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Inicio > Actualidad, Biología evolutiva > Hallan en China el antepasado más antiguo de las aves

Hallan en China el antepasado más antiguo de las aves

Esta es una de esas noticias que hay que saborear. Primero por lo que supone, retrasar el origen de las aves unos cuantos millones de años, y segundo porque está demasiado calentita para digerirla del todo. Hay que dejarla reposar para que siente bien, y ese reposo implica que hay que estudiar bien el fósil aquí presentado.

En el último número de la revista Nature, en un trabajo que firman Hu et al (2009) A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus se describe que en el yacimiento de Tiaojishan (en la provincia China de Liaoning) se ha encontrado un nuevo fósil de transición en el proceso de evolución entre los dinosaurios y las aves. El esqueleto de este animal es 10 millones de años más antiguo que los restos del ave más antigua conocida, el Archaeopteryx, encontrado en Alemania a finales del s.XIX.

Bautizado como Anchiornis huxleyi, en honor al biólogo evolutivo Thomas Henry Huxley, tiene el honor de ser la criatura emplumada más antigua de la que se tiene noticia. Los investigadores de la Universidad de Pekín, responsables del hallazgo publicado en la revista Nature, ya habían encontrado un esqueleto incompleto a principios de año, pero recientemente han podido hallar un segundo ejemplar en excelentes condiciones de conservación.

Este antepasado de las aves vivió hace 155 millones de años, en el jurásico tardío. Mide unos cincuenta centímetros, tiene cuatro alas y posee un extenso plumaje cubriendo sus brazos, cola y pies. Llama mucho la atención la presencia de 4 alas, y en un aspecto que en cierta medida me hace gracia. En algunos debates con creacionistas éstos decían, ¿cómo es que no encontramos aves con 4 alas?. Me ahorro la respuesta 😀

Según explican sus descubridores, la evolución temprana de los terópodos (como el Anchiornis) era muy poco conocida a causa de los pobres registros fósiles de finales del jurásico. Ahora afirman que el hallazgo del Anchiornis Huxleyi supone una evidencia más de que los dinosaurios son ancestros de las aves.

Entradas relacionadas:

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Hallan en China el antepasado más antiguo de las aves

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Esta es una de esas noticias que hay que saborear. Primero por lo que supone, retrasar el origen de las aves unos cuantos millones de años, y segundo porque está demasiado calentita para digerirla del todo. Hay que dejarla reposar para que siente bien, y ese reposo implica que hay que estudiar bien el fósil...

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Un fósil de 125 millones de años hallado en España ha demostrado que algunas aves ancestrales evolucionaban sobre las cabezas de los dinosaurios de un modo similar a los pájaros modernos.

Las aves tienen una historia evolutiva enormemente larga. La primera de ellas, el famoso Archaeopteryx, vivió hace 150 millones de años en lo que hoy es el sur de Alemania. Sin embargo, si estos primeros pájaros eran capaces de volar - y si es así, cómo de bien - ha permanecido en la controversia científica.

El nuevo estudio, publicado en la revista Scientific Reports, documenta la intrincada disposición de los músculos y ligamentos que controlaban las principales plumas del ala de un pájaro ancestral.

Un equipo internacional de paleontólogos españoles y el director del Insituto del Dinosuario del Natural History Museum de Los Angeles, Luis M. Chiappe, estudió el ala excepcionalmente conservado de un pájaro de 125 millones de años de edad, procedente del centro de España. Más allá de los huesos conservados en el fósil, l a pequeña ala revela detalles una compleja red de músculos que en las aves modernas controla el ajuste fino de las principales plumas del ala, permitiendo que las aves dominen el cielo.

"La relación entre la red muscular conservada en el fósil y las características de las alas de las aves actuales indica fuertemente que algunos de los primeros pájaros eran capaces de proezas aerodinámicas como muchas aves actuales", dijo Chiappe, científico principal de la investigación.

"Es muy sorprendente que a pesar de ser un esqueleto muy diferente de sus contrapartes modernas, estas aves primitivas muestran sorprendentes similitudes en su anatomía blanda", dijo Guillermo Navalón, un candidato de doctorado en la Universidad de Bristol, en el Reino Unido, y autor principal del estudio.

