David W. Krause is Distinguished Service Professor in Stony Brook University’s Department of Anatomical Sciences. For well over a decade he has led a groundbreaking field investigation of the fossils of the African island of Madagascar — a paleontologist’s paradise — due to the fossils’ state of preservation and the island’s role in the plate tectonic history of the Southern Hemisphere. Krause talks about the time capsule that is Madagascar, rife with the fossils of dinosaurs and so much more.
Q: Your 10 seasons of field work in Madagascar have yielded a wealth of fossils — 555 specimens from last year’s expedition alone. What makes Madagascar such a rich place for paleontologists?
We’ve been fortunate to unearth some of the most complete and best preserved specimens of fossil vertebrates (backboned animals including fishes, frogs, turtles, snakes, lizards, crocodiles, dinosaurs, birds, and mammals) from the Cretaceous of the southern supercontinent of Gondwana, mostly from a small field area in the Mahajanga Basin of northwestern Madagascar. Their completeness and preservation is owing to unusual conditions that we’ve been able to reconstruct from a close examination of the rocks in which the specimens were entombed (e.g., Rogers and Krause, 2007).
The climate in the Late Cretaceous appears to have been much like it is today in the same general area — hot and dry for much of the year, resulting in severe droughts and stressed environments, but extremely wet for a few weeks or months. In other words, the climate was highly seasonal. The relatively brief rainy season dumped 40-50 inches of precipitation on the area annually. This resulted in massive debris flows that, with milkshake-like consistency, churned their way down from the highlands in the southeast and made their way into the Mahajanga Basin, where we find the fossils, and then on to the Mozambique Channel (Rogers, 2005).
These debris flows covered everything in their paths, including the bones of animals that had died, whether months or days before, and perhaps even living animals. It is these debris flows that entombed the remarkable fossils that we’ve been discovering since 1993. Because of their rapid burial, many of the specimens are remarkably well preserved, to the extent that even non-bony tissues (e.g., keratin) are known (Schweitzer et al., 1999).
David W. Krause (right), with team members Joseph Groenke and Gina Sorrentino of Stony Brook University, examine remains of a sauropod dinosaur Sorrentino discovered in Madagascar.
Q: Talk about some of the most interesting and important finds you’ve made so far — what are your top four?
1) Well, first, I think discovering the skull of Majungasaurus crenatissimus back in 1996 ranks at the top. We knew there was a medium- to large-sized, meat-eating theropod dinosaur in the fauna because a French paleontologist by the name of Charles Depéret had described a couple of teeth and a few bone fragments of it back in 1896, a full century earlier. And we, in our expeditions of 1993 and 1995, had found literally hundreds more teeth and also more bones, including a nicely preserved premaxilla (Sampson et al., 1996). But finding the skull had become an obsession, and our patience (not really) and work were rewarded in 1996 when we uncovered an exquisitely preserved skull and lower jaws in a quarry that was littered with not-so-well preserved sauropod bones. The skull showed, without doubt, that parts of a skull of another dinosaur, long thought to be the only Gondwanan pachycephalosaurid, a dome-headed plant eater, were actually those of this meat eater; the skull solved what had become taxonomic and biogeographic enigmas. We described the skull in 1998 (Sampson et al., 1998) and since then have discovered several more skulls and, in fact, now have several partial skeletons as well, including one nearly complete one.
Interestingly, we also uncovered evidence revealing that M. crenatissimus was cannibalistic (Rogers et al., 2003). In 2007 we produced a large monograph on M. crenatissimus (see Sampson and Krause, 2007), making it the most thoroughly documented representative of a diverse group of Gondwanan theropod dinosaurs known as the Abelisauroidea.
Majungasaurus crenatissimus, a large meat-eating dinosuar found by Krause and team — considered his top discovery in Madagascar.
