̽��ֱ�� of Cambridge - Daniel Field

Bird brain from the age of dinosaurs reveals roots of avian intelligence

sc604 — Wed, 13 Nov 2024 14:20:58 +0000

A ‘one of a kind’ fossil discovery could transform our understanding of how the unique brains and intelligence of modern birds evolved, one of the most enduring mysteries of vertebrate evolution.

̽��ֱ��largest penguin that ever lived

sc604 — Thu, 09 Feb 2023 08:21:23 +0000

Fossil bones from two newly-described penguin species, one of them thought to be the largest penguin to ever live – weighing more than 150 kilograms, more than three times the size of the largest living penguins – have been unearthed in New Zealand.

Bird beak evolved before dinosaur extinction

sc604 — Wed, 30 Nov 2022 15:18:58 +0000

Fossilised fragments of a skeleton, hidden within a rock the size of a grapefruit, have helped upend one of the longest-standing assumptions about the origins of modern birds.

Tree-dwelling mammals survived after asteroid strike destroyed forests

cmm201 — Thu, 14 Oct 2021 12:10:32 +0000

Overall, the study supports the hypothesis that the widespread destruction of forests following the asteroid’s impact favoured ground-dwelling mammals over their arboreal counterparts. However, it also provides strong evidence that some tree-dwelling animals also survived the cataclysm, possibly nesting in branches through the Cretaceous-Paleogene (K-Pg) extinction event.

“ ̽��ֱ��recovery of terrestrial vertebrate life following the end-Cretaceous asteroid impact was one of the most important events in the history of life on Earth,” said senior author Dr Daniel Field, from Cambridge’s Department of Earth Sciences. “In this study, we drew on our previous work at Cambridge to investigate whether there were similarities in the ecological attributes of avian and mammalian survivors of the end-Cretaceous mass extinction.”

̽��ֱ��K-Pg mass extinction event occurred when a meteor slammed into Earth at the end of the Cretaceous period. ̽��ֱ��impact and its aftereffects killed roughly 75% of the animal and plant species on the planet, including whole groups like the non-avian dinosaurs.

For the study, the researchers analysed patterns of substrate preferences among all modern mammals and their ancestors, working backwards from the present day to before the K-Pg extinction event by tracing these traits along numerous phylogenetic trees — diagrams that illustrate the evolutionary relationships among species.

“Our study takes advantage of an ongoing revolution in our understanding of the tree of life, only made possible by researchers working in association with natural history collections,” said co-lead author Jacob Berv, from the ̽��ֱ�� of Michigan, USA. “By integrating data from such collections with modern statistical techniques, we can address new questions about major transitions in evolutionary history.”

̽��ֱ��researchers classified each mammalian species as arboreal, non-arboreal, or semi-arboreal. To be considered arboreal, the species had to nearly always nest in trees. Categorising some species could be tricky. For example, many bat species spend a lot of time among trees but nest in caves, so bats were mostly categorised as non-arboreal or semi-arboreal.

“We were able to see that leading up to the K-Pg event, there was a spike in transitions from arboreal and semi-arboreal to non-arboreal habitat use across our models,” said co-lead author Jonathan Hughes, from Cornell ̽��ֱ��, USA.

̽��ֱ��work builds on a previous study led by Field, which used the same analytical method — known as ancestral state reconstruction — to show that all modern birds evolved from ground-dwelling ancestors after the asteroid strike.

“ ̽��ֱ��fossil record of many vertebrate groups is sparse in the immediate aftermath of the extinction,” said Field, who is also curator of ornithology at the Cambridge Museum of Zoology. “Analytical approaches like ancestral state reconstruction allow us to establish hypotheses for how groups like birds and mammals made it through this cataclysm, which palaeontologists can then test when additional fossils are found.”

̽��ֱ��analysis helps illuminate ecological selectivity of mammals across the K-Pg boundary despite the relatively sparse fossil record of mammalian skeletal elements from the periods immediately preceding and following the asteroid’s impact.

How the tree-dwelling ancestors of primates survived the asteroid’s destruction is unclear. According to the authors, it’s possible that some forest fragments survived the calamity or that early primates and their relatives were ecologically flexible enough to modify their substrate preferences in a world mostly denuded of trees.

Reference:
Jonathan J Hughes et al. ‘Ecological selectivity and the evolution of mammalian substrate preference across the K–Pg boundary.’ Ecology and Evolution (2021). DOI: 10.1002/ece3.8114

Adapted from a Yale news release.