Los pájaros antiguos pueden haber volado sobre las cabezas de los dinosaurios, pero algunos aspectos de los modos de vuelo precisos de estos primeros pájaros todavía siguen sin estar claros. " El nuevo fósil nos proporciona una visión única de la anatomía del ala de las aves que vivieron entre algunos de los dinosaurios más grandes", dijo Chiappe. "Los fósiles como éste están permitiendo a los científicos diseccionar los aspectos más complejos de la evolución temprana del vuelo de las aves."

Otros miembros del equipo de investigación incluyen a Jesús Marugán-Lobón, José Luis Sanz, y Ángela D. Buscalioni por la Universidad Autónoma de Madrid.

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Fundaciondinosaurioscyl Salas de los Infantes

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Las aves que compartieron espacio y tiempo con los dinosaurios

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Un fósil de 125 millones de años hallado en España ha demostrado que algunas aves ancestrales evolucionaban sobre las cabezas de los dinosaurios de un modo similar a los pájaros modernos. Las aves tienen una historia evolutiva enormemente larga.

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Origen y evolución de las aves (página 2) - Monografias.com

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Origen de las aves. Pero, ¿cómo llegaron a evolucionar tanto los reptiles? La característica más importante de estos animales, es sin duda, tener las extremidades anteriores modificadas, para...

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El dinosaurio de esta semana si es conocido, no a nivel mundial como el T. rex por ejemplo, pero sí bastante conocido debido a que es uno de los dinosaurios con plumas más importante. Pero si quieren saber más datos sobre sus plumas y su historia, tamaño, descripción, etc... pueden continuar leyendo, así que adelante:

Caudipteryx sp., C. zoui y C. dongi por MattMart.

Caudipteryx fue un dinosaurio saurisquio terópodo tetanuro celurosaurio tiranorraptor maniraptor oviraptorosaurio caudiptérido. Al igual que la mayoría de los manirraptores, Caudipteryx presenta un cruce entre un pájaro y un reptil. El cráneo era corto, ancho, con forma cúbica y amplias órbitas; terminaba en un pico córneo y fuerte, además de unos pocos dientes en la mandíbula superior. Las patas anteriores acababan en unas manos con dedos con garras afiladas. En cambio, las patas posteriores eran largas y fuertes, lo que dice que fue un corredor veloz de locomoción bípeda, aunque usó su velocidad de unos 40 kilómetros por hora más o menos

Reconstrucción del esqueleto de Caudipteryx por Scott Hartman en la que se ven notablemente las piernas largas, cola corta y brazos cortos.

mayoritariamente para escapar de depredadores que para atrapar presas. Tenía una cola bastante corta que terminaba en un abanico. Esta cola tan corta afectó probablemente a la posición del cuerpo por lo que el fémur probablemente se orientó horizontalmente y no en vertical, lo que le proporcionó unos "andares" similares a los del avestruz. Se le considera un animal de dieta omnívora: el pico lo usaba para capturar a su presa y los dientes que se situaban detrás de este pico lo mataban definitivamente al agarrar a la presa. Mientras tanto, usaba los gastrolitos (como muestran los fósiles) para moler la

Caudipteryx zoui por unlobogris y Green-Mamba.

comida dentro del estómago porque el pico no estaba adaptado para masticar la comida. Esto nos deja con una dieta a partir de lagartos, pequeñas aves y mamíferos, insectos y fruta principalmente. Tenía características muy parecidas a las de los pájaros modernos, aunque unas pocas eran bastante primitivos: en resumen fue un terópodo bastante avanzado. Tenía el cuerpo completamente emplumado, unas alas que no le permitían volar y también una cola con plumas largas que formaban un abanico.

Reconstrucciones de las dos especies de Caudipteryx por Kana-hebi.

Pudo llegar a medir hasta un metro de longitud y pesaron aproximadamente siete kilogramos aproximadamente, como un pavo real, ya que tenía huesos huecos y frágiles que aligeraban el peso. Caudipteryx significa "cola emplumada". Existen dos especies: C. zoui y C. dongi. Vivió en el Barremiense, hace 125 millones de años, en el Cretáceo.

Imagen de en.wikipedia.org.

