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Papers by JOAQUIN ARROYO-CABRALES
Open Quaternary
Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in r... more Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in re-examination of previously identified tayassuid fossils from the region. This included the recently described new genus and species of peccary, Muknalia minima, which is based on a dentary from Muknal Cave near Tulum, Quintana Roo, Mexico. Diagnostic characters of this taxon include a concave notch along the caudal edge of the ascending ramus and a ventrally directed angular process. Our assessment of the holotype indicates that these characteristics are not a reflection of the original morphology, but are instead the result of breakage and polishing of the posterior aspect of the dentary. Measurements and intact morphological features indicate the Muknal Cave specimen belongs to the extant collared peccary, Pecari tajacu.
Open Quaternary
Several years ago, a new genus and species of peccary, "Muknalia minima", was described from the ... more Several years ago, a new genus and species of peccary, "Muknalia minima", was described from the Pleistocene of Mexico. We previously examined that specimen and concluded that it was synonymous with the extant collared peccary, Pecari tajacu, but that taxonomic revision is rejected by the authors of the original study (this volume). Here, we provide further analysis of "Muknalia" and expand on previous evidence from both morphology and taphonomy that support synonymy with P. tajacu. We argue that morphological features, both in terms of size and shape, that were used to diagnose "Muknalia" all fall within the range of variation of the extant P. tajacu, or are a consequence of taphonomic modification, including human handling.
Society for Historical Archaeology, 2016
Spanish Journal of Palaeontology, 2021
En este trabajo, se discute el número máximo de especies de Equus presentes en el Pleistoceno sup... more En este trabajo, se discute el número máximo de especies de Equus presentes en el Pleistoceno superior de la localidad arqueológica-paleontológica El Cedral, San Luis Potosí. Esta localidad está situada en una zona de matorral xerófilo de la llanura mexicana y es un depósito formado dentro de antiguos manantiales, que en ciertas épocas del año debieron dar lugar a lagunas. Fue excavado durante las décadas de los 70 y 80 y se observó una clara actividad de presencia humana alrededor de hace 30.000 años AP. Se obtuvo una fauna muy rica en mamíferos, más de 5.000 huesos fósiles, que incluye especies de ratones habitantes de bosques templados y un tapir de bosque tropical que no se conoce hasta la actualidad en ninguna localidad cercana. Hemos dispuesto de una muestra importante de restos de todas las partes del esqueleto, incluidos dientes y metápodos, que nos han permitido definir los rasgos más importantes de las formas de caballo de esta localidad. Se han realizado análisis estadíst...
Current Biology, 2021
Highlights d We recovered genomic data from ancient bears directly from cave sediments d Ancient ... more Highlights d We recovered genomic data from ancient bears directly from cave sediments d Ancient Mexican black bears are ancestrally related to Eastern American black bears d The Mexican and Yukon populations of extinct giant shortfaced bears were distinct d Our results bring ancient eDNA into the era of population genomics
Geobios, 2020
Abstract Puma concolor is currently widespread in South America, but its fossil record is still p... more Abstract Puma concolor is currently widespread in South America, but its fossil record is still poorly known in the Continent, particularly in Brazil. Here we report the find of a nearly complete skeleton of P. concolor recovered from underwater Quaternary deposits at the Impossivel-Ioio Cave System, Chapada Diamantina (Bahia, Brazil). The P. concolor remains were found disarticulated but piled together; they are in general quite well preserved. Radiocarbon dating from a tooth sample (upper carnassial) indicates a Middle-Late Holocene age of ca. 4 ka BP. A series of comparative morphometric analyses suggest that the specimen is a male and shares similar size proportions to extant specimens in the region. Isotopic analyses made with a tooth sample indicate a diet largely based on C3 feeding herbivores, potentially associated to landscapes predominantly covered by Seasonally Dry Tropical Forest, similar to the Present-day Caatinga vegetation. The δ18O outcome value of −3.4‰ and the modeled puma’s negative trend in adaptability towards the present (after 6 ka) seem to be consistent with the hypothesized Middle-Holocene (∼4 ka) shift in climatic tendencies in the Brazilian Northeast from a more relatively humid environment to a drier climate with longer drought periods, presenting severe semiarid conditions somewhat similar to the precolonial conditions. Cave surroundings fit well with the description of the present progressive trend of changes in physiognomy related to land-use and associated with processes of fragmentation and desertification in the Caatinga.