2) Rahonavis was also an extremely interesting and important discovery. Although we have since discovered more bones of this animal, the first and still most complete partial skeleton was found in 1995 in a huge quarry that yielded several skeletons of the new, large sauropod dinosaur named Rapetosaurus (Curry Rogers and Forster, 2000). This skeleton included much of the vertebral column, the pelvis, hind limbs, and part of a wing. When we first described Rahonavis (Forster et al., 1998), we considered it to be a bird, albeit an early but still very primitive offshoot in the avian radiation. It had feathers and several other features that were then considered diagnostic of birds, but it also had several very primitive features, including a huge, sickle-like, raptorial claw on the second toe of the hind foot, very much like that in Velociraptor, the dromaeosaurid theropod dinosaur of Jurassic Park fame. It was clearly close to the transition between dinosaurs and birds. Several more recent finds of dromaeosaurids, particularly in the Cretaceous of China and Argentina, however, show that they also had feathers and therefore have clarified the picture. Rahonavis was also a dromaeosaurid theropod, one that belonged to a particular group known as unenlagines otherwise known only from South America.
Rahonavis, found by Krause and team in a huge quarry in Madagascar. The enormous, sickle-like raptorial claw on the animal’s second toe calls to mind Velociraptor of Jurassic Park fame. Rahonavis belonged to a group of animals otherwise only known from South America.
3) Simosuchus was based on an exquisitely preserved, articulated skull and most of the skeleton found in 1998 by a Malagasy graduate student, Louis Laurent Randriamiaramanana. It is an extremely unusual crocodyliform that seems to break many of the rules of being crocodile-like. Instead of having a long snout, it had a pug-nose. Instead of having long, conical teeth with which to capture prey, it had leaf-shaped teeth, probably used to eat vegetation. Instead of having a long, laterally compressed tail, it had an extremely short, uncompressed one. Instead of having a few rows of bony plates in its skin like most of its close relatives, it was enveloped in them, resulting in a tank-like body; it even had bony shields on its legs. And on and on. The phenomenal preservation of this specimen in particular, but also several more recently discovered skeletons, prompted us to thoroughly document the anatomy of Simosuchus and make inferences about its relationships and functional morphology in a recently published, large, multi-authored volume (Krause and Kley, 2010).
Simosuchus, a crocodyliform, based on an exquisitely preserved specimen, that is decidedly uncrocodile-like — pug nose, leaf-shaped teeth, short tail.
4) Beelzebufo represents a different kind of discovery, one in which we were not able to find a single, reasonably complete, well-preserved “gee-whiz” specimen. Beginning in our first field season, we found bits and pieces of a monstrous frog and, knowing that it was huge, we kept referring to it as the “frog from hell.” Finally, in 2008, after 15 years, we decided to describe what we had, which consisted of 75 or so fragments, mostly from the skull (Evans et al., 2008). My colleague Cathy Forster, while working with us one day in the field, conjured up a name that was in keeping with our original description: Beelzebufo, which, translated literally from its Greek and Latin components, means “devil toad.” We estimated Beelzebufo to have been 16 inches long and to have weighed up to 10 pounds; it was, in fact, probably quite a formidable predator. In the last few days of our most recent field season (2010), we finally discovered articulated material, most of a skull, which we are now eagerly studying for more clues about the anatomy, relationships, and life habits of Beelzebufo. And this summer we intend to go back to the same site, hoping to find more of this same individual. [National Geographic News: Giant "Frog From Hell" Fossil Found in Madagascar]
A monstrous frog the team named Beelzebufo — “devil toad” — dwarfs the largest frog living on present-day Madagascar. Beelzebufo is thought to have measured 16 inches long — and weighed up to 10 pounds.
Q: What do these finds tell you about the supercontinent Gondwana and the controversial question of how and when it broke apart?
A lot. Our discoveries of vertebrate fossils from the Late Cretaceous of Madagascar continue to have profound implications for the biogeographic and plate tectonic history of Gondwana. In essence, if the pattern of the distribution of organisms is frequently the result of the development of geographic barriers to dispersal, one mechanism for the development of such barriers is plate tectonics, which during the Cretaceous resulted in the Gondwanan supercontinent breaking into various landmasses – mainly South America, Africa, Antarctica, Australia, Madagascar, and the Indian subcontinent. Animals that could not disperse across marine barriers were therefore left isolated on one or more of these subunits of the supercontinent to evolve (or go extinct) in isolation.
