Ontogeny, evolution and palaeogeographic distribution of the world's largest ammonite Parapuzosia (P.) seppenradensis (Landois, 1895).

The world's largest ammonite, Parapuzosia (P.) seppenradensis (Landois, 1895), fascinated the world ever since the discovery, in 1895, of a specimen of 1.74 metres (m) diameter near Seppenrade in Westfalia, Germany, but subsequent findings of the taxon are exceedingly rare and its systematic position remains enigmatic. Here we revise the historical specimens and document abundant new material from England and Mexico. Our study comprises 154 specimens of large (< 1 m diameter) to giant (> 1m diameter) Parapuzosia from the Santonian and lower Campanian, mostly with stratigraphic information. High-resolution integrated stratigraphy allows for precise cross-Atlantic correlation of the occurrences. Our specimens were analysed regarding morphometry, growth stages and stratigraphic occurrence wherever possible. Our analysis provides insight into the ontogeny of Parapuzosia (P.) seppenradensis and into the evolution of this species from its potential ancestor P. (P.) leptophylla Sharpe, 1857. The latter grew to shell diameters of about 1 m and was restricted to Europe in the early Santonian, but it reached the Gulf of Mexico during the late Santonian. P. (P.) seppenradensis first appears in the uppermost Santonian- earliest Campanian on both sides of the Atlantic. Initially, it also reached diameters of about 1 m, but gradual evolutionary increase in size is seen in the middle early Campanian to diameters of 1.5 to 1.8 m. P. (P.) seppenradensis is characterized by five ontogenetic growth stages and by size dimorphism. We therefore here include the many historic species names used in the past to describe the morphological and size variability of the taxon. The concentration of adult shells in small geographic areas and scarcity of Parapuzosia in nearby coeval outcrop regions may point to a monocyclic, possibly even semelparous reproduction strategy in this giant cephalopod. Its gigantism exceeds a general trend of size increase in late Cretaceous cephalopods. Whether the coeval increase in size of mosasaurs, the top predators in Cretaceous seas, caused ecological pressure on Parapuzosia towards larger diameters remains unclear.

New evidence for an early settlement of the Yucatán Peninsula, Mexico: The Chan Hol 3 woman and her meaning for the Peopling of the Americas.

Human presence on the Yucatán Peninsula reaches back to the Late Pleistocene. Osteological evidence comes from submerged caves and sinkholes (cenotes) near Tulum in the Mexican state of Quintana Roo. Here we report on a new skeleton discovered by us in the Chan Hol underwater cave, dating to a minimum age of 9.9±0.1 ky BP based on 230Th/U-dating of flowstone overlying and encrusting human phalanges. This is the third Paleoindian human skeleton with mesocephalic cranial characteristics documented by us in the cave, of which a male individual named Chan Hol 2 described recently is one of the oldest human skeletons found on the American continent. The new discovery emphasizes the importance of the Chan Hol cave and other systems in the Tulum area for understanding the early peopling of the Americas. The new individual, here named Chan Hol 3, is a woman of about 30 years of age with three cranial traumas. There is also evidence for a possible trepanomal bacterial disease that caused severe alteration of the posterior parietal and occipital bones of the cranium. This is the first time that the presence of such disease is reported in a Paleoindian skeleton in the Americas. All ten early skeletons found so far in the submerged caves from the Yucatán Peninsula have mesocephalic cranial morphology, different to the dolicocephalic morphology for Paleoindians from Central Mexico with equivalent dates. This supports the presence of two morphologically different Paleoindian populations for Mexico, coexisting in different geographical areas during the Late Pleistocene-Early Holocene.

Morphological variation of the early human remains from Quintana Roo, Yucatán Peninsula, Mexico: Contributions to the discussions about the settlement of the Americas.

The human settlement of the Americas has been a topic of intense debate for centuries, and there is still no consensus on the tempo and mode of early human dispersion across the continent. When trying to explain the biological diversity of early groups across North, Central and South America, studies have defended a wide range of dispersion models that tend to oversimplify the diversity observed across the continent. In this study, we aim to contribute to this debate by exploring the cranial morphological affinities of four late Pleistocene/early Holocene specimens recovered from the caves of Quintana Roo, Mexico. The four specimens are among the earliest human remains known in the continent and permit the contextualization of biological diversity present during the initial millennia of human presence in the Americas. The specimens were compared to worldwide reference series through geometric morphometric analyses of 3D anatomical landmarks. Morphological data were analyzed through exploratory visual multivariate analyses and multivariate classification based on Mahalanobis distances. The results show very different patterns of morphological association for each Quintana Roo specimen, suggesting that the early populations of the region already shared a high degree of morphological diversity. This contrasts with previous studies of South American remains and opens the possibility that the initial populations of North America already had a high level of morphological diversity, which was reduced as populations dispersed into the southern continent. As such, the study of these rare remains illustrates that we are probably still underestimating the biological diversity of early Americans.

Complicaciones clínicas y resultados en pacientes con múltiples sesiones de litotripsia extracorporal por ondas de choque / Clinical complications and results in patients treated with multiple extracorporal shock-wave lithotripsy sessions

La litotripsia extracorporal por ondas de choque es un prodecimiento aceptado por su seguridad y eficacia para el tratamiento de los pacientes con litiasis renal y ureteral. En el Hospital de Especialidades del Centro Médico Nacional de Occidente del IMSS se estudiaron 161 pacientes tratados mediante litotripsia extracorporal por ondas de choque (LEOCH). El promedio de edad fue de 44 años, con límites de 15 a 79. Del total de pacientes 72 (44.7 por ciento) eran mujeres y 89 (55.3 por ciento) varones. No se utilizó anestesia para el procedimiento, y los pacientes fueron ambulatorios. El análisis se centró fundamentalmente en tamaño de los cálculos, fragmentación de los mismos, drenaje de los fragmentos, influencia de la dilatación de los sistemas colectores en la expulsión de cálculos, número de pulsos administrados, y complicaciones entre sesiones y al final del tratamiento. La información se procesó en el programa EPI INFO versión 6 para aplicar medidas de tendencia central y dispersión, prueba de xi cuadrada, análisis estratificado de Mantel-Haenszel y ANOVA. Se obtuvieron los mejores resultados en lo referente a fragmentación con los cálculos de 6 a 30 mm de diámetro, en comparación con los menores de 5 mm y los mayores de 31 mm. La expulsión de fragmentos en pacientes con dilatación de sistemas colectores o sin ella no puso de manifiesto una diferencia estadísticamente significativa (p= 0.23). Se logró la fragmentación en pacientes con cálculos únicos o múltiples en relación directamente proporcional a la dimensión total del cálculo único o mayor con intervalos de confianza del 95 por ciento de 0.37 (0.12 o 0.98). El número de pulsos aplicados fue similar para los cálculos que se fragmentaron, y la diferencia la hizo el tamaño. Los cálculos se fragmentaron en 68 por ciento de los pacientes, y se expulsaron con excelentes resultados en 55 por ciento, buenos en 30 por ciento y malos en 26 por ciento. Las complicaciones clínicamente identificadas son similares a las informadas en otras series