Therya, 2018
Robert o Bob, como le conocimos, nació el 8 de abril de 1942 en Warren, Arkansas, en la región su... more Robert o Bob, como le conocimos, nació el 8 de abril de 1942 en Warren, Arkansas, en la región sur de los Estados Unidos de América. Sus padres fueron James Simeon Baker, quién falleció durante la II Guerra Mundial, y Laura Cooper, quién se hizo cargo de Robert y seis medios hermanos. Realizó sus estudios de bachillerato en la Ouachita Baptist University con una beca de campo y futbol, así como su licenciatura en Arkansas A&M College en Monticello, situada a unos 30 km de su ciudad natal. En 1965 se matriculó en Oklahoma State University en Stillwater, Oklahoma, para realizar la Maestría en Biología con el Dr. Bryan P. Glass. Dos años más tarde terminó y se inscribió en la University of Arizona en Tucson, donde obtuvo el doctorado bajo la dirección del Dr. E. Lendell Cockrum. En esa universidad fue compañero de otros célebres mastozoólogos, como los Dres. James L. Patton y Alfred L. Gardner. Cabe recalcar que Robert siempre sobresalió y apuntó para cosas grandes, baste señalar que sus dos posgrados los terminó en cuatro años, muy por debajo de la media nacional, además de preparar y publicar durante ese tiempo, varios trabajos y obtener financiamiento para varios de sus proyectos. Al término de sus estudios en la University of Arizona en 1967, Robert fue reclutado por J. Knox Jones, Jr. para incorporarse a Texas Tech University (TTU) donde pasaría los siguientes 48 años en el Departamento de Ciencias Biológicas. Robert fue reconocido como profesor y científico distinguido por TTU y diversas organizaciones científicas profesionales. Fue miembro activo de numerosas sociedades científicas, incluyendo haber sido el
Revista Mexicana de Biodiversidad, 2011
Quaternary Science Reviews, 2019
What is currently known about M exico paleontology and specifically the proboscideans has centere... more What is currently known about M exico paleontology and specifically the proboscideans has centered in the central and southern states, with much of the north largely unknown. Here we report on Cuvieronius (Gomphotheriidae) and Mammuthus (Elephantidae) recovered from T erapa, a Late Pleistocene site in east-central Sonora. The local fauna reflects a badlands environment along the Río Moctezuma, 183 km (114 mi) south of the Arizona border. The recovery of Bison places the locality within the Rancholabrean Land Mammal Age. Chronological analyses confirm that impounding basalt and fossiliferous sediments were deposited 43,000 to 40,000 years ago (MIS 3). Cuvieronius and Mammuthus are found throughout the stratigraphic profile. A review of Late Pleistocene collections indicates that Mammuthus, Cuvieronius, and one location of Mammut are known from Sonora. The Late Pleistocene along the T erapa river valley is reconstructed as cooler, with a more equable, less seasonal environment than today. The corridor was wetter, more tropical and included a riparian forest, ponding water, marsh, and savanna grassland. The area west of T erapa in western Sonora had a cooler summer climate, more winter rains and less summer rains. Woodlands and shrub communities occupied the upper bajadas and rocky hills, areas possibly where Mammut ranged more commonly. Valleys contained more grasslands than they do today. The environments and climates of valleys permitted Cynomys, Mammuthus, and Cuvieronius to exist over most of western Sonora where they are extinct today.
