Form and Faunas. Cenozoic climatic and environmental change. G404 Geobiology. Department of Geological Sciences Indiana University

Transcription

1 Form and Faunas Cenozoic climatic and environmental change Titanoboa cerrejonensis (painting by Jason Bourque)

2 Atmospheric circulation today Strong insolation at equator combined with isolated climate at the poles produces Hadley cells Intertropical convergence zone at equator results in high precipitation Subtropical highs result in bands of low precipitation Subpolar lows result in bands of higher precipitation

3 Modern annual variation in precipitation Department of Geography, University of Oregon

4 Modern ocean currents (surface) Circumpolar current (Office of Naval Research)

5 Modern biomes (WIkimedia Commons, Sten Porse)

6 Characteristics of Earth s modern climate Strong latitudinal gradient in temperature Isthumus of Panama, Africa and the Middle East block circum-equatorial currents Arctic Ocean and seas surrounding Antarctica allow for circum-polar currents and promote ice caps Wet tropics, dry subtropics because of vertical atmospheric circulation patterns Global mean annual surface temperature ( average) = 13.9 C (57.0F)

7 Paleogene geography ( 2010, Ron Blakey, NAU Geology)

8 Global temperature through the Cenozoic Oxygen isotope proxy for temperature Global mean annual temperatures at PETM 19.8C (leaf data) to 26.0C (isotope data) ( F) (Zachos et al., Science, 292: )

9 Climate in the Paleogene circles = no frost intolerant plants squares = palms triangles = cycads, gingers or tree ferns Eocene Metasequoia stumps, Axel Heiberg Island (photo by Greenwood) (Greenwood & Wing, Geology, 23:

10 Paleogene latitudinal gradient Plant data show that latitudinal gradient was weak (Greenwood & Wing, Geology, 23: )

11 Ocean currents in the Paleogene (Seibold and Berger, The Sea Floor)

12 Biogeographic movements of mammals at the Paleocene- Eocene thermal maximum (Hooker, Mammalian faunal change across the Paleoeocene-Eocene Transition in Europe).

13 Responses of organisms to changing climates How do species respond to changing environments? By locally adapting via natural selection or ecophenotypic plasticity; By shifting their geographic ranges; By extinction; Or by the interaction of 1 & 2. How do communities respond to changing environments? By coevolution via natural selection or ecophenotypic plasticity; By geographic range shifts; By extinction, total or selective; Or by the interaction of 1, 2 & 3.

14 Ecometrics - the study of organismal-environment interaction through traits taxon-free patterns of morphological trait variation as proxy for climate or environment taxon-free refers to traits that have a physical relationship to environment, regardless of taxonomic group Examples include tooth morphology and diet, locomotor mechanics, respiratory characters (especially in plants) (Polly et al, History Matters. Proc. R. Soc. B., 278: )

15 Levels of ecometric analysis and types of traits 1. The trait must be comparable across taxa and time (Polly et al, History Matters. Proc. R. Soc. B., 278: ) 2. The trait must be correlated with some aspect of environment 3. The mean of the trait in a community must be correlated with the same aspect of environment

16 Titanoboa cerrejonensis 1.5 ton boid snake from the Paleocene of Colombia UF/IGM 3, Dorsal view 5 cm UF/IGM 2, Anterior view UF/IGM 5, Anterior view UF/IGM 4, Anterior view Head, J.J., J.I. Bloch, A.K. Hastings, J.R. Bourque, E. Cadena, F. Herrera, P.D. Polly, and C.A. Jaramillo Giant boine snake from a Paleocene Neotropical rainforest indicates hotter past equatorial temperatures. Nature, 457:

17 Titanoboa s relatives Elapidae Elapidae Colubridae Viperidae Typhlopidae Cylindrophidae Boidae Photos from Greene, Snakes, Mystery in Nature. California

18 How big was Titanoboa? Regression of SVL on vertebra width P < 0.001, R2 = 0.7 Total body length: m +/ m (42 ft) Body mass: 1,135 kg (1.27 tons) Living anaconda: Living python: Record = 7 m, Average = 6.5 m Record = 9 m, Average = 6 m An adult Ball python slithering over a Titanoboa vertebra. (c) 2009, Jason J. Head (Graphic by Brady MacDonald (c) 2009, LA Times) Head, J.J., J.I. Bloch, A.K. Hastings, J.R. Bourque, E. Cadena, F. Herrera, P.D. Polly, and C.A. Jaramillo Giant boine snake from a Paleocene Neotropical rainforest indicates hotter past equatorial temperatures. Nature, 457:

19 Why was Titanoboa so big? Size, metabolism and temperature in poikilotherms* mass specific metabolism b is lower in larger organisms, placing limit on maximum size (B = base metabolic rate, M = body mass) Max size (Lmax) is function of temperature and base metabolic rate Record sizes for living poikilotherms Relative size is proportional to temperature * poikilotherm = body temp equal to environmental temp Makarieva, A.M, V.G. Gorshkov, and B-L. Li Temperatureassociated upper limits to body size in terrestrial poikilotherms. Oikos, 111:

20 Reptile paleothermometer Estimated temperatures at Cerrejon Minimum MAT for Titanoboa : C Minimum MAT for Cerrejonemys: C do18 Forams: C Cerrejón paleofloras: C (known underestimate) Head, J.J., J.I. Bloch, A.K. Hastings, J.R. Bourque, E. Cadena, F. Herrera, P.D. Polly, and C.A. Jaramillo Giant boine snake from a Paleocene Neotropical rainforest indicates hotter past equatorial temperatures. Nature, 457:

21 Latitudinal temperature gradient in the Paleocene Titanoboa Latitude Mean annual temperature Shellito, C.J., L.C. Sloan and M. Huber Climate model sensitivity to atmospheric CO2 levels in the Early-Middle Paleogene. Palaeogeography, Palaeoclimatology, Palaeoecology, 193:

22 Other giant reptiles of the Paleocene Palaeophis snake Gigantophis snake podocnemidid turtle Boid snake Drazindaretes turtle Agamid lizard (Head et al., in prep)

23 Scientific papers for further reading Eldrett, J. S., D. R. Greenwood, I. C. Harding, and M. Huber Increased seasonality through the Eocene to Oligocene transition in northern high latitudes. Nature, 459: Head, J.J., J.I. Bloch, A.K. Hastings, J.R. Bourque, E. Cadena, F. Herrera, P.D. Polly, and C.A. Jaramillo Giant boine snake from a Paleocene Neotropical rainforest indicates hotter past equatorial temperatures. Nature, 457: Polly, P.D., J.T. Eronen, M. Fred, G.P. Dietl, V. Mosbrugger, C. Scheidegger, D.C. Frank, J. Damuth, N.C. Stenseth & M. Fortelius History matters: ecometrics and integrative climate change biology. Proceedings of the Royal Society B, 278: Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292: