Research Overview

How did the Isthmus of Panama change the world?

The Isthmus of Panama divided two oceans and connected two continents, setting in motion profound global changes. Terrestrial species from North and South America crossed paths and competed. New marine species evolved in the warmer Caribbean and cooler eastern Pacific, while others, isolated in a changed environment, went extinct.

What does a 20-million-year sequence of fossils in western Panama reveal about the spread of coral reefs in the Caribbean?

The sequence of geologic formations exposed throughout the archipelago of Bocas del Toro contains many assemblages of diverse marine fossils ranging from 20 million years in age to the present. Fossil coral reefs are almost entirely missing in these faunas until about three million years ago when they abruptly appear as the dominant component of all subsequent formations in the region.

Did the Isthmus of Panama close earlier than conventionally believed?

An isthmus is a narrow strip of continuous land joining two bigger land masses and separating two bodies of water. Fossiliferous sediments located from Colombia to Costa Rica over the last 20 million years allow us to estimate the depth of water in which they were deposited. A clear trend shows that the younger the sediments are the shallower was their depth of deposition. By about 15 million years ago, much land had emerged, leading some scientists to suggest the Isthmus of Panama had formed. However, gene flow between populations of marine species on either side of the future isthmus, delay of mass migration of land animals between the continents, and several other lines of evidence strongly indicate that a true isthmus did not fully form until three million years ago.

How did deep-water fossils from the Pacific appear in five-million-year-old Caribbean rock?

Some microscopic shelled marine animals called Foraminifera live in the sediment at the bottom of the ocean. Distinctive assemblages characterize different depths and different oceans. It was a surprise therefore when deep water foraminifera previously known only from the Pacific Ocean were found in the five-million-year-old Chagres Formation on the Caribbean coast of Panama along with many blue water fishes like marlin. We were forced to the conclusion that a marine strait must have existed across Panama at that time, another piece of evidence that the Isthmus was not closed 15 million years ago.


1958 B.Sc. (Honours) Geology, Kings College, London University

1963 Ph.D. Geology, University of Caen, Calvados, France and University of London

Selected Publications

2016 Odea, A, Lessios, H., Coates, A.G. and 32 others. The Formation of the Isthmus of Panama. Science Advances, v.2, No. 8, August 3.

2013 Coates, A.G. How old is the Isthmus of Panama? Bulletin of Marine Science. 89; 801-813.

2004 Coates, A.G., L.S. Collins, M.P. Aubry, and W.A. Berggren. The geology of the Darien, Panama, and the late Miocene-Pliocene collision of the Panama arc with northwestern South America. Geological Society of America, Bulletin 116 (11): 1327-1344.

2003 Coates, A.G., M.P. Aubry, W.A. Berggren, L.S. Collins, and M. Kunk. Early Neogene history of the Central American arc from Bocas del Toro, Western Panama. Geological Society of America, Bulletin 115 (3):271-287.

2000 McNeill, D.F., A.G. Coates, A.F Budd, and P.F. Borne. Integrated paleontologic and paleomagnetic stratigraphy of the upper Neogene deposits around Limon, Costa Rica: A coastal emergence record of the Central American Isthmus. Geological Society of America, Bulletin 112:963-981.

1996 Collins, A.G., Coates, A.G. Berggren, W.A. Aubry M-P and J. Zhang. The late Miocene Panamanian isthmian strait, Geology, 24;687-690

1993 Jackson, J.B.C., P. Jung, Coates, A.G and L.S. Collins. Diversity and extinction of tropical American mollusks and emergence of the Isthmus of Panama. Science 260: 1624-1626.

1992 Coates, A.G., J.B.C. Jackson, L.S. Collins, T.M. Cronin, H.J. Dowsett, L.M. Bybell, P. Jung, and J.A. Obando. Closure of the Isthmus of Panama: the near-shore marine record of Costa Rica and western Panama. Geological Society of America, Bulletin 104:814-828

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