Boletín de la Sociedad Geológica Mexicana, 2009
La fauna paleoherpetológica del Pleistoceno de México se compone de 37 géneros y 58 especies regi... more La fauna paleoherpetológica del Pleistoceno de México se compone de 37 géneros y 58 especies registradas para 27 localidades diferentes; en el caso de los reptiles las tortugas son el grupo más abundante en cuanto a registros se refiere. En este trabajo se reportan y describen los restos óseos de Gopherus y Kinosternon aff. K. hirtipes/K. integrum procedentes del municipio de Santiago Chazumba, Oaxaca. El hallazgo de estas especies para el Pleistoceno de Oaxaca permite proponer un ambiente de matorral xerófilo como el existente actualmente en el Valle de Tehuacán-Cuicatlán, pero con una precipitación menor y una temperatura mayor, condiciones similares a las predominantes en el norte del país..
Quaternary Research, 2018
The Neotoma Paleoecology Database is a community-curated data resource that supports interdiscipl... more The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms...
Science (New York, N.Y.), Jan 10, 2017
On 7 December 2016, the federal government of Mexico published an Agreement listing Exotic Invasi... more On 7 December 2016, the federal government of Mexico published an Agreement listing Exotic Invasive Species for Mexico ([ 1 ][1]). However, the report contains inaccurate information about the species and ambiguous measures regarding the prevention, control, and eradication of these species.
International Journal of Morphology, 2017
RESUMEN: El charal de Toluca Chirostoma riojai es un pez de alto valor cultural e ictiológico. Lo... more RESUMEN: El charal de Toluca Chirostoma riojai es un pez de alto valor cultural e ictiológico. Los trabajos sobre esta especie se enfocan en el tipo de alimentación o forman parte de revisiones taxonómicas y son pocos los estudios sobre los cambios morfológicos durante su ontogenia. Se evaluó la figura de C. riojai mediante morfometría geométrica desde su eclosión hasta los 90 días de vida. Los ejemplares se cultivaron en condiciones controladas y fueron fijados 171 organismos pertenecientes a 11 intervalos de edad incluidos en cinco fases: embrión libre, apterolarva, pterolarva, juvenil y adulto. Se usaron seis puntos anatómicamente homólogos en una primera configuración de marcas y en una segunda se delinearon dos contornos (dorsal y ventralmente) de la región anterior. Un análisis de componentes principales mostró una fuerte diferenciación en su figura durante la transición larva-juvenil, en tanto un análisis de variables canónicas señaló diferencias significativas (ps<0.001) entre los 11 grupos de edad. La regresión lineal entre el logaritmo del tamaño centroide y las distancias procustes muestran que los organismos mantienen un cambio de figura constante hasta el término del periodo larvario, punto en el que el periodo juvenil comienza y las modificaciones en su figura disminuyen. La descripción del desarrollo temprano de C. riojai sin considerar el desarrollo de las aletas, muestra que la característica con el mayor cambio es el desplazamiento del poro anal, seguido por el alargamiento de la región cefálica. El tamaño y la figura de C. riojai durante su vida temprana pueden servir para diferenciar faces de desarrollo y ser utilizada en otras especies hermanas para evaluar si su figura es específica en cada fase. Los cambios morfológicos de C. riojai durante su vida temprana se pueden describir de forma gradual hasta el periodo larval y saltatoria en el cambio a juvenil.
Vertebrate Paleobiology and Paleoanthropology, 2017
The Pleistocene and modern mammal faunas of southern North America strongly differ in taxonomic m... more The Pleistocene and modern mammal faunas of southern North America strongly differ in taxonomic makeup, distribution, and physiognomy. The former faunal complexes are part of the ancient landscape in which early peoples may have interacted. Customarily, differences between the Pleistocene and modern faunas have been attributed to climate change or human-impact driven extinctions. Mexico’s Pleistocene mammal record is analyzed in time and space, emphasizing the study of the Rancholabrean Chronofauna, which is the most recent North American Land Mammal Age fauna. Palynological and paleosol records are reviewed as an independent check of the interpretation derived from mammals. The integration of the information provides the basis for a proposal regarding Late Pleistocene climate change trends across the country, and whether people were involved in the mammalian community response to climate change in terms of extinction or biogeographic shifting within and outside the country. This approach supports an explanation of the differences between southern North America’s Pleistocene and modern mammal faunas.
Boletin de la Sociedad Geologica Mexicana
ABSTRACT
The Southwestern Naturalist, 2014
Revista Mexicana de Biodiversidad, 2015
The Yellow-footed Gull (Larus livens) is one of the few members of the genus Larus inhabiting the... more The Yellow-footed Gull (Larus livens) is one of the few members of the genus Larus inhabiting the Gulf of California. Its breeding biology, nest phenology, and behavior have been long studied but little is known about seasonal changes in its diet. In this study, we tested if the diet of Yellow-footed Gull differed between reproductive (April and July) and non-reproductive (December). The frequency of occurrence of food items in gull's pellets and food niche breadth (FNB) and Levin's diversity (B est) indexes for each sampling period (April, July, and December), as well as Pianka's dietary overlap (O%) and Morisita's (MI) dietary similarity indices between periods were estimated. We identified 9 taxa classes, whose frequency of occurrence varied significantly between all comparisons (April and December, July and December, April and July), and between reproductive (April-July) and non-reproductive seasons. FNB and B est diversity indexes indicated that Yellow-footed Gull has a broader niche spectrum during the breeding season (April-July), while dietary overlap estimators (O% and MI) were higher between July vs. December and April vs. December, but lower in April vs. July. Results are contrasted with previous studies of gull's feeding ecology, and possible effects of local human activity are discussed.
Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years... more Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years, Sr isotopes have been used as a resourceful tracer tool in this context. A comparison of the 87Sr/86Sr ratios found in tooth enamel and in bone is performed to determine if the human skeletal remains belonged to a local or a migrant. Sr in bone approximately reflects the isotopic composition of the geological region where the person lived before death; whereas the Sr isotopic system in tooth enamel is thought to remain as a closed system and thus conserves the isotope ratio acquired during childhood. Sr isotope ratios are obtained through the geologic substrate and its overlying soil, from where an individual got hold of food and water; these ratios are in turn incorporated into the dentition and skeleton during tissue formation. In previous studies from Teotihuacan, Mexico we have shown that a three-step leaching procedure on tooth enamel samples is important to assure that only the b...
Open Quaternary
Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in r... more Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in re-examination of previously identified tayassuid fossils from the region. This included the recently described new genus and species of peccary, Muknalia minima, which is based on a dentary from Muknal Cave near Tulum, Quintana Roo, Mexico. Diagnostic characters of this taxon include a concave notch along the caudal edge of the ascending ramus and a ventrally directed angular process. Our assessment of the holotype indicates that these characteristics are not a reflection of the original morphology, but are instead the result of breakage and polishing of the posterior aspect of the dentary. Measurements and intact morphological features indicate the Muknal Cave specimen belongs to the extant collared peccary, Pecari tajacu.
Open Quaternary
Several years ago, a new genus and species of peccary, "Muknalia minima", was described from the ... more Several years ago, a new genus and species of peccary, "Muknalia minima", was described from the Pleistocene of Mexico. We previously examined that specimen and concluded that it was synonymous with the extant collared peccary, Pecari tajacu, but that taxonomic revision is rejected by the authors of the original study (this volume). Here, we provide further analysis of "Muknalia" and expand on previous evidence from both morphology and taphonomy that support synonymy with P. tajacu. We argue that morphological features, both in terms of size and shape, that were used to diagnose "Muknalia" all fall within the range of variation of the extant P. tajacu, or are a consequence of taphonomic modification, including human handling.
Society for Historical Archaeology, 2016
Spanish Journal of Palaeontology, 2021
En este trabajo, se discute el número máximo de especies de Equus presentes en el Pleistoceno sup... more En este trabajo, se discute el número máximo de especies de Equus presentes en el Pleistoceno superior de la localidad arqueológica-paleontológica El Cedral, San Luis Potosí. Esta localidad está situada en una zona de matorral xerófilo de la llanura mexicana y es un depósito formado dentro de antiguos manantiales, que en ciertas épocas del año debieron dar lugar a lagunas. Fue excavado durante las décadas de los 70 y 80 y se observó una clara actividad de presencia humana alrededor de hace 30.000 años AP. Se obtuvo una fauna muy rica en mamíferos, más de 5.000 huesos fósiles, que incluye especies de ratones habitantes de bosques templados y un tapir de bosque tropical que no se conoce hasta la actualidad en ninguna localidad cercana. Hemos dispuesto de una muestra importante de restos de todas las partes del esqueleto, incluidos dientes y metápodos, que nos han permitido definir los rasgos más importantes de las formas de caballo de esta localidad. Se han realizado análisis estadíst...
