Lauren Graniero, student at Texas A&M and STRI short term Fellow, just published another paper that helps us make sense of the significance of stable isotope ratios in skeletal material. Continue reading
As the debate on the age of the Isthmus of Panama matures we respond to an eLetter.
Taken from Science Advances
8 November 2016
We thank Erkens and Hoorn for their constructive comments. Like us, they believe that collaboration between biologists, geologists and paleontologists focusing on data and analyses is required to unravel the history of the Isthmus of Panama. We agree with Erkens and Hoorn that the Continue reading
The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.
Get the paper here Finnegan et al 2015 paleo baselines Science
Upwelling along the Pacific coast of Central America today occurs where the land drops to less than 500m. Low land allows the trade winds to blow across and push surface waters out to open ocean causing strong coastal upwelling.
In this paper we estimate the strength of upwelling in the Plio-Pleistocene Continue reading
As a PhD student I devised and developed a completely new technique for investigating paleoseasonality. Reconstructions of paleoenvironments often fail to understand the importance of the mean annual range of temperature (MART) in both oceanographic and biological contexts. The new technique, called the ‘zooid size approach’ makes use of the temperature-size rule in colonial bryozoans to estimate MART. The temperature-size rule is a universal phenomenon that states that body size decreases as temperature increases.
At the time, our understanding of the temperature-size rule was rudimentary and it was necessary to develop hypotheses on the mechanisms behind the rule and then test them under controlled culture and natural experiments, before finally applying the approach to fossil bryozoans to estimate MART’s in ancient seas.
The original paper published in 2000 presenting the technique can be downloaded here.
Now 10 years later with my ex-Phd supervisor Beth Okamura we review the approach along with the growing body of work that has since been published on the theme. We consider the general issue of why body size varies with temperature, explore the limitations of the approach and highlight its advantages relative to other proxies for palaeotemperature inferences.
Download the pdf of this new paper by clicking on the image.
Most people think Panama has two seas – the Caribbean and the Pacific. In fact it has three and they are each very distinct. This paper presents detailed hydrological measurements from the two seas along the Pacific coast of Panama: the Gulf of Panama and the Gulf of Chiriqui, and characterizes the environmental differences between them. Click on the image for the pdf of the paper.