Paleontoriano

Investigadores de la Universidad Monash, Australia, dirigidos por el Dr. Jeffrey Stilwell y el Dr. Chris Mays hallaron las primeras plantas con flores e insectos raros conservados en una formación rocosa.
Según los expertos, estos fósiles datan del período Cretácico (145 a 65 millones de años) cuando las diferentes especies de dinosaurios, incluyendo monstruos como T-Rex vagaban por la Tierra.

El descubrimiento revela que las especies existieron durante el período Cretácico. Continentes, incluyendo Nueva Zelanda, África, Antártida, India, Australia y América del Sur fueron parte de una masa de tierra austral llamada Gondwana, que era una sección del antiguo supercontinente Pangea.
La temperatura en este período fue extremadamente caliente. Alrededor de 110 a 90 millones de años atrás, las emisiones volcánicas submarinas de CO2 aumentaron las concentraciones de CO2 en la atmósfera.

Este incremento causó la elevación del nivel del mar hasta 200 metros. La acumulación del CO2 se prolongó durante 10 millones de años, fue durante este tiempo que las plantas con flores evolucionaron para hacer frente a condiciones de invernadero y comenzó a extenderse por el paisaje, proporcionando una fuente de alimento para los dinosaurios.

El bosque fósil es el primer registro de vida que pertenece al período Cretácico encontrado cerca del Polo Sur, lo que revela la vida pretérita cerca de la Antártida.
"Hasta ahora no había ningún análogo moderno de este tipo de bosques preservados tan cerca al Polo Sur, aproximadamente a 1200 kilómetros", dijo el Dr. Mays.

"El descubrimiento muestra un tipo completamente diferente de ecosistema hace aproximadamente 100 millón de años, revelando las primeras ideas sobre estrategias específicas de que estas plantas y animales han evolucionado para hacer frente a condiciones extremas de efecto invernadero, y meses de luz y oscuridad", concluyó.

Dilophosaurus

Oviraptor

Tsintaosaurus

Un estudio publicado en el Journal of Experimental Biology llamado “Refuerzo protector del puño humano y la evolución de la mano homínida” sugiere que nuestras manos no sólo evolucionaron para tener una mayor destreza manual para fabricar herramientas o crear arte, sino que también para que pudiéramos empuñarla y pelear con otros seres humanos.

“Hemos subestimado el rol de nuestra agresividad en los estudios de nuestra evolución“, afirma el profesor de biología de la Universidad de Utah y autor principal del estudio, David Carrier. “Hay personas que no les gusta esta idea, pero está claro que comparado con otros mamíferos, los grandes simios son un grupo relativamente agresivo, con muchas peleas y violencia, y eso nos incluye a nosotros“.

Carrier afirma que las manos humanas evolucionaron para tener más destreza, pero añade que “las proporciones de nuestra mano también nos permite empuñarla (…) éstas habrían evolucionado en respuesta a la selección natural por nuestras habilidades para pelear, además de nuestra destreza“.
Los dedos y manos largas de los simios evolucionaron para permitirles escalar árboles, por lo que cuando nuestros ancestros se bajaron de éstos, desapareció como factor en la selección natural, pasando a predominar la manipulación de objetos, lo que cambió las manos de nuestros ancestros.

Eso si, Carrier afirma que si la destreza manual hubiera sido el único factor en la evolución de nuestras manos, los humanos tendríamos pulgares más largos sin que se nos hubieran achicado los dedos y las palmas de las manos. “Sólo hay una forma de empuñar una mano: Que durante nuestra evolución la palma y los dedos se acorten al mismo tiempo que se alargue nuestro pulgar“.

Fuente:
De algún lado

A group of 30 students in Bursa have allegedly vandalized a fossil exhibition at Uludağ University, beating three security guards, breaking into the exhibition and damaging the fossils.
The students recorded the attack, shouting slogans and taking photos with the damaged fossils, which they claim are fake. The exhibit has been organized by an anti-evolution group that claims the fossils on display prove that life forms have not changed over thousands of years, while others doubt the authenticity of the fossils.

Police have analyzed the area and taken fingerprints. Speaking to Anatolia news agency, exhibition official Hakan İyihuylu said: “[On Dec. 21] we opened this exhibition. At noon a group of students came, shouting leftist political slogans. They did not even talk to us. They just entered the exhibition and damaged the pieces. People who damaged the artifacts are supporting Darwinism and are leftists. They call themselves volunteers.”