Current Biology, 2021
Highlights d We recovered genomic data from ancient bears directly from cave sediments d Ancient ... more Highlights d We recovered genomic data from ancient bears directly from cave sediments d Ancient Mexican black bears are ancestrally related to Eastern American black bears d The Mexican and Yukon populations of extinct giant shortfaced bears were distinct d Our results bring ancient eDNA into the era of population genomics
Geobios, 2020
Abstract Puma concolor is currently widespread in South America, but its fossil record is still p... more Abstract Puma concolor is currently widespread in South America, but its fossil record is still poorly known in the Continent, particularly in Brazil. Here we report the find of a nearly complete skeleton of P. concolor recovered from underwater Quaternary deposits at the Impossivel-Ioio Cave System, Chapada Diamantina (Bahia, Brazil). The P. concolor remains were found disarticulated but piled together; they are in general quite well preserved. Radiocarbon dating from a tooth sample (upper carnassial) indicates a Middle-Late Holocene age of ca. 4 ka BP. A series of comparative morphometric analyses suggest that the specimen is a male and shares similar size proportions to extant specimens in the region. Isotopic analyses made with a tooth sample indicate a diet largely based on C3 feeding herbivores, potentially associated to landscapes predominantly covered by Seasonally Dry Tropical Forest, similar to the Present-day Caatinga vegetation. The δ18O outcome value of −3.4‰ and the modeled puma’s negative trend in adaptability towards the present (after 6 ka) seem to be consistent with the hypothesized Middle-Holocene (∼4 ka) shift in climatic tendencies in the Brazilian Northeast from a more relatively humid environment to a drier climate with longer drought periods, presenting severe semiarid conditions somewhat similar to the precolonial conditions. Cave surroundings fit well with the description of the present progressive trend of changes in physiognomy related to land-use and associated with processes of fragmentation and desertification in the Caatinga.
Therya, 2018
Robert o Bob, como le conocimos, nació el 8 de abril de 1942 en Warren, Arkansas, en la región su... more Robert o Bob, como le conocimos, nació el 8 de abril de 1942 en Warren, Arkansas, en la región sur de los Estados Unidos de América. Sus padres fueron James Simeon Baker, quién falleció durante la II Guerra Mundial, y Laura Cooper, quién se hizo cargo de Robert y seis medios hermanos. Realizó sus estudios de bachillerato en la Ouachita Baptist University con una beca de campo y futbol, así como su licenciatura en Arkansas A&M College en Monticello, situada a unos 30 km de su ciudad natal. En 1965 se matriculó en Oklahoma State University en Stillwater, Oklahoma, para realizar la Maestría en Biología con el Dr. Bryan P. Glass. Dos años más tarde terminó y se inscribió en la University of Arizona en Tucson, donde obtuvo el doctorado bajo la dirección del Dr. E. Lendell Cockrum. En esa universidad fue compañero de otros célebres mastozoólogos, como los Dres. James L. Patton y Alfred L. Gardner. Cabe recalcar que Robert siempre sobresalió y apuntó para cosas grandes, baste señalar que sus dos posgrados los terminó en cuatro años, muy por debajo de la media nacional, además de preparar y publicar durante ese tiempo, varios trabajos y obtener financiamiento para varios de sus proyectos. Al término de sus estudios en la University of Arizona en 1967, Robert fue reclutado por J. Knox Jones, Jr. para incorporarse a Texas Tech University (TTU) donde pasaría los siguientes 48 años en el Departamento de Ciencias Biológicas. Robert fue reconocido como profesor y científico distinguido por TTU y diversas organizaciones científicas profesionales. Fue miembro activo de numerosas sociedades científicas, incluyendo haber sido el
Revista Mexicana de Biodiversidad, 2011
Quaternary Science Reviews, 2019
