Scientists Find Feathered Dinosaur Tail Preserved in Amber

The following is an article re-posted from the BioLogos blog.  I’m thankful for the opportunity to share a story about this discovery. 

December 14, 2016 | By (guest author)

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On December 8, the journal Current Biology published an article that describes a special tuft of feathers found in a piece of amber only as big as a matchbox. What makes these feathers special is that they are attached to the tail of a juvenile dinosaur!
Since the 1860s, scientists have classified birds as closely related to and descended from dinosaurs, specifically a group called theropods, which includes familiar two-legged walking (bipedal) favorites like Tyrannosaurus and Velociraptor. In 1861, a transitional fossil was discovered that linked birds to dinosaurs. Named Archaeopteryx, or “ancient wing,” the animal was a crow-sized, bipedal reptile with a short snout, many teeth, and a long tail—with a full set of feathers! Since then, other fossils that share characteristics of both birds and dinosaurs have been unearthed, and birds are now considered to be the last survivors of the much larger dinosaur group. However, until quite recently, scientists thought most non-bird dinosaurs were scaly and hairless, like modern day lizards or snakes. Starting in the mid-1990’s, that began to change, as more feathers of varying complexity were found with dinosaur fossils. Scientists have now identified so many feathered dinosaurs and early birds that there is a published field guide.
So, what’s so special about finding a feathered dinosaur tail in amber? Many feathers, ranging in appearance from primitive to modern, have been found in amber, which is fossilized sap from extinct conifers. But, this is the very first recorded amber specimen to have feathers that are attached to a part of the dinosaur.

This is important for two reasons. First, it allows researchers to know what kind of animal grew those feathers. In this paper, the researchers conclude that the tail is from a non-bird theropod dinosaur, possibly a maniraptoran, based on vertebral number and morphology. The amber specimen contains 8 ½ articulated caudal vertebrae and is only a small part of the whole tail, which is estimated to have at least 25 vertebrae. In contrast to the long flexible tails of theropod dinosaurs, both early and modern birds have fused tail vertebrae. Several anti-evolutionary organizations have recently published articles casting doubt on whether the tail is from a dinosaur (see here and here and here). However, young-earth creationist scientists Todd Wood and Marcus Ross have criticized these responses, and argue that the evidence pointing to the dinosaur identification is very compelling.

Knowing the tail is from a dinosaur helps to place the feathers into a context and timeframe that is useful for studying how feathers evolved over time. For example, the feathers found on this dinosaur tail are not the type needed for flying; this suggests that these dinosaurs used their feathers for other purposes such as regulating temperature or courting mates.

Second, amber preserves aspects of ancient tissues that other fossils do not. Non-amber fossils usually contain only the squashed impressions of stiff, robust feathers. The delicate plumes trapped in this gem are preserved in intricate three-dimensional detail. One particularly exciting feature of these feathers is that they have an arrangement of barbs and barbules (the hooks that hold feathers together and create iridescence) that have not been seen before in either modern birds or dinosaurs, yet this arrangement fits nicely between two previously predicted stages of feather evolution.

Credit: Figure 4 from Xing et. al, © 2016 Elsevier Ltd.

Earlier, I referred to Archaeopteryx as a transitional fossil, but I want to clarify what that means when thinking about evolutionary change in groups of organisms. It is easy to over-simplify, and think that evolution acts in a linear fashion, like this:

Instead, evolution is better visualized as a branching tree. As lineages evolve and diversify, they become distinct from one another, which is represented by new branches. Not only does the tree branch but, over time, it is also pruned as species or entire lineages (e.g. all Tyrannosaurs) go extinct. The dinosaur tail in amber represents only a single point on a branch that is now extinct.