Noting that all the fossils have been certified as real, İyihuylu said the team is not publicly displaying the fossils due to security reasons despite their wish to do so.
The police are still trying to locate the assailants.

In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.

That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.
The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.

"The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity -- or some combination of the two -- killed off most of the large mammals," said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study. "In the case of the great cats, we expect that it would have been increasingly difficult for them to find prey, especially if had to compete with humans. We know that when food becomes scarce, carnivores like the great cats tend to consume more of the carcasses they kill. If they spent more time chomping on bones, it should cause detectable changes in the wear patterns on their teeth."

In 1993, Blaire Van Valkenburgh at UCLA published a paper on tooth breakage in large carnivores in the late Pleistocene. Analyzing teeth of American lions, saber-tooth cats, dire wolves and coyotes from La Brea, she found that they had approximately three times the number of broken teeth of contemporary predators and concluded, ." ..these findings suggest that these species utilized carcasses more fully and likely competed more intensely for food than present-day large carnivores."
The latest study uses a new technique, called dental microwear texture analysis (DMTA), developed by co-author Peter Ungar at the University of Arkansas. It uses a confocal microscope to produce a three-dimensional image of the surface of a tooth. The image is then analyzed for microscopic wear patterns. Chowing down on red meat produces small parallel scratches. Chomping on bones adds larger, deeper pits. Previous methods of dental wear analysis relied on researchers to identify and count these different types of features. DMTA relies on automated software and is considered more accurate because it reduces the possibility of observer bias.

DeSantis and Ungar, with the assistance of Blaine Schubert from East Tennessee State University and Jessica Scott from the University of Arkansas, applied DMTA to the fossil teeth of 15 American lions (Panthera atrox) and 15 saber-tooth cats (Smilodon fatalis) recovered from the La Brea tar pits in Los Angeles.
Their analysis revealed that the wear pattern on the teeth of the American lion most closely resembled those of the present-day cheetah, which actively avoids bones when it feeds. Similarly, the saber-tooth cat's wear pattern most closely resembled those of the present-day African lion, which indulges in some bone crushing when it eats. (This differs from a previous microwear study using a different technique that concluded saber-tooth cats avoided bone to a far greater extent.)
The researchers examined how these patterns changed over time by selecting specimens from tar pits of different ages, ranging from about 35,000 to 11,500 years ago. They did not find any evidence that the two carnivores increased their "utilization" of carcasses throughout this period. If anything, their analysis suggests that the proportion of the carcasses that both kinds of cats consumed actually declined toward the end.

The researchers acknowledge the high rate of tooth breakage reported in the previous study, but they argue that it is more likely the result of increased breakage when taking down prey instead of when feeding.
"Teeth can break from the stress of chewing bone but they can also break when the carnivores take down prey," DeSantis pointed out. Species like hyenas that regularly chew and crack bones of their kills are as likely to break the rear teeth they use for chewing as their front canines. Species like the cheetah, however, which avoid bones during feeding are twice as likely to break canines than rear teeth. This suggests that they are more likely to break canines when pulling down prey.
The researchers report that previous examinations of the jaws of the American lions and saber-tooth cats from this period found that they have more than three times as many broken canines and interpret this as additional evidence that supports their conclusion that most of the excess tooth breakage occurred during capture instead of feeding.

In addition, the researchers argue that the large size of the extinct carnivores and their prey can help explain the large number of broken teeth. The saber-toothed cats were about the size of today's African lion and the American lion was about 25 percent larger. The animals that they preyed upon likely included mammoths, four-ton giant ground sloths and 3,500-pound bison.
Larger teeth break more easily than smaller teeth. So larger carnivores are likely to break more canine teeth when attempting to take down larger prey, the researchers argue. They cite a study that modeled the strength of canine teeth that found the canines of a predator the size of fox can support more than seven times its weight before breaking while a predator the size of lion can only support about four times its weight and the curved teeth of the saber-toothed cats can only support about twice its weight.

"The net result of our study is to raise questions about the reigning hypothesis that "tough times" during the late Pleistocene contributed to the gradual extinction of large carnivores," DeSantis summarized. "While we can not determine the exact cause of their demise, it is unlikely that the extinction of these cats was a result of gradually declining prey (due either to changing climates or human competition) because their teeth tell us that these cats were not desperately consuming entire carcasses, as we had expected, and instead seemed to be living the 'good life' during the late Pleistocene, at least up until the very end."

