Farewell to the voyager

After 33 years of traveling and unconditionally helping us to understand our universe, Voyager 1 is no longer in our neighborhood. The spacecraft is now at the almost incomprehensible distance of more than 17 billion (17 x 10⁹) km from its home planet -our beloved Earth- and has left the influence from our Sun. In other words, the Voyager 1 has finally left our Solar System.

Artist concept of the two Voyager spacecraft as they approach interstellar space. Image credit: NASA/JPL.

The spacecraft is now in a region called "heliosheath", were the solar wind of our Sun has a velocity of almost zero in relation to our star.

Voyager 1 was launched by NASA on September 5th, 1977, while its twin, the Voyager-2, was launched some days earlier, on August 20th. Together, they have studied all the exterior planets of our Solar System (Jupiter, Saturn, Uranus and Neptune -no, I'm not forgetting Pluto: it's no longer a planet, get over it!).

 Artist rendering of the Voyager 1.

Voyager 1 is since February 17, 1998 the man-made object most distant from Earth, after it surpassed the distances traveled by the spacecrafts Pioneer 10 and 11.

More information on the Voyager 1 status and in the mission in general can be found here and here, respectively.

2012 phenomenon is a hoax

Ok, just a short one. The title of this post explains itself:

www.2012hoax.org

And some Neil Degrasse Tyson, of course.

Kitten vs Dinosaur

Originally from the Cat versus Human blog.

Sunlight our future

So, we all know that using crude oil for feeding our civilization has several environmental, social and economical cons. Looking for a viable, clean and cheap source of energy is an imperative. Solar energy has been seen for a long time as promising replacement for petroleum, but, how feasable is to use it?

Parabolic dishes in Almeria, Spain, used to obtain solar energy. Photo by the Sandia National Laboratory.

Well, solar power is still vigorous, at least according to iSuppli, a market research firm. Thru a press release, iSuppli states that the market for this kind of energy is expected to grow more than 40% in 2011 compared to this year. However, solar energy market has shrunk compared to 2009, when it grew almost 98% compared to the precedent year.

Graphic by iSuppli

Recently, the South African government anounced that they are building the biggest solar energy plant ever constructed. As well, Europe will have its biggest solar energy plant in Italy.

A new (?) eurogiant

From the almost prehistoric times when there was no Internet, I am back with some news about our old good fellows, the dinosaurs. This time we go again to Spain, exactly to Teruel, where a team of paleontologists has discovered the fossil of the largest dinosaur's femur (the upper bone of the leg) ever to be found in Europe.

 Location of Teruel, Spain

Along with the femur, which measures 1,92 m, there have been found a right tibia 1,25 m long, 15 tail vertebrae, 11 chevrons, a nearly complete set of teeth and part of the skull. The sediments surrounding the bones are 145 million years old, so this dinosaur may have lived in between the late Jurassic and the early Cretaceous.

 

Photo by Dinopolis, the Teruel dinosaur thematic park.

In 2006, Turiasaurus riodevensis (something like "lizard of Riodeva, Turia", being Turia the latin name for Teruel), the biggest European dinosaur known until now (with a lenght exceeding 30 m), was unearthed from this same spot (the Riodeva dig). However, the discovery can't be yet assigned to a species, neither T. riodevensis nor a new one.

Reconstruction of Turiosaurus riovedensis, by Carin L. Cain.

The flamboyant, brand-new Triceratops's cousins

Two new species of Ceratopsians (group of horned, plant-eating dinosaurs whose most famous representative is the Triceratops) have been discovered in Utah, U.S.A. The bigger of them has been named Utahceratops ("Horned face from Utah") and  is interesting mainly because of  its almost horizontal brow horns, a completely new feature within Ceratopsians. The other one is simply too baroque: it has 15 horns! Kosmoceratops (something like "Ornamented horned face"), has the most decorated head of all Dinosaurs discovered so far.

Artist's reconstructions of the heads of Kosmoceratops (left) and Utahceratops (right), by Lukas Panzarin.

Comparison between the Utahceratops (left) and Kosmoceratops (right) skeletons, by Scott D. Sampson et al. The bones colored in yellow are the ones that were recovered.

Once believed to be used as a defense against carnivores, the horns and all other features that were characteristic of Ceratopsids skulls are now thought to be mainly ornamental. Each species had a very particular set of horns and neck frills that may be used to spot representatives of their own kind, as well as to show off and engage in battle between males during the mating season, the same way as most Cervids do nowadays.