Remarkably, this is not the first discovery of feathers in amber published by this research team in 2016. In June, the team described two tiny partially feathered wings that belonged to an enantiornithine bird. The feathers are more modern in structure than those in the dinosaur tail but both specimens are from the same region of Myanmar. These samples are all about the same age, which suggests that non-bird feathery dinosaurs lived side-by-side with early birds with modern feathers, just as a branching-tree model of evolutionary history predicts.[1]

Discoveries like these amber-preserved feathers provide new insights into the evolutionary history of theropod dinosaurs and early birds, as well as an inkling of their coloration. They also demonstrate the power of evolutionary theory to make accurate predictions about what the fossil evidence will show. But even as these discoveries confirm the evolutionary link between birds and dinosaurs, they continue to reshape our assumptions about dinosaur appearance. If the vibrant birds we see today are living dinosaurs, why did we ever assume the extinct ones were dull-looking?

References & Credits

[1] The amber sample featured in this article has been dated to about 99 million years old. More information on how the sample was dated can be found here.

Special thanks to Joel Duff and Ryan Bebej for their assistance and advice in putting together this article.

Why get a PhD?

I’m currently writing  job applications, which is surprisingly reminiscent of working on my dissertation. Since I have a full-time position, I’ve been putting in at least 8 hours per day to stay on track, then working on the application materials early in the morning and late at night.

I couldn’t help but chuckle at this comic from The Upturned Microscope:

why-do-a-phd

Source link: https://upmic.files.wordpress.com/2012/06/why-do-a-phd

Apparently, not much changes post PhD, though it did take a few years before I wouldn’t wince at the sight of my study species and could restate my ‘passion for science’ without experiencing a sinking feeling in my gut.

Really, though…is there any other reason to do a PhD in the sciences besides having a passion that can be played out through research or teaching? It’s not for the money, it’s not for the prestige, and it requires a Herculean measure of perseverance.

Stay strong, PhDers, the world needs you.

Role models

Being a 4th year postdoc has encouraged me to start looking around and determining what I want to do ‘when I grow up’ – though I also firmly believe that I will never grow up.

Applying for grown-up jobs also has me dwelling on my 32-year old story; what I’ve done, where I’ve been, and how that stacks up against both my reasonable expectations and my wildest dreams.

In just the last two days, I’ve come across social media blurbs about three women (two young, and one amazingly well-preserved elder) whose stories I’ve found particularly compelling and have inspired some ‘what if’ self-reflection and sometimes downright whimsy.

First, Heather Anderson, 34 year old personal trainer from Michigan. This amazing, independent, woodsy rockstar crushed the unassisted through-hike record for the Appalachian trail in 2015. She traversed 2,168 miles in only 54 days – alone and walking to her own food drop sites (that’s 5 weeks, let me repeat that…5 weeks…faster than any other female has done this before. Mind blown. Oh, and she has the same category speed record for the Pacific Crest Trail, too. Miss Anderson fits the bill for a role-model young female athlete (she’s older than I am, yay!) who’s in it for the beauty of the experience and not the fame. You can read some of her story here.

Second, Jen Tinsman, Ph.D. student at Columbia University. Jen’s work is broadly in the areas of speciation and conservation genetics; she’s evaluating how anthropogenic habitat shifts affect population-level adaptation in her focal species. What really impresses me about Jen is that she studies lemurs in Madagascar! For those of you that know me, you’ll get why I think this is really cool. When I was really young (maybe 4-8 years old?) my response to the adult question “What do you want to be when you grow up?” was “I want to study lemurs in Madagascar”. Jen, you’re livin’ the dream. Keep up the amazing work. You can read more about Jen and her research here.

Finally, a nun who loves to run captured my attention this evening. Sister Madonna Buder competes in marathons and IRONMAN Triathlons, at the spry young age of 84! I’m so flabbergasted by this humble and devout dear that I’m not sure quite what to say. You can hear her talk about how she sees competing as a near cumpulsory way to use her God-given talent in a short video here. I hope she keeps on inspiring others to do all they can as long as they can…for a very long time.

These three have reminded me that ordinary people really can accomplish extraordinary things and that it’s never too late to pursue a dream.