An asteroid strike 66 million years ago wiped out the non-avian dinosaurs and devastated the Earth’s forests, but tree-dwelling ancestors of primates may have survived it, according to a new study published in the journal Ecology and Evolution.

̽��ֱ��recovery of terrestrial vertebrate life following the end-Cretaceous asteroid impact was one of the most important events in the history of life on Earth

Daniel Field

Rod Waddington

Chimpanzee, Uganda

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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‘Wonderchicken’ fossil from the age of dinosaurs reveals origin of modern birds

sc604 — Wed, 18 Mar 2020 15:19:43 +0000

̽��ֱ��oldest fossil of a modern bird yet found, dating from the age of dinosaurs, has been identified by an international team of palaeontologists.

Past climate change pushed birds from the northern hemisphere to the tropics

sc604 — Mon, 10 Jun 2019 19:00:00 +0000

̽��ֱ��researchers, from the Universities of Cambridge and Oxford, applied climate and ecological modelling to illustrate how the distribution of major bird groups is linked to climate change over millions of years. However, while past climate change often occurred slowly enough to allow species to adapt or shift habitats, current rates of climate change may be too fast for many species, putting them at risk of extinction. ̽��ֱ��results are reported in Proceedings of the National Academy of Sciences.

“Palaeontologists have documented long-term links between climate and the geographic distributions of major bird groups, but the computer models needed to quantify this link had not been applied to this question until now,” said Dr Daniel Field from Cambridge’s Department of Earth Sciences, the paper’s co-lead author.

For the current study, the researchers looked at ten bird groups currently limited to the tropics, predominantly in areas that were once part of the ancient supercontinent of Gondwana (Africa, South America and Australasia). However, early fossil representatives of each of these groups have been found on northern continents, well outside their current ranges.

For example, one such group, the turacos (‘banana eaters’) are fruit-eating birds which are only found in the forests and savannahs of sub-Saharan Africa, but fossils of an early turaco relative have been found in modern-day Wyoming, in the northern United States.

Today, Wyoming is much too cold for turacos for most of the year, but during the early Palaeogene period, which began with the extinction of non-avian dinosaurs 66 million years ago, the Earth was much warmer. Over time, global climates have cooled considerably, and the ancestors of modern turacos gradually shifted their range to more suitable areas.

“We modelled the habitable area for each group of birds and found that their estimated habitable ranges in the past were very different from their geographic distributions today, in all cases shifting towards the equator over geological time,” said Dr Erin Saupe from the ̽��ֱ�� of Oxford, the paper’s other lead author.

Saupe, Field and their collaborators mapped information such as average temperature and rainfall and linked it to where each of the bird groups is found today. They used this climatic information to build an ‘ecological niche model’ to map suitable and unsuitable regions for each bird group. They then projected these ecological niche models onto palaeoclimate reconstructions to map potentially-suitable habitats over millions of years.

̽��ֱ��researchers were able to predict the geographic occurrences of fossil representatives of these groups at different points in Earth’s history. These fossils provide direct evidence that these groups were formerly distributed in very different parts of the world to where they are presently found.

“We’ve illustrated the extent to which suitable climate has dictated where these groups of animals were in the past, and where they are now,” said Field. “Depending on the predictions of climate change forecasts, this approach may also allow us to estimate where they might end up in the future.”

“Many of these groups don’t contain a large number of living species, but each lineage represents millions of years of unique evolutionary history,” said Saupe. “In the past, climate change happened slowly enough that groups were able to track suitable habitats as these moved around the globe, but now that climate change is occurring at a much faster rate, it could lead to entire branches of the tree of life going extinct in the near future.”

̽��ֱ��research was funded in part by the Natural Environment Research Council (NERC).

Reference:
Erin Saupe et al. ‘Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic.’ PNAS (2019). DOI: 10.1073/pnas.1903866116

A bold response to the world’s greatest challenge
̽��ֱ�� ̽��ֱ�� of Cambridge is building on its existing research and launching an ambitious new environment and climate change initiative. Cambridge Zero is not just about developing greener technologies. It will harness the full power of the ̽��ֱ��’s research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

Researchers have shown how millions of years of climate change affected the range and habitat of modern birds, suggesting that many groups of tropical birds may be relatively recent arrivals in their equatorial homes.

Climate has dictated where these groups of animals were in the past, and where they are now

Daniel Field

Daniel J. Field

L-R: Knysna Turaco, Great Blue Turaco, Knysna Turaco

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