Like Ceratopsians? This is the second post of this blog related to this group of Dinosaurs. Click here to see the first one.

30 seconds on Mars

Brief news on the red planet and related stuff:

• Last week, NASA's Mars Reconnaisance Orbiter (MRO) spoted rocks from a Martian area called Nili Fossae that may contain fosilized life, as they are very similar to Stromatolites, rocky formations from Pilbara, Australia, that were created by the activity of some of the earliest life forms on Earth.
• This week, the MRO rebooted and put itself in safe mode for an unknown reason, but it's back online.
• Meanwhile, Italian astrophysicists stated during the European Congress of Planetary Science that Phobos (one of the two Martian moons, being the other one Deimos) may have been originated from an asteroid impact with Mars and that is not a meteorite captured by the red planet, as it was previously thought.

Mars.

Shrunk and gone: a story about the Moon

Have you ever seen the Moon low in the horizon, when it is just rising? Do you remember how big it looks at that moment and how it seems to have shrunk when it is high in the sky? Well, even if this phenomenon is caused by an optical illuson, our natural satellite is actually shrinking.

 Photograph by Justo Ruiz.

The Lunar Reconnaisance Orbiter (LRO), an artificial satellite launched on June18th, 2009 by the US's National Aeronautics and Space Administration (NASA) to study the Moon discovered what have been called lobated scarfs, a type of cliffs caused by the Moon's shrinkage.

The data obtained by the LRO shows that the Moon has reduced its radius in 100 m during a yet indetermined time span -it may go from one hundred thousand (1 x 10⁵) to one billion (1 x 10⁹) years. Yet, the Moon's shrinkage, caused by the cooling of its is interior, is not affecting its crust as it is already cold, thus causing this one to wrinkle. This is, roughly, how the lobated scarfes are originated.

Graphic showing how lobated scarfs are created, as the Moon's crust is pushed together due to our natural satellite's shrinkage. Image by NASA.

So, the Moon is shrinking, but is still ours, as always, right? Well, not forever, because the Moon is actually moving away from us and will eventually be gone forever.

The gravitational interaction between the Earth and the Moon that is responsible for the tidals of our seas is causing our natural satellite to be 3,8 cm farther away from us and is accelerating its revolution time around our planet to compensate this fact.

So, the Moon will look smaller and smaller each year in the sky and someday, in a very distant future, it won't be there no more. Don't believe me? Just watch:

Now, here's the explanation on why this is happening:

More information on the shrinking Moon can be found here.

So far yet so close (at least roughly)

By the end of August 2010, the biggest extrasolar planetary system discovered so far was announced by a team of European astronomers from the European Southern Observatory (ESO).

Artist recreation of the recently discovered extrasolar planetary system. Original image from ESO.

Five planets have been confirmed to orbit HD 10180, a star very similar to our Sun located 127 million light-years from us, within the Hydrus constellation. There is also the possibilty that two more planets orbit the star and, if that's the case, the HD 10180 system will be almost as big as ours, given that our cosmic neighborhood consists of eight planets (Pluto is no longer one, remember?).

Yet, seemingly so close to our solar system, there are major differences to take into account. The five confirmed planets are as big as Neptune and their orbits span from six to 600 Earth days.

One of the unconfirmed planets may be the size of Saturn and would orbit HD 10180 in 2200 Earth days. The other one may be 1,4 times the size of our planet, but it's yet quite far from habitable (at least by us) as it would be so close to its star that its "year" lasts only 1,18 Earth days. Besides that, this "evil twin" of the Earth is the smallest planet discoverd so far.

The discovery of this rich extrasolar planetary system took about six years and was performed using the world's most powerful spectrograph, an instrument that captures and analyzes light signatures, at ESO's telescope at La Silla, Chile.

The first extrasolar planet was discovered in 1995 around 51 Pegasi and was called 51 Pegasi b, being abbreviated as 51 Peg b and nicknamed Bellerophon. As of September 8th, 2010, there have been announced 490 confirmed detections of such celestial bodies.

More information on the HD 10180 system can be found here. As well, an official video from ESO about the program can be seen below.

