Skull of Smallest Known Dinosaur Found in 99-Million-Year Old Amber
Editor's Note from The Conversation, July 28, 2020: This article was based on a study published in the peer-reviewed journal Nature on March 11, 2020. On July 22, 2020, the journal retracted the article after other researchers raised concerns that the skull belonged to a lizard, not a bird. Here is the retraction note from the paper's authors: "We, the authors, are retracting this Article to prevent inaccurate information from remaining in the literature. Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis regarding the phylogenetic position of HPG-15-3."
In 2016, our colleague Xing Lida held up a small piece of polished, deeply yellow amber. As sunlight shone through the ancient resin, Lida saw the outline of a pristinely preserved, amazingly small skull. There was a prominent eye socket, a dome-shaped crown of the head, a long, tapering snout and even small teeth. It was bird-like, but in a strange and ancient way.
The amber contains the skull of Oculudentavis khaungraae, a newly described dinosaur and one of the smallest ever discovered. Its tiny stature is forcing paleontologists to rethink the lower limits of body size in birds, and the nearly 100-million-year-old fossil is challenging the current understanding of when and how dinosaur giants shrank into the birds of today.
A Mysterious Transformation
Tiny Oculudentavis may have occupied a unique ecological niche in the ancient world. Han Zhixin / CC BY-ND
The evolutionary transition of dinosaurs to modern birds is one of the most astounding transformations in the history of life: large, bipedal and mostly carnivorous dinosaurs morphed into small, flying birds. Famous discoveries like Archaeopteryx and more recently the fossils from the Jehol Biota in China have given researchers some hints about the process. But finds from this evolutionary phase — which researchers think began about 200 million years ago — are rare.
Paleontologists are far from having a complete picture of the evolution of birds, and even farther from a full inventory of Earth's ecosystems in the age of dinosaurs. Our research on the tiny Oculudentavis, published in the journal Nature, adds valuable information to the puzzle of when, how and to what extent dinosaurs shrank.
Clues in Bone
This high-resolution scan allowed us to see the intricacies of a bone structure unlike any before seen in birds or dinosaurs. Xing Lida / CC BY-ND
Our team needed to see the minute details of the skull, and we needed to do it without cracking or ruining the specimen - a difficult task with a skull encased in 99-million-year old amber from Myanmar. To do that, we scanned the skull with high-resolution X-rays and created a digital model with very fine anatomical detail. What emerged was a picture of an overall bird-like anatomy. But in some interesting ways, Oculudentavis is unlike any bird or dinosaur that has ever been found.
The obvious curiosity of the fossil is its size: Oculudentavis rivaled the smallest bird living today, the bee hummingbird, and likely was no more than 1.6 inches (4 centimeters) from beak to tail. We considered whether the skull possibly belonged to a very young animal, but the extent and pattern of bone growth and the proportional size of the eye pointed to a mature bird.
With a total skull length of just about 0.6 inches (1.5 centimeters), Oculudentavis pushes against what is considered the lower limit of size in birds: the head still had to hold functional eyes, a brain and jaws. The small size is especially surprising if one considers that Oculudentavis lived during the same time as giant plant-eating dinosaurs like Argentinosaurus.
Small and Specialized
The small size of Oculudentavis is striking, but to a trained eye there are other extremely unusual features, too.
First of all, the skull seems to be built for strength. The bones show an unusual pattern of fusion and the skull lacks an antorbital fenestra, a small hole often found in front of the eye.
The eyes of Oculudentavis also surprised us. The shape of the bones found within the eye, the scleral ossicles, suggests that it probably had conical eyes with small pupils. This type of eye structure is especially well adapted for moving around in bright light. While daytime activity might be expected for an ancient bird from the age of dinosaurs, the shape of the ossicles is entirely distinct from any other dinosaur and resembles those of modern-day lizards.
Adding to the list of unexpected features, the upper jaw carries at least 23 small teeth. These teeth extend all the way back beneath the eye and are not set in deep pockets, an unusual arrangement for most ancient birds. The large number of teeth and their sharp cutting edges suggest that Oculudentavis was a predator that may have fed on small bugs.
The sum of these traits — a strong skull, good eyesight and a hunter's set of teeth — suggests to us that Oculudentavis led a life previously unknown among ancient birds: it was a hummingbird-sized daytime predator.
One of the Earliest and Tiniest Birds?
Placing Oculudentavis in the tree of life is, given its strange anatomy, challenging. Our phylogenetic analysis — the investigation of its relationships to other dinosaurs — identifies Oculudentavis as one of the most ancient birds. Only Archaeopteryx branched off earlier.
