Publicación: Análisis de la evolución neurocraneal en la radiación temprana de Eusuchia
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2019-06-06
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Atribución-NoComercial-SinDerivadas 4.0 Internacional
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Universidad Nacional de Educación a Distancia (España). Escuela Internacional de Doctorado. Programa de Doctorado en Ciencias
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Los crocodilomorfos son un linaje de gran éxito evolutivo, abarcando 230 millones de años desde su origen, a finales del Triásico, hasta la actualidad. Los restos de estos animales son comunes en yacimientos mesozoicos y cenozoicos de todo el globo, mostrando una gran diversidad y abundancia en estos ecosistemas pretéritos. Entre estos, destaca el yacimiento de Lo Hueco (Cretácico Superior, Fuentes, Cuenca), por la elevada cantidad y excepcional preservación de restos de crocodilomorfos hallados. Los caracteres morfológicos observados en los especímenes extraídos en el yacimiento de Lo Hueco han permitido establecer tres morfotipos de eusuquios basales, dos de ellos atribuidos a nuevas especies endémicas de este yacimiento: Lohuecosuchus megadontos, Agaresuchus fontisensis y Allodaposuchidae indeterminado. En la presente tesis doctoral se reconstruyen y describen las cavidades intracraneanas de varios de los ejemplares de eusuquio basal procedentes del yacimiento de Lo Hueco. Los especímenes fueron escaneados mediante Tomografía Axial Computarizada (TAC), que permite acceder al interior del fósil para reconstruir las cavidades internas, incluyendo el encéfalo, el oído interno, y los sistemas de senos faringotimpánicos y paranasales. Estas cavidades alojaron también algunos de los órganos sensoriales de estos animales, y mediante una serie de medidas lineales y volumétricas de estas regiones se ha podido estimar las capacidades neurosensoriales y cognitivas que tenían estos animales en vida. Estos datos se han comparado con los de varios ejemplares de crocodilios actuales de distintos tamaños, así como taxones externos a Crocodylomorpha, como aves, escamosos o tortugas. Los resultados muestran que las cavidades intracraneanas de los cocodrilomorfos son estructuras muy conservadoras, siendo las de los taxones actuales muy similares a los ya presentes en las formas basales del grupo. Sin embargo, se han encontrado algunos caracteres que parecen variar siguiendo un patrón filogenético, como la forma de la superficie dorsocaudal del cerebro, la forma de los divertículos intertimpánicos o la longitud relativa del seno faríngeo medio. Los resultados también confirman que las capacidades neurosensoriales y cognitivas presentes en las especies actuales de crocodilios, como un agudo sentido del olfato y la vista o una adaptación auditiva a frecuencias bajas, ya estaban presentes en los miembros basales de Eusuchia.
Crocodylomorpha is a very successful lineage, spanning 230 million years from its origin, in the Late Triassic, to present day. Crocodylomorph remains are common in Mesozoic and Cenozoic fossil sites across the world, showing a high diversity and abundance in these remote ancient ecosystems. The fossil site of Lo Hueco (Upper Cretaceous, Cuenca, Spain) is noteworthy because of the high number and exceptional preservation of the crocodylomorph remains found. The morphological characters in Lo Hueco specimens allow establishing three basal eusuchian morphotypes, two of them diagnosed as new endemical species: Lohuecosuchus megadontos, Agaresuchus fontisensis and an indeterminate Allodaposuchidae. The main aim of this PhD dissertation is to reconstruct and describe the inner skull cavities of several of the basal eusuchian specimens from the Lo Hueco fossil site. The specimens were scanned using CT-Technology, which allows to observe the interior of the specimen and to reconstruct its inner cavities, including the brain itself, inner ear and pharyngotympanic and paranasal sinus systems. The inner cavities also housed some of the neurosensorial organs of these animals. These regions have been linearly and volumetrically measured to estimate the neurosensorial and cognitive capabilities of these animals. These data were compared to those of several extant crocodylians of different sizes, and to those of some specimens from the outgroup of Crocodylomorpha, such as birds, squamates and turtles. The results show that inner skull cavities of crocodylomorphs are very conservative structures, being those of the extant specimens very similar to the inner skull cavities of the basal members of the group. However, some characters changes during the course of evolution following a phylogenetyc pattern, such as the shape of the caudodorsal region of the cerebrum, the shape of the intertympanic diverticula or the relative length of the median pharyngeal sinus. Our results also suggest that the neurosensory and cognitive capabilities of extant crocodylians, such as a sharp olfactory and visual acuity, or an adaptation to low-frequence hearing, were already present in early members of Eusuchia.
Crocodylomorpha is a very successful lineage, spanning 230 million years from its origin, in the Late Triassic, to present day. Crocodylomorph remains are common in Mesozoic and Cenozoic fossil sites across the world, showing a high diversity and abundance in these remote ancient ecosystems. The fossil site of Lo Hueco (Upper Cretaceous, Cuenca, Spain) is noteworthy because of the high number and exceptional preservation of the crocodylomorph remains found. The morphological characters in Lo Hueco specimens allow establishing three basal eusuchian morphotypes, two of them diagnosed as new endemical species: Lohuecosuchus megadontos, Agaresuchus fontisensis and an indeterminate Allodaposuchidae. The main aim of this PhD dissertation is to reconstruct and describe the inner skull cavities of several of the basal eusuchian specimens from the Lo Hueco fossil site. The specimens were scanned using CT-Technology, which allows to observe the interior of the specimen and to reconstruct its inner cavities, including the brain itself, inner ear and pharyngotympanic and paranasal sinus systems. The inner cavities also housed some of the neurosensorial organs of these animals. These regions have been linearly and volumetrically measured to estimate the neurosensorial and cognitive capabilities of these animals. These data were compared to those of several extant crocodylians of different sizes, and to those of some specimens from the outgroup of Crocodylomorpha, such as birds, squamates and turtles. The results show that inner skull cavities of crocodylomorphs are very conservative structures, being those of the extant specimens very similar to the inner skull cavities of the basal members of the group. However, some characters changes during the course of evolution following a phylogenetyc pattern, such as the shape of the caudodorsal region of the cerebrum, the shape of the intertympanic diverticula or the relative length of the median pharyngeal sinus. Our results also suggest that the neurosensory and cognitive capabilities of extant crocodylians, such as a sharp olfactory and visual acuity, or an adaptation to low-frequence hearing, were already present in early members of Eusuchia.
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