One hundred days of solitude (so far)

Now we jump from the prehistoric times to a not so far future, a time when the first manned mission to Mars is deployed. When is this going to happen? So far, nothing's for sure, but, if we trust Barack Obama, it's going to happen by the third decade of this century.

But now, here on Earth, specifically in Moscow, Russia, a experiment is already being held regarding the effects on humans that the long journey from our planet to Mars may cause. Six male volunteers from Russia (3), Italy (1), France (1) and China (2) have been living isolatedly for about one hundred days in an facility designed ad hoc for testing the psychological demands of an interplanetarian trip.

The Mars500 crew. Photo from ESA's Mars500 program page.

Leaded by Commander Alexei Sitev, a Russian engineer, the team will leave the facility they have been living in since June 3rd, 2010 by the day 520 of isolation, i.e., on November 5th, 2011. Until that date, the men will have to share a space consisting in four hermetically sealed interconnected sections, consisting in habitable, medical and storage modules, as well as a Mars Landing simulator. They even have gym and sauna.

The first 250 days of isolation will consist in the "trip to Mars", followed by 30 days for "orbiting and landing on Mars", while the final 240 days will be for "going back to Earth". The presumed distances

This experiment is being carried out by Russia's Institute for Biomedical Problems (IBMP), the Russian Academy of Sciences and the European Space Agency (ESA) and is the third phase of the Mars500 program.

The first stage, developed during November 2007, consisted in a 15-days isolation for equipment, facilities and operating procedures testing and involved a different group of six volunteers (one of them being a woman). The second phase of the Mars500 program, developed with an all-Russian team, consisted in a trip simulation similar to the one being currently held, but designed to last only 105 days. It was completed on June 3rd, 2010.

More information on the Mars500 program can be found here.

The hunchback of Cuenca

 

Reconstruction of the possible aspect of C. corcovatus, by Raul Martin. Alternative recreations here and here, thanks to Alain Bénéteau.

Unearthed from Las Hoyas deposit (Cuenca, Spain), the fossil of this theropod surprised its discoverers at first due to the bone prolongation of the front vertebrae of its pelvis, responsible for its notorious hump. This feature led this new species to be baptized as Concavenator corcovatus ("hunchback hunter of Cuenca").

However, the importance of this fossil, nicknamed "Pepito" by the paleontologist that brought it to light, goes beyond the peculiarity described lines above. In fact, its arms have small bumps that are very similar to those present in the Coelurosaurids and their living descendants, the Birds, that hold the large wing feathers used by the latter for powered flight.

The fascinating (and exciting) thing about this feature is that "Pepito" belongs to a group of dinosaurs (the

Allosaurids) which representatives, until now, did not presented any evidence of having feathers or similar structures. The discovery of this Spanish reptile may indicate that feathers would have appeared far before of what was considered this far, i.e., in the more primitive dinosaurs that were common ancesters for Coelurosaurids as well as for the group that contains C. corcovatus.

Underlined in red in the graphic bellow (based on a cladogram proposed by Weishampel et al. in 2004) are the dinosaur groups whit at least one feathered representative:

As can be seen, the Alosaurids may ben counted from now on within the feathered dinosaurs thanks to the discovery of the Concavenator.

The find of "Pepito" seems to underpin the idea that feathers were a feature common to all dinosaur groups, along with evidence from species with no relation with theropods such as the Psittacosaurus and the Tianyulong, which may have had (at least) proto-feathers.

Yes, I know: and what about the hump? Well, about it, two hypothesis have been formulated so far:

1. That it may have been (as usual) an exhibitional structure to attract females.
2. That it may worked as a thermal regulator element, likewise the Spinosaurus sail, animal main character of the latest movie of the Jurassic Park saga.

Some final data on C. corcovatus:

• The Cuenca fossil is the most complete dinosaur scheleton discovered in Spain so far. Even fossilized skin was discovered.
• It lived between 130 and 125 million years ago approximately, during the Early Cretaceous.
• It was about four meters long.

More information on "Pepito" can be found here.

Dinosaurs and Heavy Metal!

What else can I ask for? I give you Hevisaurus, Finnish band of "Dino-Metal". No wonder Newsweek declared Finland as the best country of the world.

This post may be anything but scientific, but simply this blog could not leave pass by a marvel like this. One single example may prove my point: the music video of Jee Hevisaurus, second track of the album Jurahevin Kuninkaat ("Kings of Jurassic Heavy" in Finnish).