Scientists consider the nectar-feeding hummingbirds — which appeared 30 million years ago — the smallest dinosaurs on record. But if our placement of Oculudentavis holds true, the miniaturization of dinosaurs may have peaked far earlier than paleontologists previously thought. In fact, the largest and the smallest dinosaurs may have walked and flown the same earth nearly 100 million years ago.
Our work demonstrates how little scientists know about the little things in the history of life. Scientists' snapshot of fossil ecosystems in the dinosaur age is incomplete and leaves so many questions unanswered. But paleontologists are eager to take on these questions. What other tiny species were out there? What was their ecological function? Was Oculudentavis the only visually guided bug hunter? To better understand the evolution of the diversity of life we need more emphasis and recognition of the small.
Amber holds strong potential to fill that gap. Maybe one day a scientist will hold up another piece, and let sunshine reveal a complete Oculudentavis, or even a previously unknown species. More finds in amber will help illuminate the world of the tiny vertebrates in the age of dinosaurs.
Reposted with permission from The Conversation.
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As we reach the official end of hurricane season, 2020 will be one for the record books. Looking back at these long, surprising, sometimes downright crazy past six months (seven if you count when the first named storms actually started forming), there are many noteworthy statistics and patterns that drive home the significance of this hurricane season, and the ways climate change may have contributed to it.
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EcoWatch Daily Newsletter
By Dana Drugmand
An unprecedented climate lawsuit brought by six Portuguese youths is to be fast-tracked at Europe's highest court, it was announced today.
The European Court of Human Rights said the case, which accuses 33 European nations of violating the applicants' right to life by disregarding the climate emergency, would be granted priority status due to the "importance and urgency of the issues raised."
‘Protect Our Future’<p>Cláudia Agostinho (21), Catarina Mota (20), Martim Agostinho (17), Sofia Oliveira (15), André Oliveira (12) and Mariana Agostinho (8) are <a href="https://www.desmogblog.com/2020/09/03/youth-climate-lawsuit-portugal-33-european-countries" target="_blank">bringing the case</a> with nonprofit law firm Global Legal Action Network (<span style="background-color: initial;">GLAN</span>), arguing that none of the countries have sufficiently ambitious targets to cut their emissions.</p><p>Portugal recently sweltered through its <a href="https://www.ipma.pt/pt/media/noticias/news.detail.jsp?f=/pt/media/noticias/textos/resumo-clima-julho-20.html" target="_blank">hottest July in 90 years</a> and has seen a rise in devastating heatwaves and wildfires over recent years due to rising temperatures. Four of the applicants live in Leiria, one of the regions worst-hit by the forest fires that killed more than 120 people in 2017. </p><p>Responding to the development, André Oliveira, 12, said: "It gives me lots of hope to know that the judges in the European Court of Human Rights recognise the urgency of our case." </p><p>"But what I'd like the most would be for European governments to immediately do what the scientists say is necessary to protect our future. Until they do this, we will keep on fighting with more determination than ever."</p>
‘Highly Significant'<p>The decision represents a "highly significant" step, <a href="https://www.glanlaw.org/about-us" target="_blank">GLAN</a> Director Dr. Gearóid Ó Cuinn said in a <a href="https://youth4climatejustice.org/" target="_blank">press release</a>.</p><p>"This is an appropriate response from the Court given the scale and imminence of the threat these young people face from the climate emergency," he added. </p><p>By suing the 33 countries all together, the youths aim to compel these national governments to act more aggressively on climate through a single court order, which would potentially be more effective than pursuing separate lawsuits or lobbying policymakers in each country.</p><p>If successful, the defendant countries would be legally bound not only to ramp up emissions cuts, but also to tackle overseas contributions to climate change including those of their multinational enterprises.</p>
‘Major Hurdle’<p>The <a href="https://youth4climatejustice.org/the-case/" target="_blank" rel="noopener noreferrer">countries targeted</a> include all of the European Union member states as well as Norway, Russia, Switzerland, Turkey, Ukraine and the United Kingdom, none of which are currently aligned with <a href="https://www.ecowatch.com/tag/paris-agreement">Paris agreement</a> target to limit global temperature rise to well below 2 degrees C (3.6 degrees F) and pursue a limit of 1.5 degrees C (2.7 degrees F).<a href="https://climateactiontracker.org/countries/" target="_blank" rel="noopener noreferrer"> </a></p><p><a href="https://climateactiontracker.org/countries/" target="_blank" rel="noopener noreferrer">Climate Action Tracker rates</a> most of Europe as "insufficient" in terms of its emissions reduction policies based on the Paris target, while Ukraine, Turkey and Russia are assessed as "critically insufficient" – meaning they are on track for a warming of 4 degrees C or higher.</p><p>The European Union has pledged to slash its emissions by <a href="https://ec.europa.eu/clima/policies/eu-climate-action/2030_ctp_en" target="_blank" rel="noopener noreferrer">at least 55 percent by 2030</a>. But the Portuguese youth plaintiffs are calling for cuts of at least 65 percent by 2030, a level that <a href="http://www.caneurope.org/energy/climate-energy-targets" target="_blank" rel="noopener noreferrer">European climate campaigners say</a> is necessary to meet the 1.5 degrees warming limit.</p><p> The 33 countries must each respond to the youths' complaint by the end of February, before lawyers representing the plaintiffs will respond to the points of defense. </p><p>"Nothing less than a 65 percent reduction by 2030 will be enough for the EU member states to comply with their obligations to the youth-applicants and indeed countless others," Gerry Liston, legal officer with GLAN, said in a press release.</p><p>"These brave young people have cleared a major hurdle in their pursuit of a judgment which compels European governments to accelerate their climate mitigation efforts."</p><p><span></span><em>Reposted with permission from <a href="https://www.desmogblog.com/2020/11/29/court-advances-landmark-youth-climate-lawsuit-against-33-european-nations" target="_blank">DeSmog</a>. </em></p>
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By Liz Kimbrough
Six grassroots environmental activists will receive the prestigious Goldman Environmental Prize in a virtual ceremony this year. Dubbed the "Green Nobel Prize," this award is given annually to environmental heroes from each of the world's six inhabited continents.
Kristal Ambrose, the Bahamas<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzI3MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MDM5NTk5MX0.fdMrrUqf0HvWq0Uh0Ii3mXxJczHPyN1jcnSsQoXoerE/img.jpg?width=980" id="b9e66" class="rm-shortcode" data-rm-shortcode-id="b8b8777f7964bb7100672b3be0abf3fe" data-rm-shortcode-name="rebelmouse-image" />
Kristal Ambrose. Goldman Environmental Prize
Chibeze Ezekiel, Ghana<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzM2MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MTgzOTE3OX0.KoEZr3oMPKbeG2uT8q-ZsGPOGtIZ3l6V6NXEK5U90FU/img.jpg?width=980" id="65224" class="rm-shortcode" data-rm-shortcode-id="6ec640a8ba56a4db22b57e4f8734a7a4" data-rm-shortcode-name="rebelmouse-image" />
Chibeze Ezekiel. Goldman Environmental Prize
Nemonte Nenquimo, Ecuador<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzM2Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwNzYxODYwM30.cys5ZsFGd75UcjybADGBPFt20jrzgrsFujoj_qMTK4E/img.jpg?width=980" id="96b5a" class="rm-shortcode" data-rm-shortcode-id="0778ab7334e3297e0ead52d5fd1499e5" data-rm-shortcode-name="rebelmouse-image" />
Nemonte Nenquimo. Goldman Environmental Prize
Leydy Pech, Mexico<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzQwNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkzOTYzOH0.uHlN2FQoJJ_KFJWTn4oL__lDyjA0-HDnxewBhwgQRVg/img.jpg?width=980" id="9ab07" class="rm-shortcode" data-rm-shortcode-id="ccc347126d4ce9ddbb3b9c1b4673391b" data-rm-shortcode-name="rebelmouse-image" />
Leydy Pech. Goldman Environmental Prize
Lucie Pinson, France<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzQxMS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2NzE0NTU1NX0.OutmX3sfl4pMaoYssTQ4zk7Y14_hans7-Z-0B0xsjfM/img.jpg?width=980" id="4bcd7" class="rm-shortcode" data-rm-shortcode-id="4bff14750dc0a70fc79e9484ea2bdbd4" data-rm-shortcode-name="rebelmouse-image" />
Lucie Pinson. Goldman Environmental Prize
Paul Sein Twa, Myanmar<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0NzQxNS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NDAyNjU0MH0.DHrKykngmcJyJ5rn4r91ANH7FmQ7Us6ZMEOis8yAzGY/img.jpg?width=980" id="8fa36" class="rm-shortcode" data-rm-shortcode-id="0e703d62288df00931cd678c861c6e0b" data-rm-shortcode-name="rebelmouse-image" />
Paul Sein Twa. Goldman Environmental Prize
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