Los primeros restos fósiles de Caudipteryx se encontraron en Liaoning, en China, en el año 1997 y el género fue nombrado por Philip Currie, Ji Qiang, Mark Norell y Ji Shuan. Hasta el momento, se han descubierto exactamente dos especies: una en 1998 (C. zoui) y la otra en el año 2000 (C. dongi). Algunos paleontólogos piensan que este dinosaurio fue la prueba definitiva para terminar con la duda de la descendencia de los pájaros a partir de los dinosaurios. Hay algunos paleontólogos que incluso piensan que Caudipteryx no es en verdad un dinosaurio no aviano terópodo y cree que fue un pájaro que no volaba, al igual que las avestruces o emúes.

Caudipteryx de commons.wikimedia.org.

LAS PLUMAS
En los brazos se encontraban plumas simétricas, con barbas y raquis y con una longitud de entre 15 y 20 centímetros que formaban algo parecido a alas, aunque no le servían para volar, debido a su longitud y también a su simetría y su posición paralela al resto del cuerpo. Las plumas fueron usadas probablemente para desplegarlas para asustar a los depredadores y atrapar a la pareja, por lo que fueron usadas para cortejar. Éstas eran plumas primarias y en los fósiles de Caudipteryx no se han presenciado restos de plumas secundarias. También tenía una especie de abanico en la cola con plumas de 20 centímetros que partían desde los huesos menos largos de su cola y ayudaban a estabilizarse mientras corría. También se han encontrado plumas pennáceas parecidas a las de las aves de hoy en día.

Imagen de es.wiki2.org en la que se ven notablemente todas plumas del dinosaurio.

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El dinosaurio de esta semana si es conocido, no a nivel mundial como el T. rex por ejemplo, pero sí bastante conocido debido a que es uno de los dinosaurios con plumas más importante. Pero si quieren saber más datos sobre sus plumas y su historia, tamaño, descripción, etc...

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The oldest record of ornithuromorpha from the early cretaceous of China. 2015. Wang, M., et. al. Nature Communications

Abstract: Ornithuromorpha is the most inclusive clade containing extant birds but not the Mesozoic Enantiornithes. The early evolutionary history of this avian clade has been advanced with recent discoveries from Cretaceous deposits, indicating that Ornithuromorpha and Enantiornithes are the two major avian groups in Mesozoic.

Here we report on a new ornithuromorph bird, Archaeornithura meemannae gen. et sp. nov., from the second oldest avian-bearing deposits (130.7 Ma) in the world. The new taxon is referable to the Hongshanornithidae and constitutes the oldest record of the Ornithuromorpha.

However, A. meemannae shows few primitive features relative to younger hongshanornithids and is deeply nested within the Hongshanornithidae, suggesting that this clade is already well established. The new discovery extends the record of Ornithuromorpha by five to six million years, which in turn pushes back the divergence times of early avian lingeages into the Early Cretaceous.

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Archaeornithura , A New Early Cretaceous Ornithuromorph Bird

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The oldest record of ornithuromorpha from the early cretaceous of China. 2015. Wang, M., et. al. Nature Communications Abstract: Ornithuromorpha is the most inclusive clade containing extant birds but not the Mesozoic Enantiornithes. The early evolutionary history of this avian clade has been advanced with recent discoveries from Cretaceous deposits, indicating that Ornithuromorpha and Enantiornithes are the two major avian groups in Mesozoic.

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National Geographic 246,123 views Dinosaurs & Middle Earth

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St Clair County Community College STEM Conference Keynote Presentation

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Hunting Dinosaurs with Dr. Robert Bakker

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In this video, hunt dinosaurs with famed paleontologist and HMNS curator of paleontology Dr. Robert Bakker. The video was shot in May 2008 on the ranch in Montana where Leonardo, the mummified dinosaur on display in Dinosaur Mummy CSI: Cretaceous Science Investigation through Jan. 11, 2009, was found.

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Dinosaurs and the Call of Paleontology (Robert Bakker)

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Step backward in time to visit the age of the dinosaurs with acclaimed American paleontologist Robert Bakker. Bakker shares his fascination for the Jurassic age with Upon Reflection host Al Page and dispels some of the myths and uncertainty surrounding conventional portrayals of dinosaurs.

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Robert Bakker is an unusual academic and scholar, and as a result does not fit well into the mold of the other academics and scholars listed among the prominent Dutch Americans. However, his ground breaking work in the field of dinosaur paleontology and his efforts at publicizing his theories clearly earn him a spot among the other prominent academics and scholars listed.

