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Pterosaur Feathers Deepen Debate Over Their Evolution

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pterosaur feathers

Artist rendering of a short-tailed pterosaur feathers and all. (Credit: Yuan Zhang/Nature Ecology & Evolution)

The discovery of novel filaments on two species of pterosaur suggests that the extinct flying reptiles had complex coats of “feathers” and fuzz, say the authors of a new study. The presence of these apparent pterosaur feathers may indicate that the ancestor of both pterosaurs and their cousins, dinosaurs, sported similar coverings — but that’s not the only hypothesis.

Like dinosaurs, pterosaurs are archosaurs. This group of reptiles, which also includes crocodilians, likely emerged in the Late Permian Period (more than 250 million years ago) and dominated the Mesozoic Era that followed. Archosaurs abounded, all the way up until about 66 million years ago and the end-Cretaceous mass extinction, which spared only one dinosaur lineage (birds) and some crocodilians.

True feathers, with complex, branched structures, have been found on several theropods — one of the main branches of the dinosaur family tree and the lineage that includes birds. Less complex filaments, akin to fuzz or down, have been found on a few non-theropod dinosaurs.

For decades, paleontologists have also found filaments on well-preserved pterosaur fossils. These filaments, known as pycnofibers, have been simple structures — think a hollow, unbranched tube — that illustrators typically render as a fur-like covering when recreating the animals.

A More Complex Story Takes Shape

Today, however, researchers announce that they have found four different types of pycnofibers on two specimens of short-tailed pterosaurs from the Middle-Late Jurassic of China, more than 160 million years ago.

Type 1, as described in the new study, is the simple, hollow pycnofiber seen on other pterosaur fossils. This type covers most of the body of each specimen, reminiscent of mammalian underfur, say the authors, suggesting it may have played a role in thermoregulation.

The other three types, however, appear to be branched structures and are present only in specific areas. Type 4, for example, which superficially resembles a tree branch (see (n) in image below), occurs only on the wing membranes.

Fossilized filamentous structures. Credit: Baoyu Jiang, Michael Benton et al./Nature Ecology & Evolution

Fossilized pterosaur pycnofibers found on the individuals include Type 1, a simple hollow tube (e) and three more complex types that the authors say have branching structures similar to true feathers (h, k, n). (Credit: Baoyu Jiang, Michael Benton et al./Nature Ecology & Evolution)

Types 2 and 3 (h and k, above) appear to have different branching structures and were found only on small areas of the head, neck and limbs of one specimen.

Further analysis of all four types of pycnofibers revealed they have a chemical signature similar to that of human hair and the feathers of living birds.

Preserved within the pycnofibers, say the authors, are melanosomes: cellular structures that provide clues to the animal’s pigmentation in life. Fossilized melanosomes recently have been used to reconstruct iridescent dinosaur feathers, but the pterosaurs were apparently not quite so flamboyant. Based on their melanosomes, the flying reptiles would have been mostly brown.

Convergent Controversy

The presence of apparently branched pycnofibers on the fossils reinvigorates a general debate over feathers in Archosauria. Researchers and armchair paleontologists alike have long argued over when true feathers evolved and in which lineages.

(Most scientists believe the first feathers probably emerged for insulation and display, such as to signal an individual’s fitness to a potential mate. Only much later along the evolutionary road were they co-opted, by some species, for use in flight.)

One school of thought holds that true, branched feathers evolved among theropod dinosaurs, though not every theropod sported them. There is no evidence, for example, that T. rex and other iconic megapredators had feathers. This hypothesis suggests that any unbranched feathers or other filamentous structures found on pterosaurs and non-theropod dinosaurs were examples of convergent evolution, when unrelated species occupying the same ecological niche evolve similar traits.

According to this hypothesis, pterosaurs’ pycnofibers arose independently from dinosaur feathers.

The new analysis of the two Chinese pterosaurs’ pycnofibers, however, could be seen as evidence for another hypothesis: that the currently unknown archosaur ancestor of both dinosaurs and pterosaurs had feathers of some type, and passed the trait down to both groups.

Phylogenetic comparative analysis of integumentary filament and feather evolution in pterosaurs and archosaurs. Credit: Baoyu Jiang, Michael Benton et al./Nature Ecology & Evolution

The authors of today’s research included a comparative analysis of filament and feather evolution in pterosaurs and other archosaurs, notably dinosaurs. (Credit: Baoyu Jiang, Michael Benton et al./Nature Ecology & Evolution)

Today’s paper is not the first time researchers have declared they’ve essentially found pterosaur feathers. Pycnofibers on another Chinese pterosaur, Pterorhynchus wellnhoferi, were described as branching and homologous to feathers, though subsequent analysis by other paleontologists questioned those conclusions. That earlier paper, like today’s study, is no slam-dunk in part because analysis of the pycnofibers is as much art as science, and open to interpretation.

The new research appears in Nature Ecology & Evolution.

 

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Ecology

Yukon and Northern BC First Nations tackle climate change using Indigenous knowledge and science

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YUKON, June 18, 2021 /CNW/ – The Government of Canada is working together in partnership with Indigenous and Northern communities in finding solutions to adapt to the impacts of climate change in the North.

