Dr. Larry Martin
I would like to offer this brief essay about Larry Martin. He passed away on March 9th after a long and productive career as a Paleontologist, Professor, and Curator of the important fossil collections at the University of Kansas. He was publishing papers often, right up to the end. I have been studying his work for 10 years now, and I would like to mention and comment on contributions that he made. I want to acknowledge the value of what I know of his life work. I am determined to be fair, but I will not ignore disagreements that I had with him.
First of all, Larry Martin was on our side. He spent his life studying evolution, observing fossils, and we all agreed that dinosaurs and birds were closely related archosaurs. He was the lead dissenter from the consensus, and the lead advocate of hypotheses that birds were not dinosaurs. I value diversity in opinion and I get a little nervous whenever I hear unanimity. Here I would ask my fellow mainstream Paleontologists to consider that the differences we had with Dr. Martin were a little like factionalism within the same political party. We all pledged our allegiance to understanding the origin and evolution of birds, and thus we disagreed all the more fiercely on the strategies that would get us there.
Dr. Martin focused attention on and was inspired by Heilmann’s masterpiece, The Origin of Birds. I got my copy in order to follow Martin’s reasoning and, still to this day, it is one of the most masterfully arranged and illustrated natural history books of all time. It draws in data from every possible facet of Biology and presents it all with great joy and beauty. Unfortunately, Heilmann is dead wrong in concluding that coelurosaurs lack clavicles altogether and thus cannot be the ancestors of birds. By the time of Heilmann’s book, in 1927, Osborn had already published a specimen of Oviraptor with a furcula (in 1924) . Wrong though it is, this book is also shockingly prescient in advocating Beebe’s 1915 hypothesis of a ‘tetrapteryx’, or four-winged, stage in the bird lineage. There was no clear evidence for this until fossils of Microraptor came to light 73 years later. It was an uncannily accurate speculation.
I believe that Dr. Martin had a beneficial effect on the field. Those Paleontologists who have spent their careers designing rigorous, repeatable, and objective methodologies may have differed with Martin’s method of speculation and critique, but I think they wrote some papers they would not have written unless they felt the need to answer Martin. In the process, progress was made on quantifying the ‘temporal paradox’ issue, and everyone’s hypotheses became more precise and explicit. When a group of people agree with one another in general, their communications can leave many things implicit. Nothing could be left vague in the face of Martin’s dissent. If there had not been dissenters like Martin more mainstream workers may have gotten careless by making categorical statements about extinct animals, and presented the strongest conclusions as the only ones. After all, the phylogeny of dinosaurs is necessarily based on morphological analysis, and these data have been known to disagree with molecular phylogenies in living organisms.
Martin held that homoplasy, or convergent evolution, could confound cladistic analysis, and cited this fact in rejecting mainstream phylogenies that showed that birds were one type of dinosaur. Martin’s position was unsupported speculation to almost all Paleontologists, and perhaps an unwelcome defeatist position that implied that evolutionary history was ultimately unresolvable. Today there are well-supported examples of morphological cladistic analyses that appear to have been deceived by homoplasy. The morphological phylogeny of Livezey and Zusi , for example, placed Buttonquail and Mesites as sister groups within the Turniciformes, and Flamingoes within the Ciconiiformes. The later molecular phylogeny of Hackett et. Al, 2008 , incorporated more characters and found that these assignments were wrong, and were the result of convergent evolution. Flamingoes were actually genetically closest to Grebes (confirmed by another molecular study using 1500 gene loci ), Buttonquail were in Charadriiformes, and Mesites were a sister group to doves.
With incomplete data sets, morphological phylogenies of dinosaurs have made big mistakes, finding the Alvarezsauridae to be flightless birds at one point. This was the best – supported hypothesis when only advanced alvarezsaurs were known, but more basal fossils showed startling convergences with birds as the lineage evolved. Thus, Martin’s central criticism of the methodology of mainstream bird Paleontology was validated even as the fossil evidence began to turn against him in an absolutely overwhelming, and probably unprecedented, scale. It is also important to note that the logical solution to these criticisms was to incorporate more data into the cladograms, not to dismiss mathematically rigorous analyses. Dr. Martin never attempted to do that.
That brings us to Martin’s paper of 2004, A basal archosaurian origin for birds . Martin spent much of his career insisting that the characters in common between dromaeosaurs and birds were the result of convergences that obscured the true evolutionary history. I have heard few mention that, in this 2004 paper, Martin rather quietly gave up on that view. The discovery of Microraptor brought him to finally concede that dromaeosaurs are birds’ closest relatives. But in a very odd sentence he offered a “compromise to a long and heated debate”, by accepting that maniraptorans may be secondarily flightless birds, crediting Gregory S. Paul with this hypothesis. In this way Martin could maintain his insistence that birds are not dinosaurs: by deciding that both they AND all other maniraptorans descended from Longisquama – like ancestors instead of dinosaurs. A critic may note that it is odd to think of a “compromise” in an attempt to reconstruct a series of historical events. It may be a bit like saying “I will stop saying that the Confederacy won the Civil War, but I will not concede that the Union won. As a compromise, let’s say that France won it”. But, nonetheless, this demonstrates that Martin was open – minded enough to be persuaded by the evidence and to reverse himself on a major part of his hypothesis. This non – theropodan phylogeny for birds may in fact have been first suggested by Stephen Czerkas . It was certainly not proposed by Paul, who has never wavered from his insistence that birds evolved from dinosaurs.