For those of you who can't access the video for the nonsense of a company that took down the YouTube profile of its artist for uploading her own music videos, you can watch it here.

More information on the band here and here.

JEE HEVISAURUS!

The bad guy in the neighborhood would not come alone

Indeed, before coming, he may have sent his minions to play havoc. I am talking about the asteroid that is believed to have impacetd the Earth about 65 million years ago and that is thought to have caused the Cretaceous-Tertiary extinction event.


The discovery of a crater in Ukraine and its date would strengthen the theory that the end of the reign of dinosaurs was not caused by a single impact of an asteroid with our planet, but by a meteor shower that would have lasted several thousand years.

The Boltysh crater (Kirovohrad, Ukraine) was discovered in the 60s during an oil exploration. However, its correct dating could only be done until recently through the study of fossil spores, establishing that the asteroid that caused it would have impacted between 2 and 5 thousand years before the most famous meteorite responsible for the Chicxulub crater (Yucatan, Mexico).

The date of the impact, established by a team of investigators of the Aberdeen University leaded by the Geology Doctor David Jolley, was published through an article of the Geology magazine in August 2010. The study states that it is highly probable that between the impacts of Boltysh and Chicxilub may have been several similar collisions, being a millenary meteor shower the responsible for the massive extinction event of the end of the Cretacic and not a single happening.

The meteor that fell onto the Cretaceous Ukraine may have eradicated much of the biodiversity that at that time populated Eastern Europe and Russia. Similar events over thousands of years would have done the same in different parts of the globe, until the end of the Mesozoic party was declared by the arrival of the Yucatan asteroid.
You may find more information here.

Finally, I leave you with a very illustrative video (with a very sardonic ending if you ask me) abaout the possible consequences of an asteroid impact with our planet.

Original image by Lee Krystek, slightly adapted by your humble servant.

Great-great-grandfathersuchids and great-great-grandsonsaurids

Bellow, the most recent genealogical tree of the dinosaurs (until 2008), elaborated by the Bristol University. It includes 99,2% of the species discovered so far:

Yes, I know, is as big as a Baobab. Here you can find a larger article on this marvel.

Tri-toro-cera-top-saurus?

Ok. This is the story that inspired me to start this blog:

"Study discovers that Triceratops and Torosaurus were different stages of the same dinosaur"

It turns out that John Scanella, postgraduate student of the Montana State University (MSU), and Jack Horner, paleontologist very well recognized in the scientific scene, have published a study that states that Triceratops, one of the most famous dinosaurs of the world (maybe as much as its contemporary, the Tyrannosaurus rex) was nothing but a juvenile form of the animal known until now as Torosaurus, a reptile quite more anonymous in the popular imaginary.











Proposal of Scanella and Horner about the juvenile (izq.) and adult (right) appearences of the Triceratops face, formerly assigned to adult specimens of Triceratops and Torosaurus, respectively. Original image available at Physorg.com


Getting aknowledge about this story, published in the July 14th edition of the Journal of Vertebrate Paleontology magazine of the The Society of Vertebrate Paleontology, made me feel something like when I first saw the "Star Wars: The Empire Strikes Back" scene in which Luke Skywalker discovers that Darth Vader is his father.Well, maybe I'm exagerating, but I was truly astonished and felt my interest in science journalism renewed.

Back to topic, the most immediate consequence of this study is that the genus "Torosaurus" will disappear from the scientific texts and the name "Triceratops" will prevail, as this term was coined first and, in situations like this, the first in line is the only one to stay (as has happened before with the denomination "Brontosaurus").

However, this discovery has more profound implications. If the affirmation of Scanella and Horner is true, it will become one more proof to support the theory that the biodiversity of the dinosaurs was, by the end of the Cretaceous, less more than was thought some years ago.

In other words, the dinosaurs may have been already on their way to extinction by the time the asteroid that created the Chicxulub crater impacted the Eartch about 65 million years ago. This celestial clash is considered as one of the most possible causes of the Cretaceous-Tertiary extinction event, which meant the end of the Mesozoic Era (popularly known as the Age of Reptiles or the Age of Dinosaurs) and the beginning of the Cenozoic Era, also called the Age of Mammals, within which we still live.