Today, Minister of Northern Affairs, Daniel Vandal, along with Parliamentary Secretary to the Minister of Economic Development and Official Languages (Canadian Northern Economic Development Agency), Larry Bagnell, highlighted progress on three unique, Indigenous-led projects that are helping communities in Yukon and Northern British Columbia adapt to the challenges posed by climate change.

The Minister and Parliamentary Secretary met virtually with Carcross/Tagish First Nation (C/TFN) to learn about their community-led climate change monitoring program. C/TFN has partnered with Tsay Keh Dene Nation (TKDN) and Chu Cho Environmental of Prince George, British Columbia, to build a community-led monitoring project that examines environmental data and Indigenous knowledge to create a holistic picture of how the climate is changing across C/TFN and TKDN traditional territories. The project combines tracking of current and historical climate trends with knowledge shared by Elders while also providing opportunities for youth mentorship and climate change awareness.

The Taku River Tlingit First Nation (TRTFN) is also leading a unique project to assess the impacts of climate change within their traditional territory. Climate change is causing many of the culturally significant ice patches to melt, exposing organic artifacts to oxygen and leading to rapid deterioration. The TRTFN ice patch mapping project will involve performing archaeological assessments to prevent the degradation of artifacts. Research will be guided by traditional knowledge, Elders and oral histories, when available, and heavily involve community, Elders, youth and Knowledge Keepers.

The Pelly Crossing Selkirk Development Corporation is leading the Selkirk Wind Resource Assessment project through the installation of a Sonic Detection and Ranging (SODAR) system. The initiative includes a feasibility study leading up to the construction of a renewable energy facility, including wind, solar and battery energy storage. Expanding clean energy within the region will have direct benefits for communities, including reduced reliance on diesel, job creation and revenue generation for Selkirk First Nation. 

These projects are delivering important environmental, social and economic benefits that lead to healthier, more sustainable and resilient communities across Yukon and Northern British Columbia. They also build community clean energy capacity and help to avoid the impacts of climate change.

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Ecology

Atlantic Provinces Ready For Aquaculture Growth

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Aquaculture is an important economic driver for rural, coastal and Indigenous communities, and Atlantic Canada is well positioned to increase aquaculture production as global demand for sustainably sourced seafood grows.

That is why the ministers responsible for aquaculture in the Atlantic provinces have agreed to the ongoing development and management of their industries based on common principles. A new memorandum of understanding has been signed by the four ministers, which extends the previous agreement signed in 2008.

“In a time when food security is especially important, it is good to see our aquaculture industry has grown steadily and is poised for continued growth in 2021 based on environmentally responsible, science-based policies and practices,” said Keith Colwell, Minister of Fisheries and Aquaculture for Nova Scotia. “Our Atlantic partnership continues to help the industry grow sustainably.”

Cooperation between the provinces and the aquaculture industry has led to improvements in pest management, environmentally sustainable aquaculture methods, aquatic animal health and policies to support the shared use of marine and freshwater resources. It also aims to align regulation and policy between the provinces to make the regulatory requirements easier to understand by industry and the public.

Each province has a comprehensive and robust legislative and regulatory framework to ensure environmental sustainability, economic prosperity and public accountability. The provinces update their legislation and regulations regularly. Nova Scotia revamped its regulatory framework in 2015; New Brunswick received Royal Assent for a new Aquaculture Act in 2019 and is working on the supporting regulations; Newfoundland and Labrador completely revised its aquaculture policy in 2019; and Prince Edward Island has recently drafted a new Aquaculture Act.

The ministers have agreed to continue to use science-based evidence for management decisions, thereby increasing public and investor confidence in the Atlantic Canadian aquaculture industry.

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Ecology

COMING SOON: A Healthy Environment and a Healthy Economy 2.0

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We all want the same thing: a clean and responsible energy future for our children and future generations while continuing to enjoy a high standard of living.

On December 11, 2020, the Prime Minister announced a new climate plan which he claimed will help achieve Canada’s economic and environmental goals.

The proposed plan by Environment and Climate Change Canada (ECCC) entitled “A Healthy Environment and a Healthy Economy” will have an initial investment of $15 billion of taxpayer’s money. It is built on 5 pillars of action:

  1) Making the Places Canadians Live and Gather More Affordable by Cutting Energy Waste

2) Making Clean, Affordable Transportation and Power Available in Every Community

3) Continuing to Ensure Pollution isn’t Free and Households Get More Money Back

4) Building Canada’s Clean Industrial Advantage

5) Embracing the Power of Nature to Support Healthier Families and More Resilient Communities  

In my paper, “A Healthy Environment and a Healthy Economy 2.0” I will objectively critique each pillar in the government’s new climate plan and provide alternative solutions to the same issues.

  This is an alternative plan that supports workers, protects lower income earners and creates economic growth while respecting the environment and focusing on the dignity of work.

  This plan abandons virtue-signaling projects and relies on Canadian ingenuity to build our economy and restore Canada’s role of responsible leadership in the world.

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