Science behind Species Selection

Species Selection 

Most endangered or threatened species have declined due to a variety of human-derived stressors, including habitat degradation and loss, overharvesting, invasive species, pollution, and climate change. In other words, the species highlighted by Fossilized Houston are not threatened solely due to climate change effects (e.g., elevated temperatures, increased frequency and severity of storm events, drought, etc). To identify climate-threatened species for this project, we relied on a variety of sources including:


  • Published peer-reviewed scientific journal articles 

  • The IUCN Red List of Threatened Species ( 

  • Non-governmental organizations (e.g., The Nature Conservancy, World Wildlife Foundation) 


We reviewed all available research publications to determine if climate change-derived stressors contributed to a given species’ decline, or are likely to do so in the near future. We also searched for mathematical models estimating how long each of these species was predicted to survive. We specifically searched for “Population Viability Analyses” or “Time-to-Extinction” estimates (see Tag Lines section below).  


We followed up on these literature reviews through direct email communications with scientific experts on candidate Fossilized Houston species, many of whom authored the peer-reviewed journal articles described above.  


Our team then weighed all of the information we were able to gather to determine whether there was a reasonable scientific basis for identifying a given species as “climate-threatened”. Species with sufficient support were recommended to artists for rendering as Fossilized Houston images.      


Tag Lines 

Each Fossilized Houston species has a tag line, like “SOS” or “Nearly Gone”, based on our research of the scientific literature on that species (see Species Selection section above). We assigned these general tag lines based on the number of individuals or populations thought to exist. Species for which few individuals remain or which are now found in only a few places on Earth have more urgent tag lines. 


Some species, like the Small-toothed Sportive Lemur (Lepilemur microdon) have a more specific tagline, such as “Extinct 2080”. Tag lines that include a year are based on published peer-reviewed population viability analyses (PVA) or time-to-extinction (TTE) models. These estimates represent the average time to extinction predicted for a population given a variety of factors. Population biologists often provide results from multiple different models for the same species in a given paper, along with some measure of the uncertainty associated with each of their results. Our tag lines simplify the results of PVA or TTE models, and are intended to provide a rough estimate of how much time we may have left with a particular species. For example, we may share the planet with the Small-Toothed Sportive Lemur for roughly six more decades.

Selected Bibliography here



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