In 1986, Bakker published his ground breaking work entitled, "Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and their Extinction". In this book he argues that dinosaurs were not slow-moving, slow-witted, cold-blooded creatures as represented by the then accepted paleontologic and scientific community. Instead he argued that they were, at least in some cases, warm-blooded giants that were well equipped to roam and dominate our planet for 200 million years. He also argued in the book that dinosaurs are the ancestors of birds, a theory that is now apparently not as hotly questioned as it was when the book first came out.

Bakker was born in Bergen, New Jersey, on March 24, 1945. When he was a young boy his parents took him to the American Museum of Natural History in New York City, and Bakker saw his first exhibit of dinosaurs. He was fascinated by them and even then vowed that he wanted to become a paleontologist. When he was eight years old, in 1953, he saw a copy of a Life Magazine in his grandfather's house. The magazine cover displayed part of Rudolph Zallinger's famous 1947 mural, "The Age of Reptiles", at Yale University's Peabody Museum. The article inside the magazine hooked Bakker for life. Interestingly, 15 years later, in 1968, he graduated from the University, Yale, where the mural was displayed in the Peabody museum. At Yale, Bakker studied under John Ostrom, an early proponent of the new theory about dinosaurs. And that exposure only fuelled Bakker's interest in dinosaurs still further. It was at Yale that Ostrom and Bakker first raised the theory that dinosaurs were not cold-blooded brutes, but at least some were warm-blooded, highly adaptable, highly intelligent, and highly social creatures.

Following his undergraduate studies at Yale, Bakker went on to Harvard for graduate work, where he studied Anatomy and Zoology. He received his Ph.D. Degree in 1971, and following his graduation accepted an appointment at Johns Hopkins University as a Lecturer of Anatomy. He continued his research in dinosaurs while at Johns Hopkins, and also continued working with John Ostrom. The two researchers are credited with initiating the ongoing dinosaur renaissance in paleontological studies. Bakker published an article in Scientific American, in April 1975, entitled, "Dinosaur Renaissance". At that time his special field was the ecological context and behavior of dinosaurs.

Bakker published his first paper on dinosaur endothermy, about warm-bloodedness of dinosaurs, in 1968. He also was able to determine parental care at nesting sites for Allosaurus, a type of dinosaur. His on-site research has been done in Wyoming, especially at Como Bluff, Wyoming, where he has done field work every summer since 1974. However, he has traveled as far as South Africa and Mongolia in pursuit of dinosaur habitats.

In his efforts to publicize his work to the general public and to raise public interest in dinosaurs he has been involved in non-scientific areas and publications. He wrote and had a novel published entitled, "Raptor Red". The novel tells of a year in the life of a female Utahraptor, a member of the lower Cretaceous. The book elaborates on Bakker's theories of the behavior and life of dromaeosaurids which are raptor dinosaurs. Also the bearded paleontologist, Dr. Robert Burke, in Steven Spielberg's film, "The Lost World: Jurassic Park", is an affectionate caricature of Bakker. The character is eventually eaten by a Tyrannosaurus.

Bakker currently is involved in a number of paleontology-related activities. He is an Adjunct Curator at the Tate Museum at Casper College in Casper, Wyoming. He is also the Director of the Morrison Natural Museum in Morrison, Colorado. Furthermore, he recently was appointed a Visiting Curator of Paleontology at the Houston, Texas Museum of Natural Science. In addition he frequently consults on paleontology-related issues for museums and other organizations,

Not much is known about Bakker's family or private life. Apparently he has been married four times. He also is a Pentecostal preacher and believes that one should be open-minded on the issues of evolution and creationism. He lives in Wyoming and Colorado, and is active in leading fossil digs, focusing of course, on dinosaur bones in the State of Wyoming.
REFERENCES
Legends of Paleontology: Robert Bakker, www.prehistoricplanet.com/features/paleontologists/bakker.htm

Robert T. Bakker, www.nndb.com/people/871/000092595

Robert T. Bakker, http://en.wikipedia.org/wiki/Robert_T._Bakker

Robert Bakker-Paleontologist-Interview, www.findarticles.com/p/articles/mi_m1430/is_ n6_v14/ai_11910718
E-BOOKS AVAILABLE FROM AMAZON; GOOGLE: Kindle Store Pegels PROMINENT DUTCH AMERICANS, CURRENT AND HISTORIC
EIGHT PROMINENT DUTCH AMERICAN FAMILIES: THE ROOSEVELTS, VANDERBILTS AND OTHERS, 2015