We now know that Madagascar has been physically isolated from all other major Gondwanan landmasses for over 85 million years; it’s been an island in the Indian Ocean for that long. It was therefore initially surprising to us to find vertebrate animals that had close relationships to taxa (organisms) that lived at roughly the same time near the end of the Late Cretaceous (roughly 66 million years ago), in both the Indian subcontinent and South America. This indicated a level of cosmopolitanism, to the exclusion of Africa, that had not been documented previously. It seemed, therefore, that much of the Gondwana supercontinent had remained connected for considerably longer into the Cretaceous than previously known.
In looking for ways to explain this cosmopolitanism, particularly to South America, we latched on to a paleogeographic reconstruction proposed by a group of geologists and geophysicists in 1999 that suggested a lingering connection between South America and Indo-Madagascar through Antarctica. Renewed assessment of this reconstruction, however, clearly shows that such lingering physical connections between Antarctica and Indo-Madagascar (the landmass including Madagascar, the Seychelles, and the Indian subcontinent) did not exist into the later stages of the Late Cretaceous (Ali and Aitchison, 2009; Ali and Krause, in press). Teaming up with geologist/geophysicist Jason Ali, I recently examined the best test cases among vertebrate animals for assessing physical connections between landmasses, those that were large and restricted to terrestrial environments (that is, those that were unlikely to have rafted or swum great distances) (Ali and Krause, in press). This pertains largely to dinosaurs and crocodyliforms, many of which were much less aquatic than the crocodiles of today. When we did this, we saw that the relationships of the taxa known from the latest Cretaceous of Madagascar and the Indian subcontinent revealed long ghost lineages, which simply means that their ancestors probably arrived on Indo-Madagascar much, much earlier than their current records would indicate. This may solve what has become a rather contentious issue over the last decade. It also points again to the need to find earlier records on Madagascar and the Indian subcontinent but also from these and other Cretaceous intervals on other Gondwanan landmasses.
Krause’s team works at a particularly rich Madagascar fossil site found in 2005 to contain fossils of ancient birds.
Q: Your research has yielded more than 80 peer-reviewed articles and book chapters; what main conclusions do they draw about the overall significance of the vertebrate assemblage you have been unearthing and analyzing?
The answer to this question, in part, goes hand-in-hand with the preceding one. The entire assemblage is providing new insights into the biogeographic history of many groups of vertebrate animals, as well as the timing and sequence of Gondwanan fragmentation. But another significant aspect of the vertebrate assemblage has to do with documentation of the anatomy of individual species, reconstructing the relationships of the various groups that they represent, inferring aspects of their functional morphology and behavior (i.e., what they ate, how they moved), and finding clues to reconstruct the paleoenvironment and paleoclimate in which they lived. Owing to the remarkable preservation and completeness of the majority of the specimens, many of the taxa now serve as the best-known representatives of major groups of vertebrates. I think this is fair to say particularly with regards to the dinosaurs (e.g., the abelisaurid theropod Majungasaurus crenatissimus, the noasaurid theropod Masiakasaurus knopfleri, the titanosaurian sauropod Rapetosaurus krausei) and the crocodyliforms (e.g., the notosuchians Simosuchus clarki and Mahajangasuchus insignis) but also to several other groups and several still-to-be-described taxa.
David Krause with a Malagasy child, at a dental clinic established by Krause’s team in Berivotra, Madagascar.
Q: Along with searching for fossils, you have made sure to leave something behind in Madagascar. Talk about the fund you have started to build schools and clinics in impoverished parts of Madagascar.
Because most of our work was concentrated in the same small field area year after year, we got to know the members of the community very well. From the very beginning of our work in Madagascar, the children seemed to follow us everywhere. They were fascinated by us, since foreigners were a rare sight in those early years. And they, in turn, were absolutely delightful, some of the happiest children I had ever encountered despite the fact that they live in horrible conditions in one of the very poorest countries in the world. We finally realized that they were with us every day of the week that we were traipsing around the badlands of Berivotra, and that they were therefore not going to school. We found out that they were not going to school because there was no school to go to; in fact, only a couple of the adults in the entire community had ever gone to school (they were from another area) and could read and write. Because the villagers in the community had helped us in various ways, we were looking for a way to repay them for their kindness. So, one day, I arranged for a meeting with the village leaders and asked them what we could do to help. Their #1 priority was an education for their children. When they informed me that we could start by hiring a teacher, which costs about $500 a year, it was a “no-brainer.” I went back to camp and we raised the teacher’s salary on the spot.
