Revisiting Vermeij 1977

In a paper published in Paleobiology in 1977, Geerat Vermeij examined the Mesozoic reorganisation of shallow water marine communities using gastropod skeletal geometry and other kinds of data. Based on the evidence, Vermeij argued that predation and grazing had grown stronger and become more damaging to skeletons, driving gastropod shell evolution. Forty years after the paper was published, I spoke to Geerat Vermeij about the origins of his interest in this topic, his memories of fieldwork and what we have learnt since about the evolution of gastropod morphology.

Citation: Vermeij, G. J. (1977). The Mesozoic marine revolution: evidence from snails, predators and grazers. Paleobiology, 245-258.

Date of interview: 22 March 2017 (via Skype)

Hari Sridhar:  I would like to start by asking you a little bit about the origins of the ideas that went into this paper. What was your motivation to do the specific work presented here, in relation to your earlier research on this system?

Geerat Vermeij: When I went to Princeton, I concentrated in both biology and in geology. I was always interested in both living and fossil animals, and evolution in general. I had lots of field experience before I wrote this paper, and it occurred to me that what I was seeing in relation to predation could be applied to fossils. I noticed that these fossils, which I had been handling a lot, were not well-defended. That’s sort of how it all came to be. The first version, really, of this was published in Nature in 1975, where I talked about the distribution of left-handed and planispiral coiling, and then things went off from there.

HS: Stepping back a bit, could you tell me about how you got interested in molluscs and shells?

GV: My parents were very good natural historians in the Netherlands. When I came to the United States, at age nine, I was really infatuated with natural history. I always collected shells on the beach, but I became really interested in shells when people showed me material from Florida. It became an obsession and it remains one. It is a childhood interest that has never gone away.

HS: I want to talk about people who shaped your thinking about this piece of work. Can we go over the names of the people you acknowledge, to get to know a little more about how you knew them and how they helped?

GV: Yes. One person in the Acknowledgements was CW Thayer, who is Charles Thayer. We were graduate students together at Yale. I also knew him in 1976, when both of us were teaching at Friday Harbor in Washington State. Thayer was a very smart individual. He knew a lot about bivalves, and other things. Unfortunately, he died about 10 years after the paper. We had a lot of interaction about brachiopods and other topics, which was great. Sarah Woodin was at the University of Maryland, where I was at the time. She and I saw each other almost every day and talked about soft animals, which was her specialty.

There were others too, like Jeremy Jackson and David Meyer, who were also graduates with me at Yale, who were also very influential in helping me put together my thoughts.

HS: Can I go over the other names in the Acknowledgments?

GV: Sure.

HS: Robert Bakker

GV: Robert Bakker was also a student at Yale. I don’t really remember exactly how he might have contributed ideas to this paper, how our discussions went, but he was a very interesting vertebrate paleontologist and remains one today.

HS: Alfred Fischer.

GV: Alfred Fischer is one of my real heroes. He was a professor at Princeton, a real Renaissance man, a geologist who had enormous knowledge and experience with both biology and geology. He had big ideas, you know, large trends in the history of life and so forth. He was a great inspiration.

HS: Then there’s Jeremy Jackson, who you already spoke about. Douglas Morse.

GV: Doug Morse was a colleague of mine at University of Maryland who was very supportive of my work. Again, I couldn’t tell you how exactly he might have influenced what I did. Perhaps he read the paper. I honestly don’t remember.

HS: Norman Sohl.

GV: Norman Sohl was a curator at the Smithsonian. He worked on Mesozoic snails and oriented me a lot to the literature on the topic.

HS: Steven Stanley

GV: Steve Stanley was a colleague of mine, who was at Johns Hopkins. Steve and I have had chats over the years. He and I have, kind of, gone separate ways, and we disagree about ownership of this whole idea. But, nevertheless, I read a lot of his papers, and they were all very influential, and I cited a lot of them in my paper.

HS: Thomas Waller

GV:  Tom Waller was also a curator at the Smithsonian. He was very wise, worked on scallops, which I. I believe I cited; maybe more than one of his works. I’m sure I talked to Tom about this entire problem.

HS: Ellis Yochelson

GV: Same story. Yochelson was a curator at the Smithsonian. He worked on Paleozoic organisms. I had lots of discussions with him and he gave me insights into the Paleozoic literature.

HS: Edith Zipser

GV: Edith Zipser is my wife. She has been a very smart and a very wonderful person throughout my entire adult life.