Source:
http://www.sciencedaily.com/releases/2012/12/121226222838.htm

"The landscape early humans were inhabiting transitioned rapidly back and forth between a closed woodland and an open grassland about five to six times during a period of 200,000 years," said Clayton Magill, graduate student in geosciences at Penn State. "These changes happened very abruptly, with each transition occurring over hundreds to just a few thousand years."
According to Katherine Freeman, professor of geosciences, Penn State, the current leading hypothesis suggests that evolutionary changes among humans during the period the team investigated were related to a long, steady environmental change or even one big change in climate.
"There is a view this time in Africa was the 'Great Drying,' when the environment slowly dried out over 3 million years," she said. "But our data show that it was not a grand progression towards dry; the environment was highly variable."
According to Magill, many anthropologists believe that variability of experience can trigger cognitive development.

"Early humans went from having trees available to having only grasses available in just 10 to 100 generations, and their diets would have had to change in response," he said. "Changes in food availability, food type, or the way you get food can trigger evolutionary mechanisms to deal with those changes. The result can be increased brain size and cognition, changes in locomotion and even social changes -- how you interact with others in a group. Our data are consistent with these hypotheses. We show that the environment changed dramatically over a short time, and this variability coincides with an important period in our human evolution when the genus Homo was first established and when there was first evidence of tool use."
The researchers -- including Gail Ashley, professor of earth and planetary sciences, Rutgers University -- examined lake sediments from Olduvai Gorge in northern Tanzania. They removed the organic matter that had either washed or was blown into the lake from the surrounding vegetation, microbes and other organisms 2 million years ago from the sediments. In particular, they looked at biomarkers -- fossil molecules from ancient organisms -- from the waxy coating on plant leaves.
"We looked at leaf waxes because they're tough, they survive well in the sediment," said Freeman.
The team used gas chromatography and mass spectrometry to determine the relative abundances of different leaf waxes and the abundance of carbon isotopes for different leaf waxes. The data enabled them to reconstruct the types of vegetation present in the Olduvai Gorge area at very specific time intervals.

The results showed that the environment transitioned rapidly back and forth between a closed woodland and an open grassland.
To find out what caused this rapid transitioning, the researchers used statistical and mathematical models to correlate the changes they saw in the environment with other things that may have been happening at the time, including changes in the Earth's movement and changes in sea-surface temperatures.
"The orbit of the Earth around the sun slowly changes with time," said Freeman. "These changes were tied to the local climate at Olduvai Gorge through changes in the monsoon system in Africa. Slight changes in the amount of sunshine changed the intensity of atmospheric circulation and the supply of water. The rain patterns that drive the plant patterns follow this monsoon circulation. We found a correlation between changes in the environment and planetary movement."
The team also found a correlation between changes in the environment and sea-surface temperature in the tropics.

"We find complementary forcing mechanisms: one is the way Earth orbits, and the other is variation in ocean temperatures surrounding Africa," Freeman said. The researchers recently published their results in the Proceedings of the National Academy of Sciences along with another paper in the same issue that builds on these findings. The second paper shows that rainfall was greater when there were trees around and less when there was a grassland.
"The research points to the importance of water in an arid landscape like Africa," said Magill. "The plants are so intimately tied to the water that if you have water shortages, they usually lead to food insecurity.
"Together, these two papers shine light on human evolution because we now have an adaptive perspective. We understand, at least to a first approximation, what kinds of conditions were prevalent in that area and we show that changes in food and water were linked to major evolutionary changes."

Source:
www.sciencedaily.com/releases/2012/12/121226080906.htm 

Craneo del Dinosaurio

Researchers diving off the coast of Georgia may have found the remains of an Atlantic gray whale, a relic of a population that was hunted to extinction by the 18th century.
But this particular specimen died long before whalers became a threat. Carbon dating showed that the fossil, a left jawbone, is about 36,000 years old. 

The big bone was first discovered along with two badly eroded vertebrae near Gray's Reef National Marine Sanctuary about 20 miles (32 kilometers) off southeast Georgia in 2008. It took the researchers two years to pull out all of the pieces of the fossil, which was embedded in layers of shell and sand 70 feet (21 meters) below the surface. The jawbone was recovered in sections and measures 5 feet (1.5 m) in length.
The researchers say the bone is clearly from a baleen whale — or whales that use baleen plates in their mouths to filter meals of tiny organisms out of seawater — and looks very similar to that of the gray whale, Eschrichtius robustus. This species is only locally extinct. Gray whales can be found today in quite strong numbers, but only in the Pacific Ocean, and even these had once teetered on the brink of extinction during eras when the whaling industry reigned. 