El jorobado de Cuenca

 

Reproducción del posible aspecto del C. corcovatus a cargo de Raúl Martín. Recreaciones alternativas aquí y aquí, gracias a Alain Bénéteau.

Desenterrado del yacimiento de Las Hoyas (Cuenca, España), el fósil de este dinosaurio terópodo sorprendió en principio a sus descubridores debido a las prolongaciones oseas de las vértebras anteriores de su pelvis, responsables de su notoria joroba. Esta característica le valió el que fuera bautizado como Concavenator corcovatus ("cazador jorobado de Cuenca").

Sin embargo, la importancia de este fósil, apodado "Pepito" por los paleontólogos que lo trajeron a la luz, va más allá de la peculiaridad mencionada líneas arriba. En efecto, sus brazos presentan rebordes óseos muy similares a los que poseen los Coelurosaurios y sus descendientes actuales, las Aves, y en los cuales se afianzan las grandes plumas de las alas que sirven para el vuelo sostenido de estas últimas.

Lo inquietante (y emocionante) de esta característica es que "Pepito" pertenece a un grupo de dinosaurios (los Alosáuridos) cuyos representantes, hasta ahora, no presentaban evidencia alguna de poseer plumas o estructuras similares. El descubrimiento de este reptil español parece indicar que las plumas habrían aparecido mucho antes de lo que se consideraba hasta el momento, esto es, en los dinosaurios primitivos que fueron antepasados comunes tanto de los Coelurosáuridos como del grupo que contiene al C. corcovatus.

Subrayados en rojo en el cuadro siguiente (basado en el cladograma propuesto por Weishampel et al. en 2004), pueden apreciarse los grupos de dinosaurios con al menos un representante emplumado:

Como se aprecia, los Alosáuridos se contarían a partir de ahora entre los dinosaurios con plumas gracias al descubrimiento del Concavenator.

El hallazgo de "Pepito" también parece apuntalar la idea de que las plumas fueran una característica extendida entre todos los dinosaurios, junto a evidencias aportadas por especies no emparentadas con los terópodos como el Psittacosaurus y el Tianyulong, los cuales podrían haber tenido (al menos) protoplumas.

Sí, lo sé: ¿y qué hay de la joroba? Bueno, pues al respecto se han formulado, por el momento, dos hipótesis:

1. Que sería (para variar) una estructura de exhibición para atraer a las hembras.
2. Que serviría como un elemento regulador de la temperatura, como la vela del Spinosaurus, protagonista animal de la última entrega de la saga Jurassic Park.

Algunos datos finales sobre el C. corcovatus:

• El fósil de Cuenca constituye el esqueleto de dinosaurio más completo descubierto en España a la fecha. Incluso se descubrieron restos de piel fosilizada.
• Vivió entre 130 y 125 millones de años atrás aproximadamente, durante el Cretácico temprano.
• Midió alrededor de cuatro metros de largo.

Más información sobre "Pepito" aquí y aquí.

¡Dinosaurios y heavy metal!

¿Qué más puede pedir un servidor? Con ustedes, Hevisaurus, banda finlandesa de "dino-metal". No por nada Newsweek declaró a Finlandia como el mejor país del mundo.

Este post no tendrá nada de científico, pero simplemente en este blog no se podía pasar por alto una maravilla como ésta. Para muestra, un botón: el video de Jee Hevisaurus, segunda pista del álbum Jurahevin Kuninkaat ("Reyes del heavy jurásico").

Para aquellos que no puedan acceder al video por la insesatez de una compañía que bloqueó el perfil de YouTube de su artista por subir sus propias canciones, pueden verlo aquí.

Más información sobre la banda aquí y aquí.

JEE HEVISAURUS!

El malo del barrio no habría venido solo

Así es, antes de llegar, habría enviado a sus esbirros a hacer estragos. Estoy hablando del asteroide que se cree que impactó la Tierra hace aproximadamente 65 millones de años y que se tiene como principal causante de la extinción masiva del final del Cretácico.

El descubrimiento de un cráter en Ucrania y su datación fortalecerían la teoría de que el fin del reinado de los dinosaurios no fue causado por un solo impacto de un asteoride con nuestro planeta, sino por una lluvia de meteoritos que habría durado varios miles de años.