HS: Could you give us a sense of what it was like to do this work? What was your daily routine? What do you remember about the work that led up to this paper?

GV: I taught at the University of Maryland at the time, but we went to the Smithsonian once a week, looked at the collection, and worked in the library. I gathered an enormous amount of information. During the summers, we spent time away, in all parts of the world, in Panama, in Jamaica, Guam, Southwest Africa, East Africa, all kinds of places. So, I had lots and lots of marine biological experience. And this paper was, basically, an exercise in synthesis. I worked on it for the better part of 1976, or at least the second half of 1976. The idea didn’t really occur to me to start writing a paper about this until, maybe, I was in Friday Harbor, in the summer.  I sent it off around late December, and it took about two and a half months for it to be reviewed. The reviews were extremely positive, and I never had any troubles with it.

HS: How did you decide to submit this to Paleobiology? Was that an obvious choice at that point?

GV: Yeah, that was an obvious choice. The journal had begun in 1975. I always wanted to publish in it because it was a new and upcoming journal from the Paleontological Society. And I expected and hoped it would be widely read.

HS: In response to my earlier question, you said ‘We’. Who else was with you when you were doing this work – visiting the Smithsonian and on the field trips?

GV:  Mostly, my wife, but also the lady who worked with me as an assistant, whose name was Bettina Dudley, who died last year, unfortunately. She did a lot of reading, a lot of working with me in the collections, and so on.

HS: At the time when the paper came out, do you remember how it was received?  Was it a paper that attracted a lot of attention?

GV: I think it got a lot of attention. I remember that, in early 1978, I was in London, and John Taylor, at the Natural History Museum in London, said, I would never have had the guts to write that paper. I think he was envious of it, in a way, but he said he could never have done it himself.

HS: Are you surprised by the kind of impact it’s had on the field? Do you have a sense of what it mostly gets cited for?

GV: I haven’t kept careful track of this. I think it gets cited for major evolutionary trends, as it should be. I was hoping it would have an impact like that, but you can never tell. It’s been gratifying, to be sure.

HS: Would you say that this has been one of the important landmarks in your career, both in terms of what it did for your career and in terms of the impact it had on your future research?

GV: Yes, I would.  Whether I like it or not, I think it’s probably my most cited work. I don’t know that for sure; I have never looked, and I don’t really care. But, yes, I see a lot of my subsequent research has been an elaboration of the ideas expressed in this paper. Several of my subsequent books have dealt with it and many, many papers have dealt with various issues related to it. So, yes, I would say it, together with one or two other papers, has really defined much of what I’ve done in my career.

HS: What are the other papers?

GV: Well, my original 1974 paper in Evolution on comparing the defenses of Indo-Pacific versus Western Atlantic tropical molluscs was very influential. In fact, it sort of led to the paper we’re talking about now. This whole comparative approach – geographical as well as temporal – has been, sort of, the thread of my career, really.

HS: Would you say that the main conclusions of the paper still hold true, more or less? I’d like to read a few lines that capture the main conclusion of this paper. You say, “In short, continental breakup and long-lasting favorable climate may have created conditions favorable to the evolution of skeleton destroying predators and well-armored prey and had far-reaching consequences for benthic marine communities as a whole. Whether the Mesozoic era differed fundamentally from the Paleozoic in these respects remains to be determined, and the problem of dormant adaptive breakthroughs is not yet satisfactorily solved.”

GV: Well, now, of course, I think a lot of that has been solved, more so than it was then, but I don’t really disagree with those conclusions. In looking at it again now, I’m actually surprised at how much I got right, to be honest. Together with other people, I’ve elaborated a lot of things. And some things have changed as well. For example, we now know that some of the escalation occurred earlier in the Paleozoic. We also know that the Mesozoic revolution itself is, probably, a two or more phase process, which we didn’t realize at the time. These are important nuances, but the basic conclusions, I think, are right.

HS: In the introduction of the paper, you say that, in this paper, you will expand upon the theme of how the intensity of predation has increased since the middle Mesozoic. And also, using evidence of skeletal geometry and other data, you will argue that predation as well as grazing has intensified and become more destructive to skeletons. And then, finally, you say that you will ask, mostly in vain, what triggered this Mesozoic reorganization? Why was it in vain then, and how much more have we learnt since that time?

