Research interests: Vertebrate taphonomy and paleoecology, fossil record and paleoenvironmental reconstruction. I am particularly interested in dinosaur taphonomy and paleoecology, with special emphasis on the biological and geolgical processes that control their preservation. My current research is focused on the study of Cretaceous dinosaurs from Mexico.
Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Forma... more Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Forma... more Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Abstract Teredolites longissimus, a teredinid boring ichnofossil, is described from log-grounds f... more Abstract Teredolites longissimus, a teredinid boring ichnofossil, is described from log-grounds found in the Cerro del Pueblo Formation of Coahuila, Mexico (Upper Cretaceous). Teredinids, commonly known as shipworms, are marine bivalves that bore into woody substrates and are known from the Jurassic Period to present day. Trace fossils of T. longissimus are taphonomically informative because they provide evidence for the timing and position of wood prior to burial. Colonization and behavior of teredinid bivalves is also dependent on the shipworm density, age of the bivalves, and decomposition of the woody substrate. This study explores the life histories and taphonomic histories of teredinid bivalves and log-grounds in the Cerro del Pueblo and adds to the growing literature on ichnofossils in this deposit.
Abstract This study represents the first description and analysis of insect borings on hadrosaur ... more Abstract This study represents the first description and analysis of insect borings on hadrosaur bones (Dinosauria: Hadrosauridae) from the Late Campanian Cerro del Pueblo Formation (CdP) of the State of Coahuila, Mexico. Here we describe seven different trace patterns that include a new Cubiculum ichnospecies and possible termite damage. The insect bone borings include holes, notches, chambers, furrows, tunnels and rosettes. Transitional structures can also be observed in the hadrosaur bones. Comparisons of these trace morphologies with extant necrophagous insect groups suggest that the CdP borings were likely the result of dermestid beetle larvae and possible termite osteophagy on a dry hadrosaur corpse prior to burial.
Abstract The Cabullona Basin in the state of Sonora, Mexico is becoming recognized due to its div... more Abstract The Cabullona Basin in the state of Sonora, Mexico is becoming recognized due to its diversity of southern Laramidian continental vertebrates, especially dinosaurs. In this study we describe and analyze three theropod teeth (ERNO specimens) that were found isolated and surface collected in the Corral de Enmedio Formation (Cabullona Group, Upper Cretaceous). The three specimens possess similar morphological characteristics that match the ones present in Late Cretaceous Laramidian tyrannosaurids, so they were referred to the Tyrannosauridae, probably belonging to a new unknown taxon. The implementation of statistical and cladistic analyses corroborated their taxonomical assignment. ERNO specimens correspond to the first record of tyrannosaurid dinosaurs in the basal Corral de Enmedio Formation, extending the stratigraphic distribution of these dinosaurs in the Cabullona Basin. Although tyrannosaurids have been previously described in the Cabullona Basin, the ERNO specimens of the Corral de Enmedio Formation seem to be different, because they possess more labiolingually compressed teeth. This new evidence could indicate a higher taxonomic diversity of the tyrannosaurid theropods that were present in the Cabullona Basin, adding more information to the Tyrannosauridae diversification on one of the most southern Laramidian regions during the Late Cretaceous.
The San Juan Raya Formation is world-wide recognized because of its high diversity and abundance ... more The San Juan Raya Formation is world-wide recognized because of its high diversity and abundance of fossil concentrations. In this study nine biofacies, three ichnofacies and ten lithofacies were recognized and interpreted based on the influence of several environmental factors such as water depth change, sedimentation rate, water salinity and substrate consistency. Among these factors it appears that salinity variations were crucial for developing and replacement of the different biofacies. Most of biofacies and ichnofacies inhabited in subtidal, shoreface and inner shelf zones. The aim of this investigation is to provide a comprehensive reconstruction of the different faunal benthonic assemblages and paleoenvironments in a sector of the San Juan Raya Formation during Early Cretaceous time. The results indicate that the paleoenvironmental model for the study area corresponds to a shallow marine, open-coast, storm dominated clastic system, characterized by several variations in sub-...
We report new hadrosaurid juvenile specimens collected from upper Campanian (~72.5 Ma) strata of ... more We report new hadrosaurid juvenile specimens collected from upper Campanian (~72.5 Ma) strata of the Cerro del Pueblo Formation cropping out west of Saltillo (Coahuila, northeastern Mexico). Each of the bones was found isolated and surface collected in three localities; two of them (El Palmar and La Rosa) lie near the town of General Cepeda, whereas the third site (Presa San Antonio) lies 80 km away, near the town of Parras de la Fuente. The remains from La Rosa consist of a fragmentary dentary and maxilla; those from El Palmar include two dentaries, four maxillae, three dental battery fragments, two distal tibiae, and a pedal ungual; and those from Presa San Antonio consist of a nearly complete pubis and a partial femur. All the elements are comparable in size; based on the estimated length of 10 cm for the maxillae and the 25 cm long pubis, femoral length is estimated in 35-45 cm. Their referral to the Hadrosauridae is supported by a horizontally oriented ectopterygoid shelf of th...