FIFTEEN PROMINENT DUTCH AMERICAN FAMILIES: THE VAN BURENS, KOCH BROTHERS, VOORHEES AND OTHERS, 2015

PROMINENT DUTCH AMERICANS IN U.S. GOVERNMENT LEADERSHIP POSITIONS, 2015
DUTCH PEGELS INVOLVED IN WARS
ALLIED EUROPE CAMPAIGN-1944/1945: TACTICAL MISTAKES, 2017

THE SECOND WORLD WAR IN THE NETHERLANDS: MEMOIRS, 2017

FRENCH REVOLUTION, NAPOLEON AND RUSSIAN WAR OF 1812, 2015

About the New Netherland Institute

For a quarter century NNI has helped cast light on America's Dutch roots. In 2010, it partnered with the New York State Office of Cultural Education to establish the New Netherland Research Center, with matching funds from the State of the Netherlands. NNI is registered as a 501(c)(3) non-profit organization. Contributions are tax-deductible to the extent permitted by law.

The New Netherland Research Center

Housed in the New York State Library, the NNRC offers students, educators, scholars and researchers a vast collection of early documents and reference works on America's Dutch era. Directed by Dr. Charles Gehring. More

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Robert Bakker is an unusual academic and scholar, and as a result does not fit well into the mold of the other academics and scholars listed among the prominent Dutch Americans. However, his ground breaking work in the field of dinosaur paleontology and his efforts at publicizing his theories clearly earn him a spot among the other prominent academics and scholars listed.

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Robert Bakker

Robert T. Bakker (born March 24, 1945) is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor John Ostrom, Bakker was responsible for initiating the ongoing "dinosaur renaissance" in paleontological studies, beginning with Bakker's article " dinosaur renaissance" in Scientific American, April 1975. Bakker has been a major proponent of the theory that dinosaurs were "warm-blooded", smart, fast, and adaptable. Bakker was among the advisers for the film Jurassic Park. Bakker currently serves at the Houston Museum of Natural Science as the Curator of Paleontology.

In the novel Jurassic Park it is said that Dr. Bakker and Alan Grant were the key persons in the "Dinosaur Renaissance", the view that dinosaurs were warm-blooded, intelligent, fast, and adaptable.

Jurassic Park Edit

Dr. Bakker is briefly mentioned in Jurassic Park by Tim:

So like I was saying, there's this other book by a guy named Bakker? And he said dinosaurs died of a bunch of diseases? He definitely didn't say they turned into birds. Bakker has indeed argued that dinosaurs died out as a result of diseases. But he definitely endorses the theory that dinosaurs evolved into birds, he was the one who proposed to put the dinosaurs and birds into one clade.

The Lost World: Jurassic Park Edit

The bearded paleontologist Dr. Robert Burke from The Lost World: Jurassic Park is an affectionate caricature of Bakker, who is eaten by a Tyrannosaurus rex in the film when he hides behind a waterfall. According to Jack Horner, part of the waterfall scene was written in as a favor for him by Spielberg. Burke greatly resembles Horners' rival, Robert Bakker. In real life, Bakker argues for a predatory T. rex. Horner, meanwhile, views it as primarily a scavenger. So Spielberg wrote Burke into this part to have him killed by the Tyrannosaurus rex as a favor for Horner. After the film came out Bakker, who recognized himself in Burke and loved it, actually sent Horner a message saying, "See, I told you T. rex was a hunter!".

Sega Genesis Jurrasic Park Commercial

Robert T. Bakker appears in the commercial of the Jurassic Park SEGA Game.

Additionally, he appears in the Sega CD Jurassic Park game on information kiosks to explain facts about the different dinosaurs the player encounters.

In the Jurassic Park: Redemption series the paleontologist Dr. Backer is a caricature of Robert Bakker.

Robert Bakker played a major role in the documentary film The Real Jurassic Park. The film scene in which Tim says "there's this other book by a guy named Bakker" is used to introduce him.

He explains the way to create dinosaurs by contra-evolve modern birds.

1. ↑ Jurassic Park script, page 48.

2. ↑ Bakker, R. T., Galton, P., 1974. Dinosaur monophyly and a new class of vertebrates. Nature 248:168-172.

