2011: Archaeopteryx Sesquicentennial Year in Review

Germany commemorated the 150th anniversary of Archaoepteryx with a 10-Euro silver coin, shown here on the WitmerLab cast of the Berlin specimen.

What a remarkable 150^th birthday year it’s been for Archaeopteryx! Sesquicentennial celebrations, commemorative coins and stamps, historical articles, and special exhibits would have been enough, but Archaeopteryx made headlines when a prominent study in the venerable British journal Nature announced that it might not be a bird after all. That study was rebutted by another prominent study, which was in turn rebutted at a prominent conference. If that weren’t enough, an entirely new specimen of Archaeopteryx—only the 11^th ever discovered—was announced. Let’s have a closer look at this very eventful year.

WitmerLab commemorated the 150th birthday by building a website offering free interactive 3D PDFs of Archaeopteryx skulls and skull bones.

Celebrating the Sesquicentennial
Back in January, a colleague knocked on my office door asking for the latest on bird origins for a lecture for his Comparative Vertebrate Anatomy class. It was during that conversation that I literally did the math: 2011-1861=150…holy crap, Archaeopteryx was discovered 150 years ago! I contacted my old friend and Archaeopteryx authority Peter Wellnhofer, as well as various museum curators, and, sure enough, the Germans were well prepared for this celebration of their natural treasure. I blogged here in January about the upcoming festivities, including exhibits at the Humboldt Museum in Berlin and the German mint issuing a commemorative 10-Euro silver coin (which, by the way, is beautiful…I just got mine). In association with my blog post, we put up an “Archaeopteryx Sesquicentennial Celebration” photo album on our WitmerLab Facebook page and have been adding to it throughout the year. Others (such as Dave Hone and Brian Switek) have also blogged about the 150^th birthday celebration and Archaeopteryx’s historical impact, and magazines such as Earth Science Ireland and Earth have run similar stories. WitmerLab celebrated the actual 150^th birthday (September 30^th) by launching a website hosting a series of open-access interactive 3D PDFs of various Archaeopteryx skulls and skull bones, as well as an accompanying post here. It would have been enough just to pause to honor the role that Archaeopteryx has played in the history of the debates on both evolution and the transition to birds. But in July, Archaeopteryx took center stage once again.

The holotype skeleton of Xiaotingia zhengi with Xu Xing, the lead author of the Nature article. (Photo provided to Witmer from Xu and used with permission.)

Archaeopteryx hits the headlines once again: It’s not a bird…or is it?
Nature published an article in late July written by Xu Xing and colleagues that not only reported a new feathered creature from China (Xiaotingia) but also unveiled a new phylogenetic analysis that moved Archaeopteryx out of the place it had held for 150 years as the most basal known bird to a new position as basically just another birdlike dinosaur. Archaeopteryx was no longer a bird! This was actually big news, being reported in the New York Times, Scientific American, and many other outlets. I had a bit of an inside scoop since I had reviewed the manuscript for Nature, wrote the accompanying “News & Views” commentary in Nature, and blogged about it here. The press coverage was pretty good, emphasizing that this new finding says more about the early evolution of birds than the place of birds among dinosaurs. It also gave many of us the opportunity to discuss how evolution actually works, showing that evolutionary origins are messy, hard to tease apart, and, as a result, controversial. That scientific volatility was given voice by Michael Lee and Trevor Worthy in an article in the Royal Society’s journal Biology Letters published in late October. They reanalyzed the data presented by Xu and colleagues using different phylogenetic methods (maximum likelihood and Bayesian inference), with the result of returning Archaeopteryx to the avian nest. But before Archaeopteryx gets too comfortable in that nest, Xu and colleagues responded to Lee and Worthy, this time from the podium at the annual meeting of the Society of Vertebrate Paleontology in Las Vegas in early November. Xu vigorously defended their original findings, criticizing Lee and Worthy’s reliance on maximum likelihood methods that don’t handle missing data well (datasets with fossils invariably include lots of empty cells on the spreadsheet). Moreover, Xu noted, the Lee and Worthy analysis lacks credibility because it didn’t recover well established groups such as deinonychosaurs or the pairing of Archaeopteryx and Wellnhoferia. The latter is significant because many researchers regard Wellnhoferia to be so similar to Archaeopteryx as to not merit separation as a different genus. Expect the position of Archaeopteryx to remain volatile…probably forever.

The new 11th specimen of Archaeopteryx (natural light at left, UV light at right). Photos by Helmut Tischlinger, courtesy of Dave Hone.

The best birthday present of all: a new specimen of Archaeopteryx!
A completely unexpected bonus in this sesquicentennial year was the announcement of a new, very nice specimen of Archaeopteryx! Only the 11^th specimen known, it has yet to be formally described, and it’s not clear (to me, anyway) whether it’s in private hands or a museum. Fortunately, Dave Hone has an excellent relationship with Helmut Tischlinger, who not only had access to the specimen but also took his characteristically amazing photographs, including some stunning ultraviolet images. It’s clearly an important specimen, with nice bone detail and feather impressions. I’d like there to be more skull, but the front of the jaws are preserved, and maybe further preparation will turn up more skull remains.

The edge of the 10-Euro commemorative coins is engaved with “Archaeopteryx – Zeuge der Evolution” — Witness Evolution. Again, the coin is on our Berlin specimen cast.

Archaeopteryx – Zeuge der Evolution
In closing, it’s hard to imagine a more eventful 150^th anniversary year. It hasn’t been just looking back at 150 years of history, but has also been very forward-looking as we evaluate new evolutionary hypotheses of relationships and examine new specimens. The edge of the 10-Euro commemorative coin is engraved with the phrase “Archaeopteryx – Zeuge der Evolution,” which translates roughly to “Archaeopteryx – witness evolution.” Indeed, the now-11 fossil specimens of Archaeopteryx abundantly bear witness to the complex evolution of birds and dinosaurs. But moreover, this sesquicentennial year has allowed us to witness Archaeopteryx’s own evolving role in these debates.

–Larry Witmer

Lee, M. S. Y., and T. H. Worthy. 2011. Likelihood reinstates Archaeopteryx as a primitive bird. Biology Letters doi: 10.1098/rsbl.2011.0884.

Wellnhofer, P. 2010. A short history of research on Archaeopteryx and its relationship with dinosaurs. in Moody, R. T. J., Buffetaut, E., Naish, D. & Martill, D. M. (eds) Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications, 343, 237–250.

Witmer, L. M. 2011. An icon knocked from its perch. Nature 475:458–459.

Xu, X., You H., Du K., and Han F. 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475:465–470.