PALEOGEOGRAPHY OF THE CARIBBEAN REGION: IMPLICATIONS FOR CENOZOIC BIOGEOGRAPHY MANUEL A. ITURRALDE-VINENT Research Associate, Department of Mammalogy American Museum of Natural History Curator, Geology and Paleontology Group Museo Nacional de Historia Natural Obispo #61, Plaza de Armas, CH-10100, Cuba R.D.E. MA~PHEE Chairman and Curator, Department of Mammalogy American Museum of Natural History BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY Number 238, 95 pages, 22 figures, 2 appendices Issued April 28, 1999 Price: $10.60 a copy Copyright O American Museum of Natural History 1999 ISSN 0003-0090 CONTENTS Abstract ....................................................................... 3 Resumen ....................................................................... 4 Resumo ........................................................................ 5 Introduction .................................................................... 6 Acknowledgments ............................................................ 8 Abbreviations ................................................................ 9 Statement of Problem and Methods ............................................... 9 Paleogeography of the Caribbean Region: Evidence and Analysis .................. 18 Early Middle Jurassic to Late Eocene Paleogeography .......................... 18 Latest Eocene to Middle Miocene Paleogeography .............................. 27 Eocene-Oligocene Transition (35±33 Ma) .................................... 27 Late Oligocene (27±25 Ma) ................................................ 31 Early Middle Miocene (16±14 Ma) ......................................... 31 Biogeographical Hypotheses and Caribbean Paleogeography ....................... 35 Continent-Island Vicariance: Model of Rosen .................................. 35 Passive Overwater Dispersal: Model of Hedges and Co-workers ................. 40 Preliminary Issues ........................................................ 40 Sources of Error in Estimating Times of Lineage Origins ..................... 43 Passive Transport and Cenozoic Surface-Current Patterns ...................... 45 Surface-Current Patterns and Flotsam Dispersal ............................ 45 Surface-Current Patterns and Paleogeography .............................. 45 Surface-Current Patterns and Proxy Data .................................. 48 Other Constraints ....................................................... 50 GAARlandia Landspan and Island±Island Vicariance: Model of MacPhee and Iturralde-Vinent .................................................... 52 Landspans, Vicariance, and Diversity Scenarios .............................. 52 Discussion ............................................................... 56 Conclusions .................................................................. 58 References ................................................................... 59 Appendix 1: Reconstructing Caribbean Paleogeography: An Analytical Guide ........ 72 Yucatan Peninsula .......................................................... 72 Northern Central America, Nicaragua Rise, and Western Jamaica ................. 73 Southern Central America ................................................... 75 Northwestern South America ................................................. 75 Aruba/Tobago Belt .......................................................... 75 Greater Antilles ............................................................ 77 Blue Mountains Block ...................................................... 80 Aves Ridge, Lesser Antilles, and Grenada Basin ............................... 84 Beata Ridge ................................................................ 87 Cayman Islands and Cayman Ridge ........................................... 87 Appendix 2: A Plate Tectonic Model of the Caribbean from Latest Eocene to Middle Miocene ............................................................... 87 2 1999 ITURRALDE-VINENT AND MACPHEE: CARIBBEAN PALEOGEOGRAPHY 3 ABSTRACT This paper* presents a series of detailed paleo- nected by a ``landspan'' (i.e., a subaerial connec- geographical analyses of the Caribbean region, tion between a continent and one or more off- beginning with the opening of the Caribbean ba- shelf islands) centered on the emergent Aves sin in the Middle Jurassic and running to the end Ridge. This structure (Greater Antilles 1 Aves of the Middle Miocene. Three intervals within the Ridge) is dubbed GAARlandia. The massive up- Cenozoic are given special treatment: Eocene±Ol- lift event that apparently permitted these connec- igocene transition (35±33 Ma), Late Oligocene tions was spent by 32 Ma; a general subsidence (27±25 Ma), and early Middle Miocene (16±14 followed, ending the GAARlandia