El cráter de Boltysh (Kirovohrad, Ucrania) fue descubierto en los años 60 durante una exploración petrolífera. Sin embargo, su correcta datación sólo pudo realizarse hasta hace poco a través del estudio de esporas fosilizadas, estableciéndose que el asteroide que lo causó habría impactado entre 2 y 5 mil años antes del más famoso meteorito causante del cráter de Chicxulub (Yucatán, México).

La fecha del impacto, establecida por un equipo de investigadores de la Universidad de Aberdeen liderado por el Doctor en Geología David Jolley, fue publicada a través de un artículo en la revista Geology en agosto de 2010. El estudio señala que es muy probable que entre los impactos de Boltysh y de Chicxilub haya habido varias colisiones similares, por lo que habría sido una lluvia meteórica milenaria la causante de la extinción masiva del final del Cretácico y no un solo suceso.

El bólido que cayó en la Ucrania cretácica habría erradicado gran parte de la biodiversidad que por aquella época poblaba Europa del Este y Rusia. Eventos similares a lo largo de miles de años habrían hecho lo propio en diferentes partes del globo, hasta que el fin de la fiesta mesozoica fue decretado con la llegada del meteorito de Yucatán.

Pueden encontrar más información al respecto aquí.

Finalmente, los dejo con un muy ilustrativo video (con un final bastante sardónico a mi parecer) sobre las posibles consecuencias del impacto de un asteroide con nuestro planeta.

Imagen original por Lee Krystek, adaptada por un servidor.

Tatarabuelitosúquidos y nietosáuridos

A continuación, el más reciente árbol genealógico de los dinosaurios (hasta 2008), elaborado por la Universidad de Bristol y que incluye al 99,2% de las especies descubiertas hasta el momento:

Sí, lo sé, es enorme como un Baobab. Pueden encontrar un artículo más extenso sobre esta preciosidad aquí (en Inglés).

¿Tri-toro-cera-top-saurus?

Ok. Ésta es la noticia que me inspiró a empezar este blog:

"Estudio descubre que el Triceratops y el Torosaurus eran diferentes etapas de un mismo dinosaurio"

Resulta que John Scanella, estudiante de posgrado de la Montana State University (MSU), y Jack Horner, paleontólogo más que reconocido en el mundo científico, han publicado un estudio en el que se afirma que el Triceratops, uno de los dinosaurios más famosos del mundo (quizás tanto como su contemporáneo, el Tyrannosaurus rex) era en realidad una forma juvenil del animal hasta ahora conocido como Torosaurus, réptil algo más anónimo en el imaginario popular.





Propuesta de Scanella y Horner sobre las apariencias juvenil (izq.) y adulta (der.) del rostro de un Triceratops, antes asignadas a ejemplares adultos de Triceratops y Torosaurus, respectiv amente. Imagen original disponible en Physorg.com

El impacto que me causó el enterarme de esta noticia, publicada en la edición del pasado 14 de julio de la revista Journal of Vertebrate Paleontoly de The Society of Vertebrate Paleontology, representa para mí algo similar a lo que sentí cuando vi por primera vez la escena de "Star Wars: The Empire Strikes Back" en que Luke Skywalker descubre que Darth Vader es su padre. Bueno, tal vez exagero, pero sí que me dejó atónito y revitalizó mi interés en la difusión científica.

Volviendo al tema, la consecuencia más inmediata de este estudio es que el género "Torosaurus" desaparecerá de los textos científicos y prevalecerá el nombre "Triceratops", pues este término fue acuñado antes y, en situaciones como ésta, el primero que llega, se queda (como ya pasó antes con la denominación "Brontosaurio").

Sin embargo, este descubrimiento tiene repercusiones mayores. De ser cierta la afirmación de Scanella y Horner, se convertiría en una prueba más de que la biodiversidad de los dinosaurios sería, hacia el fin del Cretácico, mucho menor de lo que se daba por sentada hace algunos años.

En otras palabras, los dinosaurios podrían haber ya estado en vías de extinción para cuando el meteorito que creó el cráter de Chicxulub impactó con la Tierra hace aproximadamente 65 millones de años. Este encontronazo celestial es considerada como una de las causas más probables de la extinción del Cretácico-Terciario, hecho que significó el fin de la Era Mesozoica (popularmente conocida como Era de los Reptiles o de los Dinosaurios) y que dio paso a la Era Cenozoica, también llamada Era de los mamíferos, en la que aún vivimos.