What is currently known about M exico paleontology and specifically the proboscideans has centere... more What is currently known about M exico paleontology and specifically the proboscideans has centered in the central and southern states, with much of the north largely unknown. Here we report on Cuvieronius (Gomphotheriidae) and Mammuthus (Elephantidae) recovered from T erapa, a Late Pleistocene site in east-central Sonora. The local fauna reflects a badlands environment along the Río Moctezuma, 183 km (114 mi) south of the Arizona border. The recovery of Bison places the locality within the Rancholabrean Land Mammal Age. Chronological analyses confirm that impounding basalt and fossiliferous sediments were deposited 43,000 to 40,000 years ago (MIS 3). Cuvieronius and Mammuthus are found throughout the stratigraphic profile. A review of Late Pleistocene collections indicates that Mammuthus, Cuvieronius, and one location of Mammut are known from Sonora. The Late Pleistocene along the T erapa river valley is reconstructed as cooler, with a more equable, less seasonal environment than today. The corridor was wetter, more tropical and included a riparian forest, ponding water, marsh, and savanna grassland. The area west of T erapa in western Sonora had a cooler summer climate, more winter rains and less summer rains. Woodlands and shrub communities occupied the upper bajadas and rocky hills, areas possibly where Mammut ranged more commonly. Valleys contained more grasslands than they do today. The environments and climates of valleys permitted Cynomys, Mammuthus, and Cuvieronius to exist over most of western Sonora where they are extinct today.
Boletín de la Sociedad Geológica Mexicana, 2009
La fauna paleoherpetológica del Pleistoceno de México se compone de 37 géneros y 58 especies regi... more La fauna paleoherpetológica del Pleistoceno de México se compone de 37 géneros y 58 especies registradas para 27 localidades diferentes; en el caso de los reptiles las tortugas son el grupo más abundante en cuanto a registros se refiere. En este trabajo se reportan y describen los restos óseos de Gopherus y Kinosternon aff. K. hirtipes/K. integrum procedentes del municipio de Santiago Chazumba, Oaxaca. El hallazgo de estas especies para el Pleistoceno de Oaxaca permite proponer un ambiente de matorral xerófilo como el existente actualmente en el Valle de Tehuacán-Cuicatlán, pero con una precipitación menor y una temperatura mayor, condiciones similares a las predominantes en el norte del país..
Quaternary Research, 2018
The Neotoma Paleoecology Database is a community-curated data resource that supports interdiscipl... more The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms...
Science (New York, N.Y.), Jan 10, 2017
On 7 December 2016, the federal government of Mexico published an Agreement listing Exotic Invasi... more On 7 December 2016, the federal government of Mexico published an Agreement listing Exotic Invasive Species for Mexico ([ 1 ][1]). However, the report contains inaccurate information about the species and ambiguous measures regarding the prevention, control, and eradication of these species.
International Journal of Morphology, 2017
RESUMEN: El charal de Toluca Chirostoma riojai es un pez de alto valor cultural e ictiológico. Lo... more RESUMEN: El charal de Toluca Chirostoma riojai es un pez de alto valor cultural e ictiológico. Los trabajos sobre esta especie se enfocan en el tipo de alimentación o forman parte de revisiones taxonómicas y son pocos los estudios sobre los cambios morfológicos durante su ontogenia. Se evaluó la figura de C. riojai mediante morfometría geométrica desde su eclosión hasta los 90 días de vida. Los ejemplares se cultivaron en condiciones controladas y fueron fijados 171 organismos pertenecientes a 11 intervalos de edad incluidos en cinco fases: embrión libre, apterolarva, pterolarva, juvenil y adulto. Se usaron seis puntos anatómicamente homólogos en una primera configuración de marcas y en una segunda se delinearon dos contornos (dorsal y ventralmente) de la región anterior. Un análisis de componentes principales mostró una fuerte diferenciación en su figura durante la transición larva-juvenil, en tanto un análisis de variables canónicas señaló diferencias significativas (ps<0.001) entre los 11 grupos de edad. La regresión lineal entre el logaritmo del tamaño centroide y las distancias procustes muestran que los organismos mantienen un cambio de figura constante hasta el término del periodo larvario, punto en el que el periodo juvenil comienza y las modificaciones en su figura disminuyen. La descripción del desarrollo temprano de C. riojai sin considerar el desarrollo de las aletas, muestra que la característica con el mayor cambio es el desplazamiento del poro anal, seguido por el alargamiento de la región cefálica. El tamaño y la figura de C. riojai durante su vida temprana pueden servir para diferenciar faces de desarrollo y ser utilizada en otras especies hermanas para evaluar si su figura es específica en cada fase. Los cambios morfológicos de C. riojai durante su vida temprana se pueden describir de forma gradual hasta el periodo larval y saltatoria en el cambio a juvenil.