En este estudio se llevó a cabo un análisis tafonómico detallado y la posterior reconstrucción de... more En este estudio se llevó a cabo un análisis tafonómico detallado y la posterior reconstrucción del ambiente de depósito de la cantera denominada "El Papalote" ubicada dentro de la Formación Cerro del Pueblo en el estado de Coahuila, México. En dicha cantera, se detectó la presencia de diversos elementos esqueléticos desarticulados de hadrosaurios y tiranosáuridos, los cuales están bien preservados y se depositaron dentro de un ambiente deltaico. Materiales asociados están representados por fragmentos de madera, frutos, huesos de tortugas, gasterópodos y detritos de plantas
ABSTRACT The Lomas Coloradas Formation (Cabullona Group, Upper Cretaceous) in the state of Sonora... more ABSTRACT The Lomas Coloradas Formation (Cabullona Group, Upper Cretaceous) in the state of Sonora, Mexico, has yielded a great diversity of continental vertebrates, especially dinosaurs. In this study we describe, analyze and illustrate six theropod teeth (ERNO specimens) that were found isolated and surface collected. Identification of the specimens is based upon the methodology provided by Smith (2005), Smith et al. (2007) and Smith et al. (2005). The results showed that the ERNO teeth are comparable to those of tyrannosaurid dinosaurs and some of them probably correspond to a new taxon. Their referral to the Tyrannosauridae family is supported by the presence of semi-conical, laterally compressed crowns with an ovoid cross-sectional base; slightly offset carinae with chisel-shaped denticles that are wider labio-lingually than longer proximo-distally; and the presence of enamel wrinkles at the base of some denticles on the labial surface. These wrinkles are not prominent adjacent to the serrations but they take the form of high relief deep enamel bands across the labial and lingual crown faces. Statistical principal component analysis (PCA) and discriminant function analysis (DFA) corroborated the taxonomically assignation of these teeth into this family. Particularly, the DFA analysis yielded very interesting results. This analysis classified ERNO 8549, 8550, 8551 and 8552 specimens as belonging to Tyrannosaurus, so they represent the most southern record of this genus in Western North America. Finally, the misclassification of ERNO 005 and ERNO 006 specimens remains puzzling. It probably was the result of the presence of juvenile individuals.
ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast... more ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast, which was found at a locality in the Cerro del Pueblo Formation, Coahuila, Mexico. The braincase is extremely well preserved and includes almost all bone elements that surrounded the brain. The brain endocast includes all the cerebral regions and cranial nerves. This specimen is similar in shape to the brain described for Gryposaurus notabilis.
Late Cretaceous vertebrates from the Western Interior: New Mexico Museum of Natural History and Science Bulletin, 2006
Abstract—In 2001, a large hadrosaurine preserving extensive cranial and post-cranial material (PA... more Abstract—In 2001, a large hadrosaurine preserving extensive cranial and post-cranial material (PASAC-1) was discovered in an excavation in the Sabinas Basin near the town of Sabinas, Coahuila, Mexico. The specimen can be compared to the anterior portion of a large hadrosaurid skull (IGM 6685) recovered from the central Parras Basin in 1987. Both specimens are from uppermost Campanian strata, and appear to belong to the same taxon as they are both of the same large size and share a similar down-turned dentary. ...
New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of C... more New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Forma... more Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Forma... more Abstract New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Abstract Teredolites longissimus, a teredinid boring ichnofossil, is described from log-grounds f... more Abstract Teredolites longissimus, a teredinid boring ichnofossil, is described from log-grounds found in the Cerro del Pueblo Formation of Coahuila, Mexico (Upper Cretaceous). Teredinids, commonly known as shipworms, are marine bivalves that bore into woody substrates and are known from the Jurassic Period to present day. Trace fossils of T. longissimus are taphonomically informative because they provide evidence for the timing and position of wood prior to burial. Colonization and behavior of teredinid bivalves is also dependent on the shipworm density, age of the bivalves, and decomposition of the woody substrate. This study explores the life histories and taphonomic histories of teredinid bivalves and log-grounds in the Cerro del Pueblo and adds to the growing literature on ichnofossils in this deposit.
Abstract This study represents the first description and analysis of insect borings on hadrosaur ... more Abstract This study represents the first description and analysis of insect borings on hadrosaur bones (Dinosauria: Hadrosauridae) from the Late Campanian Cerro del Pueblo Formation (CdP) of the State of Coahuila, Mexico. Here we describe seven different trace patterns that include a new Cubiculum ichnospecies and possible termite damage. The insect bone borings include holes, notches, chambers, furrows, tunnels and rosettes. Transitional structures can also be observed in the hadrosaur bones. Comparisons of these trace morphologies with extant necrophagous insect groups suggest that the CdP borings were likely the result of dermestid beetle larvae and possible termite osteophagy on a dry hadrosaur corpse prior to burial.
