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Ancient Arctic Nursery: 73 Million-Year-Old Bird Fossils Discovered in Alaska

For half of the time birds have existed on Earth – a staggering 150 million years – they’ve been nesting in the Arctic, according to a groundbreaking paper featured in Science. The study reveals that millions of birds gathered in the polar regions 73 million years ago, raising their young amidst dinosaurs and other prehistoric creatures.

The research, led by Lauren Wilson from Princeton University, is based on dozens of tiny fossilized bones and teeth found at an Alaska excavation site. These ancient bird fossils, which include diving birds resembling loons, gull-like birds, and various types of ducks and geese, push back the record of birds breeding in the polar regions by 25 to 30 million years.

Prior to this study, the earliest known evidence of birds reproducing in either the Arctic or Antarctic was about 47 million years ago. This new discovery sheds light on the evolution of modern bird species and highlights the importance of the Arctic as a nursery for these animals.

The fossil collection is part of the University of Alaska Museum of the North’s collections, and the research team used an uncommon excavation and analysis approach to recover the tiny bones and teeth. By examining every bone and tooth they could find, from the visible to the microscopic, the scientists were able to identify multiple types of birds that coexisted with dinosaurs in the Arctic.

This study has significant implications for our understanding of bird evolution and the behavior of ancient species. As Pat Druckenmiller, senior author of the paper and director of the University of Alaska Museum of the North, notes, “The Arctic is considered the nursery for modern birds. It’s kind of cool when you go to Creamer’s Field [a Fairbanks-area stopover for migrating geese, ducks, and cranes] to know that they have been doing this for 73 million years.”

While further research is needed to confirm whether these ancient bird fossils belong to the Neornithes group (which includes all modern birds), this study has already pushed back the record of birds breeding in the polar regions by millions of years. The findings are a testament to the value of an uncommon approach to fossil hunting and highlight the importance of continued research into the evolution and behavior of ancient species.

The discovery of a nearly complete fossil of what looked like a lizard or salamander in Scotland in 1984 has turned out to be a significant find. The creature, called Westlothiana lizziae, is one of the earliest examples of a four-legged animal that had evolved from living underwater to dwelling on earth. It and other stem tetrapods like it are common ancestors of the amphibians, birds, reptiles, and mammals that exist today, including humans.

Despite its significance, researchers had never determined an accurate age of the fossil. However, thanks to new research out of The University of Texas at Austin, scientists now know that the Westlothiana lizziae, along with similar salamander-like creatures from the same spot in Scotland, are potentially 14 million years older than previously thought.

The new age – dating back to 346 million years ago – adds to the significance of the find because it places the specimens in a mysterious hole in the fossil record called Romer’s Gap. This time period, from 360 to 345 million years ago, is where water-dwelling fish took an evolutionary leap, growing lungs and four legs to become land animals.

The research, published recently in the journal PLOS One, was led by Hector Garza, who just graduated with his doctoral degree from the Department of Earth and Planetary Sciences at the UT Jackson School of Geosciences. Garza used a geochemical technique called radiometric dating to determine the age of the fossils. This technique involves using zircon crystals to date rocks, but not all rock types are amenable to this type of analysis.

The site in Scotland where the fossils were discovered was near ancient volcanoes whose lava flows had long hardened into basalt rock, where zircons do not typically form. Fellow scientists warned Garza that chemically dating the rocks might be fruitless. However, he got lucky and was able to extract zircons from the rock surrounding six of the fossils.

Garza X-rayed 11 of the rock samples at the Jackson School and conducted uranium-lead laser dating on the zircons at the University of Houston to determine their oldest possible age. Before Garza’s gamble, scientists had figured the fossils were as old as similar fossils from around the world – about 331 million years old.

The more accurate, older maximum age of 346 million years is significant because it places the specimens in Romer’s Gap. This time period is crucial to understanding the timing of the emergence of vertebrates on land and why this transition occurs when it does.

“I can’t overstate the importance of the iconic East Kirkland tetrapods,” said Julia Clarke, professor at the Jackson School and co-author of this paper. “Better constraining the age of these fossils is key to understanding the timing of the emergence of vertebrates on to land. Timing in turn is key to assessing why this transition occurs when it does and what factors in the environment may be linked to this event.”

The site in Scotland where the fossils were found, the East Kirkton Quarry, is a veritable treasure trove of early tetrapod records. Seven stem tetrapod fossils, including the Westlothiana lizziae, have been found there. Hundreds of millions of years ago when these early four-legged creatures roamed, this site was a tropical forest with nearby active volcanoes, a toxic lake, and a diverse plant and animal community.

The National Museum of Scotland provided Garza with bits of rock that surrounded the fossils to use for the sampling. Other study co-authors are Associate Professor Elizabeth Catlos and Michael Brookfield, both of the Department of Earth and Planetary Sciences at the Jackson School, and Thomas Lapen, professor and chair of the Department of Earth and Atmospheric Sciences at the University of Houston.

Revolutionizing Our Understanding of Stegosaurian Evolution: A Groundbreaking Discovery in Spain

A team of palaeontologists from the Fundación Conjunto Paleontológico de Teruel-Dinópolis has made a groundbreaking discovery in the municipality of Riodeva, Teruel, Spain. The researchers have uncovered a remarkably well-preserved stegosaurian skull, which they believe to be the most complete specimen ever found in Europe. This extraordinary find not only sheds new light on the anatomy of Dacentrurus armatus, but also challenges our current understanding of the evolutionary history of plated dinosaurs.

The stegosaur’s skull was discovered during excavations at the “Están de Colón” fossil site, which dates back to the Late Jurassic epoch, approximately 150 million years ago. This exceptional specimen has allowed the researchers to study previously unknown aspects of Dacentrurus armatus anatomy. The detailed analysis of this remarkable fossil has provided valuable insights into how stegosaurian skulls evolved.

Furthermore, alongside the anatomical study, the researchers have proposed a new hypothesis that redefines the evolutionary relationships of stegosaurs worldwide. This new group, called Neostegosauria, includes medium to large-sized stegosaurian species that lived in Africa and Europe during the Middle and Late Jurassic, North America during the Late Jurassic, and Asia during the Late Jurassic and Early Cretaceous.

“The study of this exceptional fossil has allowed us to reveal previously unknown aspects of the anatomy of Dacentrurus armatus,” explains Sergio Sánchez Fenollosa, a researcher at the Fundación Dinópolis. “Dinosaurian skulls are rarely preserved due to their extreme fragility, making this discovery key to understanding how stegosaurian skulls evolved.”

Alberto Cobos, managing director of the Fundación Dinópolis and co-author of the publication, adds: “This dual achievement-both the study of an exceptional fossil and the proposal of a new evolutionary hypothesis-positions this research as a global reference in stegosaurian studies. This fossil site from Riodeva continues to be a subject of research and still holds numerous relevant fossils, including more postcranial elements from the same adult specimen and, notably, juvenile individuals, a particularly rare combination in this type of dinosaurs.”

The discovery has not only shed new light on the evolution of stegosaurs but also exponentially increased the palaeontological heritage of the province of Teruel. As Cobos notes: “Making it one of the iconic regions for understanding the evolution of life on Earth.”