One thing led to another and in 1998 I founded an organization called the Madagascar Ankizy Fund (“ankizy” means children in the Malagasy language), whose mission is to provide education and health care to children living in remote areas of Madagascar . Since then we have built four schools in various parts of Madagascar (we will start building a fifth this summer), renovated an orphanage, dug many clean-water wells (thanks to Rotary International), and brought medical and dental teams from Stony Brook University into remote villages where there is no health care. Indeed, medical and dental care is virtually non-existent in many remote communities. It is actually very sad for us when we come back after a year or two of being away; some of the kids that we got to know very well had passed away from some easily treatable diseases. Respiratory infections, diarrheal diseases, and malaria are the biggest killers among young children, and almost all of the children also have major protein and iron deficiencies and rampant parasitic infections. And almost all of them have dental pain, the result of poor diets and no dental care. Our health care teams therefore provide life-saving care for both children and adults in these communities. In turn, our health care workers, many of them medical and dental students, have unparalleled, life-changing experiences, both personally and professionally. It’s a win-win situation.
Opening day at one of four schools, this one a primary school, built by David Krause and his team for the children of Madagascar. They had no school before this project.
Ali, J.R. & Aitchison, J.C. (2009) Kerguelen Plateau and the Late Cretaceous southern-continent bioconnection hypothesis: tales from a topographical ocean. Journal of Biogeography, 36, 1778-1784.
Ali, J. R., and D. W. Krause. In press. Late Cretaceous bio-connections between Indo-Madagascar and Antarctica: evaluation of the Gunnerus Ridge causeway hypothesis. Journal of Biogeography.
Curry Rogers, K. A., and C. A. Forster. 2001. The last of the dinosaur titans: a new sauropod from Madagascar. Nature 412:530-534.
Evans, S. E., M. E. H. Jones, and D. W. Krause. 2008. A giant frog with South American affinities from the Late Cretaceous of Madagascar. Proceedings of the National Academy of Sciences 105(8):2951-2956.
Forster, C. A., S. D. Sampson, L. M. Chiappe, and D. W. Krause. 1998a. The theropod ancestry of birds: new evidence from the Late Cretaceous of Madagascar. Science 279(5358):1915-1919.
Krause, D. W., and N. J. Kley (eds.). 2010. Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 10. Journal of Vertebrate Paleontology 30 (6, Supplement), 236 pp.
Rogers, R. R. 2005. Fine-grained debris flows and extraordinary vertebrate burials in the Late Cretaceous of Madagascar. Geology 33:297-300.
Rogers, R. R., and D. W. Krause. 2007. Tracking an ancient killer. Scientific American 296(2):32-39).
Rogers, R. R., D. W. Krause, and K. Curry Rogers. 2003. Cannibalism in the Madagascan dinosaur Majungatholus atopus. Nature 422:515-518.
Sampson, S. D., and D. W. Krause (eds.). 2007. Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 8, 184 pp. Journal of Vertebrate Paleontology 27 (2, Supplement).
Sampson, S. D., D. W. Krause, P. Dodson, and C. A. Forster. 1996. The premaxilla of Majungasaurus (Theropoda, Ceratosauria), with implications for Gondwanan paleobiogeography. Journal of Vertebrate Paleontology 16:601-605.
Sampson, S. D., L. M. Witmer, C. A. Forster, D. W. Krause, P. M. O’Connor, P. Dodson, and F. Ravoavy. 1998. Predatory dinosaur remains from Madagascar: implications for the Cretaceous biogeography of Gondwana. Science 280:1048-1051.
Schweitzer, M. H., J. A. Watt, R. Avci, C. A. Forster, D. W. Krause, L. Knapp, R. R. Rogers, I. Beech, and M. Marshall. 1999. Keratin immunoreactivity in the Late Cretaceous bird Rahonavis ostromi. Journal of Vertebrate Paleontology 19(4):712-722.