landspan Ma). While land mammals and other terrestrial phase. Thereafter, Caribbean neotectonism result- vertebrates may have occupied landmasses in the ed in the subdivision of existing land areas. Caribbean basin at any time, according to the in- The GAARlandia hypothesis has great signi®- terpretation presented here the existing Greater cance for understanding the history of the Antil- Antillean islands, as islands, are no older than lean biota. Typically, the historical biogeography Middle Eocene. Earlier islands must have existed, of the Greater Antilles is discussed in terms of but it is not likely that they remained as such (i.e., whether the fauna was largely shaped by strict as subaerial entities) due to repeated transgres- dispersal or strict continent±island vicariance. The sions, subsidence, and (not incidentally) the K/T GAARlandia hypothesis involves elements of bolide impact and associated mega-tsunamis. Ac- both. Continent±island vicariance sensu Rosen ap- cordingly, we infer that the on-island lineages pears to be excludable for any time period since forming the existing (i.e., Quaternary) Antillean the mid-Jurassic. Even if vicariance occurred at fauna must all be younger than Middle Eocene. that time, its relevance for understanding the ori- The fossil record, although still very poor, is con- gin of the modern Antillean biota is minimal. sistent with the observation that most land mam- Hedges and co-workers have strongly espoused mal lineages entered the Greater Antilles around over-water dispersal as the major and perhaps the Eocene±Oligocene transition. only method of vertebrate faunal formation in the Western Laurasia (North America) and western Caribbean region. However, surface-current dis- Gondwana (South America) were physically con- persal of propagules is inadequate as an expla- nected as continental areas until the mid-Jurassic, nation of observed distribution patterns of terres- ca. 170 Ma. Terrestrial connections between these trial faunas in the Greater Antilles. Even though continental areas since then can only have oc- there is a general tendency for Caribbean surface curred via landbridges. In the Cretaceous, three currents to ¯ow northward with respect to the major uplift events, recorded as regional uncon- South American coastline, experimental evidence formities, may have produced intercontinental indicates that the ®nal depositional sites of pas- landbridges involving the Cretaceous Antillean is- sively ¯oating objects is highly unpredictable. land arc. The Late Campanian/Early Maastrich- Crucially, prior to the Pliocene, regional pale- tian uplift event is the one most likely to have oceanography was such that current-¯ow patterns resulted in a landbridge, as it would have been from major rivers would have delivered South coeval with uplift of the dying Cretaceous arc. American waifs to the Central American coast, However, evidence is too limited for any certainty not to the Greater or Lesser Antilles. Since at least on this point. The existing landbridge (Panaman- three (capromyid rodents, pitheciine primates, and ian isthmus) was completed in the Pliocene; evi- megalonychid sloths) and possibly four (neso- dence for a precursor bridge late in the Middle phontid insectivores) lineages of Antillean mam- Miocene is ambiguous. mals were already on one or more of the Greater We marshal extensive geological evidence to Antilles by the Early Miocene, Hedges' inference show that, during the Eocene±Oligocene transi- as to the primacy of over-water dispersal appears tion, the developing northern Greater Antilles and to be at odds with the facts. By contrast, the land- northwestern South America were brie¯y con- span model is consistent with most aspects of An- tillean land-mammal biogeography as currently * Contribution 2 to the series ``Origin of the Greater known; whether it is consistent with the bioge- Antillean Land Mammal Fauna.'' ography of other groups remains to be seen. 4 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 238 RESUMEN El propoÂsito de este trabajo es presentar una vieron brevemenmte conectadas por una ``land- serie de anaÂlisis paleogeogra®cos detallados de la span'' (proyeccioÂn de terreno) (es decir, por una regioÂn del Caribe, comenzando con la apertura de coneccioÂn subaeÂrea entre un continente y una o la cuenca del Caribe en el JuraÂsico Medio y ex- maÂs islas situadas fuera del lõÂmite de la plataforma tendieÂndose hasta el Mioceno Medio. Tres inter- continental), coneccioÂn que estuvo centrada en la valos del Cenozoico reciben un tratamiento es- entonces emergida Cresta de Aves. Esta estructura pecial: la transicioÂn Eoceno-Oligoceno (35±33 (Crestas de las Antillas Mayores y de Aves) se Ma), el Oligoceno TardõÂo (27±25 Ma), y el Mio- denominoÂ