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Robert T. Bakker (born March 24, 1945) is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor John Ostrom, Bakker was responsible for initiating the ongoing "dinosaur renaissance" in paleontological studies, beginning with Bakker's article "dinosaur renaissance" in Scientific American, April 1975.

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PRIMERA PARTE

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Dinosaur! The Tale of a Feather (Part 1)

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An episode of a 4 part series hosted by Walter Cronkite. This episodes focuses mainly on the extinction of the dinosaurs and their relationship to modern day birds.

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In the summer of 1970, early in the research that would radically transform how we think about birds, dinosaurs, and the origins of animal flight, Yale paleontologist John H. Ostrom was traveling through Europe studying pterosaur fossils. His itinerary took him, in early September, to the Teylers Museum in Haarlem, the Netherlands. Ostrom, then 42, was an unprepossessing figure and the world's leading authority on dinosaurs, and the museum curator was pleased to leave him alone with the twin halves of the limestone slab catalogued TM6928 and 29.

This fossil was a dinner plate-size muddle of limb fragments, vertebrae, and ribs preserved in limestone from the Solnhofen beds. It had been discovered near Riedenburg, Germany, in 1855 and named by the great nineteenth-century paleontologist Hermann von Meyer. Von Meyer later became famous for the first scientific description, in 1861, of Archaeopteryx. Coming just after the publication of Charles Darwin's On the Origin of Species, the unveiling of that 150-million-year-old urvogel, or archetypal primitive bird, made an international sensation. With Archaeopteryx, it seemed as if the proof of evolutionary theory had arrived, like the Ten Commandments, engraved in stone. But in 1857, the confusing fossil von Meyer was describing-the future TM6928 and 29-seemed like something far more ordinary: another pterosaur, a type of flying reptile. He dubbed it Pterodactylus crassipes.

That didn't make sense to Ostrom as he puzzled over the ankles, toes, and arm bones of the fossil that day in 1970. He could envision the ways they might fit together just by examining the proportions of the bones and the shape of their articulations. But it wasn't like any pterosaur he had ever seen. Ostrom had recently finished describing a remarkable dinosaur he had discovered a few years earlier in Montana. His monograph on Deinonychus included exquisitely detailed descriptions showing how the bone endings and attachments helped make these dinosaurs such fast, agile little killers. To Ostrom, the bones of the Teylers specimen looked an awful lot like those of Deinonychus. And there was something more.

Ostrom picked up one of the slabs, carried it over to the window, and held it up at an angle in the light. First one way, then the other. The late afternoon sun caught on some faint ridges. Ostrom was seeing, unmistakably, the clear impression of feathers. This fossil wasn't Pterodactylus after all. It was another Archaeopteryx. In fact, it would have been the scientific world's first Archaeopteryx, if von Meyer had gotten his taxonomy right.

In 1970, only three other specimens of Archaeopteryx were known to exist. But this was by no means the only thing that excited Ostrom at that moment. His mind was already ticking over about the resemblance to Deinonychus -and the unsettling idea that the wrist and shoulder bones of a primitive bird should be identical to those of a small meat-eating dinosaur.

To write a proper technical description, Ostrom needed to take the specimen home to the Peabody Museum at Yale for closer study. A crisis of conscience ensued: should he mislead the Teylers curator, telling him it was merely a pterosaur, only to make the great discovery back home? Or should he come out with the truth and risk that the museum would lock up these suddenly precious slabs of rock? Being a "squeaking honest" man, in the words of a former student, Ostrom confessed his belief that it was Archaeopteryx.

The curator immediately took back TM6928 and 29 and hurried out of the room. Ostrom slumped in his seat, despairing. A few minutes later, the curator returned with a shoebox tied up with string. He handed it to Ostrom, with the specimen inside, and, beaming, declared, "You have made our museum famous." It was the beginning of something far bigger than either man could have guessed.

In the public imagination then, dinosaurs were plodding, thunderous monsters, cold-blooded and stupid. Even paleontologists had lost interest in these "symbols of obsolescence and hulking inefficiency," Ostrom's student Robert T. Bakker '67 later wrote. "They did not appear to merit much serious study because they did not seem to go anywhere: no modern vertebrate groups were descended from them."

But dinosaurs had begun to look a lot more interesting one afternoon in late August, 1964, near Bridger, Montana. Ostrom and his assistant Grant E. Meyer had been walking a landscape of prairie punctuated with rocky, eroding outcrops, considering sites for the following summer's fieldwork, when they spotted a large, clawed dinosaur hand protruding from the earth on a slope just below them.

