterior neural spines, anteroposteriorly short pedicels, horizontal prezygapophyses and straight chevrons.
      Considering the neural spines orientation, which corresponds to the resultant force of the individual forces exerted by muscles and ligaments, Morphotype I would have had a stronger posterior force acting upon the spine, Morphotype II would have had a stronger anterior force acting upon the spine and Morphotypes III and Lohuecotitan would have had the anterior and posterior forces at balance. The further the pre-postzygapophyseal contact gets from the articulation of centra, the smaller the range of motion is, so Morphotypes I and III would have had more restricted ventriflexion than morphotypes II and Lohuecotitan. The distally curved chevrons of Morphotype II imply a smaller relative attachment area for the caudofemoral musculature compared with the straight chevrons of Morphotype III and Lohuecotitan.
      This preliminar analysis suggests the titanosaurs from Lo Hueco had very different forces acting upon their caudal vertebrae, ranges of motion and muscular surface insertions. Future analyses will help to evaluate the relation among different type of motions and body plans, as well as their taxonomical significance.

      -----
      Más información:
      • Vidal, D., Sanz, J., Mocho, P., Páramo, A., Escaso, F., Marcos, F., Ortega, F. 2017. The titanosaur tails from Lo Hueco (Cuenca, Spain): Four different ways to shake?. 77th Annual Meeting of SVP. Abstract book. 208.
      14.9.17 0 comentarios

      El cráneo de Concavenator en el 77th Annual Meeting de la SVP


      Concavenator ha sido despiezado y repartido por el mundo, los brazos se contaron en Salas de los Infantes, el esqueleto axial viajó hasta Munich en la EAVP y, ahora, la pieza que faltaba: el cráneo, ha viajado hasta Calgary para la SVP. Si, si, viajado literal y es que, como veis en la foto, con Elena y Daniel fue una reconstrucción en formato de bolsillo impresa en 3D (Muchas gracias a los autores de esta impresión).

      El trabajo presentado describía las características observadas en el cráneo de Concavenator, definiéndose una serie de sinapomorfías de Carcharodontosauridos y autapomorfías del ejemplar. Además, se realizaba una reconstrucción en 3D a partir de un escaneo por fotogrametría del cráneo. Las partes que no se han preservado en el ejemplar de Concavenator fueron reconstruidas en base a las comparaciones con taxones relacionados como Allosaurus y Acrocanthosaurus. Todo el modelado en 3D fue llevado a cabo con el programa Zbrush.

      Para más detalle del trabajo, ahí va el resumen del póster:

      Concavenator corcovatus is a carcharodontosaurid dinosaur known from only an almost complete and articulated skeleton, MCCM-LH 6666, from 'Las Hoyas' fossil site (Early Cretaceous, Spain). The fossil is embedded in fine laminated limestone, with only the right elements of the skull visible in lateral view. The skull of Concavenator is almost complete, except for the anteriormost and posteriormost regions, which are broken. Therefore, several posterior skull bones are missing.
      Here, a review of the cranial anatomy of Concavenator has been carried out in order to further test its phylogenetic relationships. This included a detailed osteological description of the skull and comparing its features with those of other allosauroids. This description has provided a wide revision of the cranial anatomy of carcharodontosaurids, relevant to their general phylogenetic relationships.
      This review shows the skull of Concavenator shares several allosauroid and carcharodontosaurid synapomorphies. Concavenator has, as other allosauroids, i) a low and longitudinal lateral ridged on the dorsolateral rim of the nasal, ii) a low, broad and rugose lacrimal horn, iii) several foramina on lateral surface of the lacrimal, iv) pneumatic recess on the palatine, and v) two posterior foramina on the surangular. Concavenator shares numerous apomorphies with other carcharodontosaurids: i) a lacrimal-postorbital contact, ii) a well-developed postorbital boss, iii) anteroventrally oriented postorbital ventral process, iv) an intraorbital process in the postorbital, v) rostrally projected roughness in the dorsal surface of the postorbital, vi) a notch in the ascending ramus of the maxilla, vii) a sulcus on the anterior margin of the lacrimal ventral ramus, viii) curved dorsal surface of lacrimal, and ix) frontal-parietal fused contact. Finally, Concavenator has two cranial autapomorphies: i) connection between the recess on the lateral surface of the nasal and ii) a rounded morphology of the ventral surface of the postorbital boss. In addition, anatomical comparison mostly with Allosaurus and Acrocanthosaurus, as well as other carcharodontosaurids, has enabled to reconstruct the missing regions of the skull. Here, we propose the first complete 3D reconstruction of the skull of Concavenator, based on the integration of the anatomical data of the clade. The skull model was generated from a superficial photogrammetric scan with the missing information sculpted with CAD software.
      -----
      Más información:
      • Cuesta, E.; Vidal, D.; Ortega, F.; Sanz, J. L. The Skull of Concavenator corcovatus (Dinosauria: Theropoda) from Las Hoyas (Early Cretaceous, Spain): Osteology and 3D Reconstruction. 77th Annual Meeting of SVP, abstract book, 101.