Scientists previously believed that the Atlantic gray whale had been a distinct species. But recent research has shown these vanished whales and the living ones in the Pacific are actually one in the same.
"The California grays looked exactly like the bones that were dug up in Scandinavia back in the 19th century," Ervan Garrison, a geoarchaeology professor at the University of Georgia, said in a statement, describing it as "one of the first instances where a living species was named based on the fossil evidence." 

The new specimen's age of approximately 36,570 years old makes it one of the oldest fossil finds in the western Atlantic basin, the researchers say. And if the find indeed represents a Pleistocene-age gray whale, its oldest counterpart is a specimen found on the southern North Sea dating to 42,800 years ago.
The research was detailed online last month in the journal Paleontologica Electronica.WTF!

Los neandertales eran soberbios cazadores que se atrevían con rinocerontes, uros, caballos.... “Eran carnívoros. Y tenemos que investigar el componente vegetal de su dieta”, sugiere Arsuaga, señalando que en Europa en el territorio de los neandertales solo hay frutos disponibles para comer a finales de verano y otoño. Por eso no hay apenas monos, excepto macacos, que son pequeños, precisan pocas calorías y comen hojas. “Los ecosistemas en Europa son estacionales porque el clima es estacional y, en período de glaciación la situación es aún más extrema. Los neandertales tuvieron que ser carnívoros”, añade el paleontólogo.

Los homínidos primitivos, como el resto de los primates, vivieron en África, en el bosque tropical y subtropical, cuyos ecosistemas proporcionan alimento constante todo el año, argumenta Arsuaga, quien concluye: “Hubo que aprender a cazar para salir del trópico y extenderse por Eurasia, por eso tardaron tanto los homínidos en lograr desligarse de los ecosistemas tropicales”.

Los neandertales, que son ya muy avanzados en comparación con los australopitecos africanos —que comían raíces, frutas o, en todo caso, carroña—, practicaban caza mayor. Pero para vivir de esas capturas hace falta dominar un salto tecnológico muy importante que es hacerse herramientas para cortar y preparar las presas. “Un uro o un rinoceronte no los puedes comer a mordiscos, con la piel tan gruesa que tienen; hace falta cortar y trocear las piezas. No solo eran unos expertos cazadores; también dominaban la fabricación de piedras de filo para desgarrar y raederas para el cuero y la madera”, apunta Enrique Baquedano. “En estos yacimientos de Pinilla del Valle hemos encontrado miles de herramientas de piedra”, añade.

Pero los neandertales comieron algún tipo de vegetales. Arsuaga explica que una investigadora ha descubierto que el sarro de los dientes conserva almidón vegetal y así ha podido identificar las plantas que comían los individuos prehistóricos. “Los neandertales de Bélgica, en la época glacial, según indican los fósiles, comían raíces de junco, y los de Irak, dátiles. Estoy convencido de que los nuestros comían bellotas”, comenta.

Y así termina nuestro corto recorrido por este maravilloso descubrimiento, quien sabe que otras sorpresas este valle nos dará pronto!

A research team led by Willy Tegel and Dr. Dietrich Hakelberg from the Institute of Forest Growth of the University of Freiburg has succeeded in precisely dating four water wells built by the first Central European agricultural civilization with the help of dendrochronology or growth ring dating. The wells were excavated at settlements in the Greater Leipzig region and are the oldest known timber constructions in the world. They were built by the Linear Pottery culture, which existed from roughly 5600 to 4900 BC.

The team's findings, which have been published in the international scientific journal PLoS ONE, afford new insight into prehistoric technology. The study was conducted by archaeologists and dendrochronologists from the Institute of Forest Growth in Freiburg, the Archaeological Heritage Office of Saxony in Dresden, and the Swiss Federal Research Institute WSL in Birmensdorf, Switzerland.

The four early Neolithic wells were constructed from oak wood. In addition to the timber, many other waterlogged organic materials, such as plant remains, wooden artifacts, bark vessels, and bast fiber cords, as well as an array of richly decorated ceramic vessels, have survived for millennia hermetically sealed below groundwater level. With the help of dendrochronology, the scientists were able to determine the exact felling years of the trees and thus also the approximate time at which the wells were constructed.

The tests revealed that the wood comes from massive old oak trees felled by early Neolithic farmers with stone adzes between the years of 5206 and 5098 BC. The farmers cleaved the trunks into boards, assembling them to make chest-like well linings with complex corner joints. Using state-of-the-art laser scanning technology, the scientists collected data on the timbers and tool marks and documented the highly developed woodworking skills of the early Neolithic settlers. The very well-preserved tool marks and timber joints testify to unexpectedly sophisticated timber construction techniques.