Vertebrate Paleobiology and Paleoanthropology, 2017
The Pleistocene and modern mammal faunas of southern North America strongly differ in taxonomic m... more The Pleistocene and modern mammal faunas of southern North America strongly differ in taxonomic makeup, distribution, and physiognomy. The former faunal complexes are part of the ancient landscape in which early peoples may have interacted. Customarily, differences between the Pleistocene and modern faunas have been attributed to climate change or human-impact driven extinctions. Mexico’s Pleistocene mammal record is analyzed in time and space, emphasizing the study of the Rancholabrean Chronofauna, which is the most recent North American Land Mammal Age fauna. Palynological and paleosol records are reviewed as an independent check of the interpretation derived from mammals. The integration of the information provides the basis for a proposal regarding Late Pleistocene climate change trends across the country, and whether people were involved in the mammalian community response to climate change in terms of extinction or biogeographic shifting within and outside the country. This approach supports an explanation of the differences between southern North America’s Pleistocene and modern mammal faunas.
Boletin de la Sociedad Geologica Mexicana
ABSTRACT
The Southwestern Naturalist, 2014
Revista Mexicana de Biodiversidad, 2015
The Yellow-footed Gull (Larus livens) is one of the few members of the genus Larus inhabiting the... more The Yellow-footed Gull (Larus livens) is one of the few members of the genus Larus inhabiting the Gulf of California. Its breeding biology, nest phenology, and behavior have been long studied but little is known about seasonal changes in its diet. In this study, we tested if the diet of Yellow-footed Gull differed between reproductive (April and July) and non-reproductive (December). The frequency of occurrence of food items in gull's pellets and food niche breadth (FNB) and Levin's diversity (B est) indexes for each sampling period (April, July, and December), as well as Pianka's dietary overlap (O%) and Morisita's (MI) dietary similarity indices between periods were estimated. We identified 9 taxa classes, whose frequency of occurrence varied significantly between all comparisons (April and December, July and December, April and July), and between reproductive (April-July) and non-reproductive seasons. FNB and B est diversity indexes indicated that Yellow-footed Gull has a broader niche spectrum during the breeding season (April-July), while dietary overlap estimators (O% and MI) were higher between July vs. December and April vs. December, but lower in April vs. July. Results are contrasted with previous studies of gull's feeding ecology, and possible effects of local human activity are discussed.
Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years... more Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years, Sr isotopes have been used as a resourceful tracer tool in this context. A comparison of the 87Sr/86Sr ratios found in tooth enamel and in bone is performed to determine if the human skeletal remains belonged to a local or a migrant. Sr in bone approximately reflects the isotopic composition of the geological region where the person lived before death; whereas the Sr isotopic system in tooth enamel is thought to remain as a closed system and thus conserves the isotope ratio acquired during childhood. Sr isotope ratios are obtained through the geologic substrate and its overlying soil, from where an individual got hold of food and water; these ratios are in turn incorporated into the dentition and skeleton during tissue formation. In previous studies from Teotihuacan, Mexico we have shown that a three-step leaching procedure on tooth enamel samples is important to assure that only the b...