Abstract The Cabullona Basin in the state of Sonora, Mexico is becoming recognized due to its div... more Abstract The Cabullona Basin in the state of Sonora, Mexico is becoming recognized due to its diversity of southern Laramidian continental vertebrates, especially dinosaurs. In this study we describe and analyze three theropod teeth (ERNO specimens) that were found isolated and surface collected in the Corral de Enmedio Formation (Cabullona Group, Upper Cretaceous). The three specimens possess similar morphological characteristics that match the ones present in Late Cretaceous Laramidian tyrannosaurids, so they were referred to the Tyrannosauridae, probably belonging to a new unknown taxon. The implementation of statistical and cladistic analyses corroborated their taxonomical assignment. ERNO specimens correspond to the first record of tyrannosaurid dinosaurs in the basal Corral de Enmedio Formation, extending the stratigraphic distribution of these dinosaurs in the Cabullona Basin. Although tyrannosaurids have been previously described in the Cabullona Basin, the ERNO specimens of the Corral de Enmedio Formation seem to be different, because they possess more labiolingually compressed teeth. This new evidence could indicate a higher taxonomic diversity of the tyrannosaurid theropods that were present in the Cabullona Basin, adding more information to the Tyrannosauridae diversification on one of the most southern Laramidian regions during the Late Cretaceous.
The San Juan Raya Formation is world-wide recognized because of its high diversity and abundance ... more The San Juan Raya Formation is world-wide recognized because of its high diversity and abundance of fossil concentrations. In this study nine biofacies, three ichnofacies and ten lithofacies were recognized and interpreted based on the influence of several environmental factors such as water depth change, sedimentation rate, water salinity and substrate consistency. Among these factors it appears that salinity variations were crucial for developing and replacement of the different biofacies. Most of biofacies and ichnofacies inhabited in subtidal, shoreface and inner shelf zones. The aim of this investigation is to provide a comprehensive reconstruction of the different faunal benthonic assemblages and paleoenvironments in a sector of the San Juan Raya Formation during Early Cretaceous time. The results indicate that the paleoenvironmental model for the study area corresponds to a shallow marine, open-coast, storm dominated clastic system, characterized by several variations in sub-...
We report new hadrosaurid juvenile specimens collected from upper Campanian (~72.5 Ma) strata of ... more We report new hadrosaurid juvenile specimens collected from upper Campanian (~72.5 Ma) strata of the Cerro del Pueblo Formation cropping out west of Saltillo (Coahuila, northeastern Mexico). Each of the bones was found isolated and surface collected in three localities; two of them (El Palmar and La Rosa) lie near the town of General Cepeda, whereas the third site (Presa San Antonio) lies 80 km away, near the town of Parras de la Fuente. The remains from La Rosa consist of a fragmentary dentary and maxilla; those from El Palmar include two dentaries, four maxillae, three dental battery fragments, two distal tibiae, and a pedal ungual; and those from Presa San Antonio consist of a nearly complete pubis and a partial femur. All the elements are comparable in size; based on the estimated length of 10 cm for the maxillae and the 25 cm long pubis, femoral length is estimated in 35-45 cm. Their referral to the Hadrosauridae is supported by a horizontally oriented ectopterygoid shelf of th...
En este estudio se llevó a cabo un análisis tafonómico detallado y la posterior reconstrucción de... more En este estudio se llevó a cabo un análisis tafonómico detallado y la posterior reconstrucción del ambiente de depósito de la cantera denominada "El Papalote" ubicada dentro de la Formación Cerro del Pueblo en el estado de Coahuila, México. En dicha cantera, se detectó la presencia de diversos elementos esqueléticos desarticulados de hadrosaurios y tiranosáuridos, los cuales están bien preservados y se depositaron dentro de un ambiente deltaico. Materiales asociados están representados por fragmentos de madera, frutos, huesos de tortugas, gasterópodos y detritos de plantas
ABSTRACT The Lomas Coloradas Formation (Cabullona Group, Upper Cretaceous) in the state of Sonora... more ABSTRACT The Lomas Coloradas Formation (Cabullona Group, Upper Cretaceous) in the state of Sonora, Mexico, has yielded a great diversity of continental vertebrates, especially dinosaurs. In this study we describe, analyze and illustrate six theropod teeth (ERNO specimens) that were found isolated and surface collected. Identification of the specimens is based upon the methodology provided by Smith (2005), Smith et al. (2007) and Smith et al. (2005). The results showed that the ERNO teeth are comparable to those of tyrannosaurid dinosaurs and some of them probably correspond to a new taxon. Their referral to the Tyrannosauridae family is supported by the presence of semi-conical, laterally compressed crowns with an ovoid cross-sectional base; slightly offset carinae with chisel-shaped denticles that are wider labio-lingually than longer proximo-distally; and the presence of enamel wrinkles at the base of some denticles on the labial surface. These wrinkles are not prominent adjacent to the serrations but they take the form of high relief deep enamel bands across the labial and lingual crown faces. Statistical principal component analysis (PCA) and discriminant function analysis (DFA) corroborated the taxonomically assignation of these teeth into this family. Particularly, the DFA analysis yielded very interesting results. This analysis classified ERNO 8549, 8550, 8551 and 8552 specimens as belonging to Tyrannosaurus, so they represent the most southern record of this genus in Western North America. Finally, the misclassification of ERNO 005 and ERNO 006 specimens remains puzzling. It probably was the result of the presence of juvenile individuals.
ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast... more ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast, which was found at a locality in the Cerro del Pueblo Formation, Coahuila, Mexico. The braincase is extremely well preserved and includes almost all bone elements that surrounded the brain. The brain endocast includes all the cerebral regions and cranial nerves. This specimen is similar in shape to the brain described for Gryposaurus notabilis.
Late Cretaceous vertebrates from the Western Interior: New Mexico Museum of Natural History and Science Bulletin, 2006
Abstract—In 2001, a large hadrosaurine preserving extensive cranial and post-cranial material (PA... more Abstract—In 2001, a large hadrosaurine preserving extensive cranial and post-cranial material (PASAC-1) was discovered in an excavation in the Sabinas Basin near the town of Sabinas, Coahuila, Mexico. The specimen can be compared to the anterior portion of a large hadrosaurid skull (IGM 6685) recovered from the central Parras Basin in 1987. Both specimens are from uppermost Campanian strata, and appear to belong to the same taxon as they are both of the same large size and share a similar down-turned dentary. ...
New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of C... more New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
Desde la primera publicación científica en el año de 1880, los dinosaurios se han considerado com... more Desde la primera publicación científica en el año de 1880, los dinosaurios se han considerado como uno de los fenómenos más importantes dentro de la Paleontología de vertebrados, ya que éstos correspondieron a uno de los mayores éxitos evolutivos que ocurrieron en nuestro planeta, siendo los organismos dominantes de los ecosistemas terrestres por alrededor de 160 millones de años. Debido a que los dinosaurios poseen un gran atractivo y una enorme accesibilidad que trasciende fronteras, éstos ofrecen convertirse en un modelo ideal de introducción a la ciencia para estudiantes de diferentes niveles escolares. De esta manera, el estudio de este grupo de organismos nos permite adentrarnos en el pasado remoto y así conocer el funcionamiento de la naturaleza dentro de los ecosistemas de la era Mesozoica. En la actualidad, se han descubierto fósiles de dinosaurios en todos los continentes; sin embargo, los yacimientos más productivos a nivel mundial se encuentran ubicados a todo lo largo de la Cordillera del Oeste de Norteamérica, desde Alaska hasta el Norte de México, lo que representa el mayor transecto conocido de distribución latitudinal para este tipo de organismos. Particularmente en el caso de México, se han encontrado numerosas localidades que contienen restos de dinosaurios en diferentes estados, como son: Baja California, Sonora, Chihuahua, Coahuila, Tamaulipas, Michoacán, Puebla y Oaxaca. Estos descubrimientos tienen gran relevancia dentro del ámbito mundial, ya que la mayoría corresponden a nuevos géneros y especies, indicando que nuestro país albergó una elevada paleodiversidad de dinosaurios endémicos, lo cual le ha valido ser considerado como un verdadero paraíso para los paleontólogos. En la actualidad, el estudio de los dinosaurios mexicanos resulta bastante prometedor, ya que no sólo se están haciendo investigaciones taxonómicas para determinar qué tipos de dinosaurios habitaron en nuestro país; sino que además, se están aplicando nuevas metodologías multidisciplinarias que permitirán la reconstrucción de los ecosistemas mesozoicos terrestres y así mostrar a las nuevas generaciones la enorme riqueza de nuestro patrimonio paleontológico.
I offer you to publish a scientific paper about paleontology (any kind of specialization) if you ... more I offer you to publish a scientific paper about paleontology (any kind of specialization) if you accept the coauthority. Thanks
I offer you to publish a scientific paper about paleontology (any kind of specialization) if you ... more I offer you to publish a scientific paper about paleontology (any kind of specialization) if you accept the coauthority. Thanks
I offer you to publish a scientific paper about paleontology (any kind of specialization) if you ... more I offer you to publish a scientific paper about paleontology (any kind of specialization) if you accept the coauthority. Thanks
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