In the course of the sixth millennium BC, the nomadic hunting and gathering lifestyle gave way to a sedentary lifestyle with agriculture and stock breeding in Central Europe. This break in the history of humankind has been termed the "Neolithic Revolution." A sedentary lifestyle required permanent housing, and houses are inconceivable without a developed woodworking technology -- in other words, the first farmers were also the first carpenters. Until now, however, archaeologists have only succeeded in unearthing the soil marks left by their houses.

The precisely dated wells will enable scientists to conduct more detailed studies on the important role of timber construction techniques for humankind's adoption of a sedentary lifestyle.

Allí mismo los neandertales debieron colocar una niña muerta, de dos años y medio o tres, en el suelo del refugio; encima pusieron dos lascas de piedra y un asta de uro y prendieron fuego. Baquedano explica que han encontrado unos dientes de aquella criatura, que ellos llaman la niña, aunque no tienen datos científicos para determinar el sexo, detalles sobre el asta y un trozo de carbón que ha aparecido hace solo unos días y que les facilitará una datación exacta. “Los enterramientos completos, con una estructura clara que permita reconstruir comportamientos, son muy raros en el mundo”, comenta el catedrático Arsuaga, codirector de las excavaciones de Atapuerca.

Junto a él, Baquedano muestra el punto donde han encontrado el carbón de aquella hoguera, tal vez ritual, que se podrá datar por la técnica del carbono 14. “Tenemos la convicción de que es una deposición intencionada del cuerpo de la niña; tal vez en los yacimientos de neandertales había más enterramientos y no se han reconocido como tales”, sugiere el director del museo. Lo cierto es que los neandertales cuidaban de alguna manera de sus muertos. Se han encontrado rastros en Francia e Israel.

En el valle madrileño, arqueólogos y paleontólogos se afanan a medida que pasan los días. Un total de 70 personas en tres yacimientos escarban los sedimentos con punzones y pinceles; se abren camino en la roca con taladradoras; lavan kilos y kilos de tierra extraída para que no se escape ni una minúscula pieza interesante... y se documenta cada centímetro excavado. Llevan ya una década haciendo este trabajo científico cada verano, “durante 40 días en dos turnos”, explica César Laplana, del museo regional.
Los nueve dientes de neandertal ya descubiertos tienen entre 60.000 y 90.000 años y varios han aparecido en lo que debieron ser madrigueras de hienas, que devorarían y triturarían los cuerpos. “Los dientes son el tejido orgánico más resistente, se conservan mejor que el resto del esqueleto y dan mucha información: dieta, enfermedades, paso o de niño a adulto...”, continúa Laplana.
“Los neandertales vivieron tanto en el periodo interglacial como en el glacial”, explica Arsuaga. Tras un periodo de glaciación en que media Europa sería como Groenlandia hoy, empezó, hace unos 130.000 años, el período interglacial, con un clima que llegó a ser más cálido que el actual, hasta hace 85.000 años, cuando comenzó la última glaciación, que terminó hace 11.500 años. En las excavaciones de Pinilla correspondientes al interglacial aparecen muchos restos de gamos, un cérvido muy mediterráneo; tortugas; puercoespines y osos pardos, en lugar de osos cavernarios, como en la época glacial.

En la cueva Des-Cubierta, Javier Somoza, estudiante de la Universidad de Salamanca, se acerca a Baquedano y le enseña una pieza envuelta en un papel blanco: es una herramienta que acaba de extraer. “Sí, me he emocionado mucho”, dice Somoza. Es una pieza de cuarzo rosado.

Se han encontrado ya miles de herramientas de piedra. “La mejor piedra para tallas es el sílex, pero en esta zona no hay. Así que tuvieron que apañarse. Adaptaron su técnica de talla —musteriense— a lo que tenían, que es cuarzo. Es peor, pero sirve y significa toda una adaptación tecnológica admirable”. ¿Y para cazar? “Lanzas de madera con punta endurecida al fuego”. “Aquí, en este valle de yacimientos tan ricos, podemos averiguar muchas cosas sobre los neandertales, su vida y su muerte, su medio, su clima, su tecnología, su economía... Solo es cuestión de tiempo”, concluye el arqueólogo...
Mañana en la tercera y ultima parte se de su alimentación.