Finally I would just mention that Dr. Martin’s anatomical interpretations of fossils, including the pelvic girdles of Archaeopteryx and Microraptor, and the skull of Sinornithosaurus, were idiosyncratic. I hasten to add, however, that they were apparently always supported by one or more of the co-authors of his papers. Nonetheless, here one must be blunt, Martin’s observations were contradicted by virtually all other anatomists who examined the specimens. These were the most troubling opinions Dr. Martin held, as they called into question the very reliability of anatomical observation, and no mutually agreeable, empirical, method for resolving such disagreements between experts ever arose.
Dr. Martin’s greatest contribution to this field may be doubt. We should remember that the best – supported hypothesis is only that, use contingent language, and not overplay our hands. This field attracts vehement opinion and intense debate. The latter is the good part, and Dr. Martin was eager to debate, decade after decade. But vehement opinion is a weakness in analysis. We must follow the data, but we must keep our heads up and look around as we do so.
I am merely a paleo researcher with no doctoral degree, and my contribution is far below that of Dr. Martin, as he went on excavating fossils, training students, and teaching earth history to hundreds of students for decades.
With great respect I bid Doctor Larry Martin farewell.
Osborn, Henry F. (1924a). “Three new Theropoda, Protoceratops zone, central Mongolia”. American Museum Novitates 144: 1–12. hdl:2246/3223.
B. C. Livezey, R. L. Zusi, Zool. J. Linn. Soc. 149, 1 (2007).
A Phylogenomic Study of Birds Reveals Their Evolutionary History
Shannon J. Hackett, Rebecca T. Kimball, Sushma Reddy, Rauri C. K. Bowie, Edward L. Braun, Michael J. Braun, Jena L. Chojnowski, W. Andrew Cox, Kin-Lan Han, John Harshman, Christopher J. Huddleston, Ben D. Marks, Kathleen J. Miglia, William S. Moore, Frederick H. Sheldon, David W. Steadman, Christopher C. Witt, and Tamaki Yuri
Science 27 June 2008: 320 (5884), 1763-1768. [DOI:10.1126/science.1157704]
McCormack JE, Harvey MG, Faircloth BC, Crawford NG, Glenn TC, et al. (2013) A Phylogeny of Birds Based on Over 1,500 Loci Collected by Target Enrichment and High-Throughput Sequencing. PLoS ONE 8(1): e54848. doi:10.1371/journal.pone.0054848
Martin, L.D. (2004). A basal archosaurian origin for birds. Acta Zoologica Sinica 50(6): 978-990.
Czerkas, Sylvia J. ed. (2002) “Feathered Dinosaurs and the Origin of Flight” The Dinosaur Museum Journal Volume 1. Blanding, Utah, USA. The Dinosaur Museum, August 1, 2002
I wrote an extensive reply here http://theropoddatabase.blogspot.com/2013/04/a-conversation-with-larry-martin.html including my actual discussion with Larry.
…but he called it an interclavicle, and nobody noticed till the 1990s.
I don’t think it’s actually common that morphological vs. molecular data disagree. What is common is that 1) the first molecular analysis of a large clade is the first phylogenetic analysis ever done of that clade, so its results disagree with the precladistic opinions in the literature; 2) when the morphologists try to gather those opinions, express them as a data matrix, and run an analysis, they end up just confirming the traditional hypotheses, because contrary data weren’t included – Livezey & Zusi did this. Later morphological analyses find different results; even without molecular analyses to compare, this has happened in the field of early-tetrapod phylogeny.
Keep in mind that it’s very hard work to compile a morphological data matrix. A morphological matrix of 1,000 characters x 50 taxa, and keep in mind this is a very unusually high ratio of characters to taxa, is a PhD thesis. A molecular matrix of 10,000 parsimony-informative characters x 50 taxa takes weeks if you have to sequence everything yourself, days if you can just download them from GenBank and only have to worry about alignment. That’s why nobody except Livezey & Zusi has tried to do a morphological analysis of Neornithes, and why nobody except Zack (2009, unpublished thesis) has tried to do one of Eutheria with a decent sample of Paleogene fossils. (The recent huge Science paper has a truly impressive character sample, but the taxon sample is puny.)
Finally, it’s common for subsets of molecular data to disagree, like mitochondrial vs. nuclear.
Barsbold (1983) noticed Oviraptor’s interclavicle was a furcula. Pedantic, but so are you. 😉
I’m not sure your characterization of analyses is accurate. Gauthier et al. used a ton of novel characters for squamates, but still found a topology disagreeing with molecular analyses. We have several morphological analyses of placental phylogeny, but none agree with molecular results. Livezey and Zusi seem as likely to be wrong due to miscoding (Mayr, 2007) than to morphology itself.
…Oh. I shouldn’t have disappeared.
Squamates: massive unexamined character correlation. The recent big combined analysis which uses the Gauthier et al. matrix almost mentions the problem, but doesn’t even try to do anything about it. 😦
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