They scrambled down, dropped to their knees beside it, and because they hadn't brought their toolkit, began digging excitedly with their hands, and then with their jackknives, turning up a scattering of the serrated teeth of a predator. Next day, returning with proper tools, they unearthed an astonishing foot. Two of three toes had ordinary claws. But from the innermost toe, a sharp sickle-shaped claw curved murderously up and out. It had a slashing arc, Ostrom later calculated, of 180 degrees. Hence the eventual name Deinonychus, or "terrible claw."

Ostrom and his crew spent two full field seasons digging at the site and three years in study and reconstruction at the Peabody, working with more than a thousand bones from at least four individuals of the same species. Then in 1969, Ostrom announced what he called a "grandiose" conclusion: that foot was "perhaps the most revealing bit of anatomical evidence" in decades about how dinosaurs really behaved. In place of the plodding, cold-blooded dinosaur stereotype, Deinonychus "must have been a fleet-footed, highly predaceous, extremely agile, and very active animal, sensitive to many stimuli and quick in its responses," Ostrom wrote.

The "dinosaur renaissance," as Robert Bakker later dubbed it, had begun.

Bakker had been a student member of the 1964 Montana expedition, and he contributed a drawing to Ostrom's paper showing a fleshed-out Deinonychus in full sprint. The "terrible claw" on the hind legs was lifted up and out of the way of its feet, keeping it sharp. That drawing would soon become the icon of the new dinosaur.

Bakker had latched onto many of Ostrom's ideas as an undergraduate and, to Ostrom's occasional chagrin, he ran with them. Bakker-"the infamous Bob Bakker," as Peter Dodson '74PhD, another former Ostrom student, says-became the outspoken advocate of dinosaurs as active, warm-blooded, and even "superior" animals. "Where John was cautious, Bob was evangelical," Dodson and Philip Gingerich '74PhD later wrote. "Each deserves considerable credit for revolutionizing our concept of dinosaurs."

In his book The Riddle of the Dinosaur, science writer John Noble Wilford added that Bakker "was the young Turk whose views could be dismissed by established paleontologists. Ostrom, however, could not be ignored." Late in 1969, Ostrom took the challenge directly to the North American Paleontological Convention in Chicago, declaring in a speech that there was "impressive, if not compelling" evidence "that many different kinds of ancient reptiles were characterized by mammalian or avian levels of metabolism." Traditionalists in the audience responded, Bakker later recalled, with "shrieks of horror." Their dusty museum pieces were threatening to come to life as real animals.

Ostrom went on, over the next half dozen years, to draw out the similarities between Deinonychus and Archaeopteryx specimens, including the Teylers fossil. Among the titles in a series of landmark papers he published: "The Ancestry of Birds," "The Origin of Birds," and " Archaeopteryx and the Origin of Flight." The idea that birds had evolved from dinosaurs was not entirely new, as Ostrom pointed out. T. H. Huxley, "Darwin's Bulldog," had argued, for instance, that a link between the reptile-like bird Archaeopteryx and the bird-like reptile Compsognathus would close an evolutionary gap. But subsequent scientific opinion had shifted to the counter-argument-that the many similarities between birds and dinosaurs were merely instances of convergent or parallel evolution. Paleontologist Gerhard Heilmann's 1926 book The Origin of Birds killed off the dinosaur connection seemingly forever. His argument came down to wishbones: Birds had what is properly known as a furcula. Dinosaurs didn't even seem to have the collarbones, or clavicles, that fuse to form the furcula.

Ostrom pointed out that this was "negative evidence only and thus inconclusive." A lot of biological features are missing from the fossil record, he noted, and that doesn't make them any less real. Collarbones in particular are delicate and might easily not have survived, or not in any recognizable form. In any case, several dinosaurs with clavicles had already turned up before Heilmann published his book. Many more have come to light since then. Against this false negative, Ostrom laid out the positive evidence, listing more than 20 anatomical similarities between Archaeopteryx and various dinosaurs. It wasn't just that Ostrom could not be ignored. He was far too thorough and meticulous, and for 30 years too persistent in the face of his critics, for anyone to refute.