GV: Basically, I wanted to answer that question, but couldn’t at the time. I just didn’t know the answer. I would love to have known the answer at the time. I think we have learned a great deal since. For example, I have suggested, and other people have, more or less, supported the idea, that large volcanic eruptions in the mid-Mesozoic introduced a lot more nutrients. I think some breakthroughs in metabolism have also made an enormous difference, and we’ve worked a lot of that out. There is  another thing that was missing in this paper:  it is descriptive, rather than explanatory. An awful lot of what we now understand – at least, I hope we do – is how escalation itself works, the process of natural selection and how it works in terms of enemy-related evolution. I think my best rendition of that is my 2013 paper called On Escalation in the Annual Reviews of Earth and Planetary Sciences.

HS: You say, “For the purposes of this paper, I shall here regard Bellerophontacea as belonging to the class Gastropoda.” Is the systematic position of this group better known today?

GV: It’s not better known. I still think they are Gastropoda, but, frankly, it doesn’t really matter very much. Even if they are Monoplacophora, as many people would maintain, they’re still single-shelled molluscs, and, functionally, they’re like gastropods. So, I don’t really care.

HS: You say, “The intriguing possibility that the advantages of remodeling in non-nacreous shells could have contributed to the replacement through time in many lineages of the nacreous type of structure with other forms of micro-architecture deserves further investigation.” Has that happened?

GV: Well, I used to think that Nacre was the primitive form of gastropod shell mineralogy. It is not. But what is true is that taxa that are capable of remodeling have certainly surged. And my basic point in that paper was that remodeling enables a lot of morphology to evolve that otherwise could not. That remains true. I’ve been surprised at how little work has actually been done by physiologists on how remodeling works. It’s something I point out to all my students all the time. It’s a daunting problem, but it’s an important one that hasn’t really been dealt with.

HS: You say that the most profound changes affecting these communities seem to have happened in physiologically favorable environments and not in physiological stressed environments.

GV: That remains the case.

HS: Do we know more about why that is so?

GV: Yes, very much. When I said physiologically favorable, I mean a high temperature, or high food availability, and access to it; meaning, metabolic access to it. That definitely remains true. It’s also true that refuges play an important role. Life has expanded into the refuges. But yes, I think it is in the, so called, favorable environments where these important metabolic invasions arose.

HS: You say, “Whether the Mesozoic era differed fundamentally from the Paleozoic in these respects” –  you are referring to continental breakup and long-lasting favorable climate – “remains to be determined, and the problem of dormant adaptive breakthroughs is not yet satisfactorily solved.” What has happened subsequently in this regard?

GV:  I referred you already to the volcanic eruptions, which are pretty much connected with continental breakup. And, I think we do understand something, maybe not about the exact timing, but we certainly do understand about these metabolic rates; for example, the evolution of endothermy. We now understand a great deal more about the evolution of land plants, and how that might have affected marine environments; most notably, the evolution of higher photosynthetic rate and angiosperms. That’s all work done by Kevin Boyce in the late 2000s and subsequently. So, I think a lot of those details have been worked out. I’m still not entirely sure why this stuff didn’t happen much earlier. I think that is a question we may never get to – at least I may never get to it – but it remains an interesting issue.

HS: Have you ever the paper was published?

GV: Yes, I have. I’ve looked at it – I also just looked at it today – but I have consulted it in the past just to make sure I said what I thought I did. Each time, I’m surprised how much I did say in that paper.

HS: When you read it today, did you find anything particularly striking about the paper?

GV: Yes, I made a lot of statements that were not incredibly well backed up. They turned out to be correct, but I did not have a lot of the documentation at the time.

HS: Would you count this as one of your favorites?

GV: You know, it certainly is one of the more important papers I’ve published. I’m not sure I would count it as my favorite, although it’s hard to know what that would even mean. I think it turned out to be important, and therefore, I suppose it must be one of my favorites. But, you know, life has moved on, and we’ve learned a lot since. That’s the way science works.

HS: What would you say to a student who’s about to read this paper today? Would you guide his or her reading in any way? Would you point them to other papers they should read along with this? And would you add any caveats to their reading?

GV: Well, I think it’s a paper of historical significance. If I were to tell them about the Mesozoic marine revolution, I would say, why don’t you take a look to see who has cited this paper and work backwards? That’s what I would tell them to do. And, they’ll find some important work, right away, from the last five years or so. That’s how I’d operate, I think.

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