Though one or two holdouts still resist the idea, it is now widely accepted that birds evolved from the group of bipedal theropod dinosaurs that includes Deinonychus, Tyrannosaurus, Velociraptor, and other familiar species. They are now all grouped together as Maniraptora, or "hand-snatchers," a taxonomic classification named in 1986 by Jacques Gauthier (now a Peabody curator). The idea that birds are in fact living dinosaurs is so commonplace that the debate has largely turned to the question of why they were the only dinosaurs to survive the mass extinction of 65 million years ago.

Ostrom gave up fieldwork in the 1970s because of a physical ailment. But he had always believed that "the best discoveries are made in museum storerooms," and his own correct identification of TM6928 and 29 had been "a classic example of why a paleontologist or museum should not throw things away that can't be absolutely classified as worthless." Holed up in his paper-stacked office at the Peabody, studying fossils with his magnifying spectacles, he continued to publish important articles on dinosaurs, birds, and the evolution of avian flight.

As Ostrom quietly continued his work, the dinosaur renaissance spread out from that office to become a "dinosaurian flooding of popular consciousness," as the paleontologist Stephen Jay Gould later put it-with countless books, endless computer-generated dinosaurs on television, and multiple iterations of Jurassic Park, the last of these directly inspired by Ostrom and Deinonychus. The dinosaur renaissance also caused a debate that persists even now, among bemused paleontologists and parents alike, about why so many of our children are caught up in the raging, teeth-baring grip of full-on dinomania. (The short answer: John Ostrom.)

More significantly, Ostrom lived to see his ideas about the dinosaur origin of birds-and the feathered plumage of dinosaurs-vindicated by a series of remarkable fossils from northeastern China. These discoveries began in 1996, with Sinosauropteryx ("Chinese lizard wing"), a small theropod dinosaur with a mantle of short, dark, feather-like filaments on its back. ("I literally got weak in the knees when I first saw photos," Ostrom told a reporter.) And it culminated in 2012 with the 3,100-pound Yutyrannus, a T. rex relative, only bigger, fiercer, and covered in tufts of long, filamentous feathers. Canadian researchers browsing through a museum collection of amber even found actual dinosaur feathers and downy "dino fuzz."

The Jurassic Park movie franchise (with the fourth installment now in production) continues to hold out for scaly, reptilian dinosaurs, to the chagrin of better-informed children in the audience. But scientific and popular renderings of many dinosaur species now look as ornately feathered as faux Indians at Mardi Gras. On Ostrom's death in 2005, age 77, the Los Angeles Times wrote that he had "almost single-handedly convinced the scientific community that birds are descended from dinosaurs." "John Ostrom," the Sunday Times (London) added, "did more than anyone else to make dinosaurs interesting, real, and visceral."

When NPR's All Things Considered marked the occasion by interviewing Ostrom's first research student, Bob Bakker, the paleontological world held its breath for a moment, recalling the troubled relationship between these two allies in the dinosaur renaissance. But when asked how important Ostrom had been to dinosaur paleontology, Bakker graciously commented: "Nobody was more important."

Eight years before his death, Ostrom himself had already published what was his own best epitaph, in the view of the Peabody's Daniel Brinkman '94MPhil. In "a last word" to a paper called "How Bird Flight Might Have Come About," Ostrom wrote: "The missing, unknowable fossil record can never be allowed to stifle our curiosity."

There is one more piece of this story that's never been told in print: heading back to his hotel with the Teylers specimen that day in 1970, having discovered the first new Archaeopteryx in 24 years, Ostrom had to stop at a public restroom. Afterward, he continued on his route, perhaps caught up in contemplating the struggle and the triumphs ahead.

Suddenly, to his horror, he realized that he was empty-handed.

He had left the shoebox containing not just the fossil, but also his destiny, the fame of the Teylers Museum, the course of paleontology for decades to come, and the not-yet-imagined dinosaur dreams of untold armies of dinosaur enthusiasts, perched, abandoned, on a wash basin in a public restroom. Ostrom frantically retraced his footsteps-and found the shoebox untouched. He snatched it up and clutched it to his breast all the way back to the hotel, and to New Haven. And thus John H. Ostrom saved the future for dinosaurs.

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In the summer of 1970, early in the research that would radically transform how we think about birds, dinosaurs, and the origins of animal flight, Yale paleontologist John H. Ostrom was traveling through Europe studying pterosaur fossils. His itinerary took him, in early September, to the Teylers Museum in Haarlem, the Netherlands.