Author: Jonathan Losos Page 42 of 130

Who knew there were so many fossil geckoes? In the first review of fossil geckodom in more than three decades, Juan Daza, Aaron Bauer, and Eric Snively examine 28 fossil geckos, providing new insights into whether the specimens can be confidently attributed to taxa. Some times, they can placed into extant genera, other times, especially for the older ones, it’s hard to say for sure just where the belong.

If nothing else, the fossils are cool and sometimes quite old, the most ancient, Cretaceogecko, dating back to the early Cretaceous.

This paper was part of a special of the Anatomical Record published last year, “New Advances In Morphology and Evolution of Living and Extinct Squamates,” which was previously discussed in these pages.

Here’s the abstract:

Gekkota is often interpreted as sister to all remaining squamates, exclusive of dibamids, or as sister to Autarchoglossa. It is the only diverse lineage of primarily nocturnal lizards and includes some of the smallest amniotes. The skeleton of geckos has often been interpreted as paedomorphic and/or “primitive” but these lizards also display a wide range of structural specializations of the postcranium, including modifications associated with both scansorial locomotion and limb reduction. Although the concept of “Gekkota” has been variously applied by different authors, we here apply a rigorous apomorphy based definition, recent advances in gekkotan morphology and phylogenetics, and diverse comparative material to provide a comprehensive assessment of 28 known pre-Quaternary geckos, updating the last such review, published three decades ago. Fossils evaluated include both sedimentary fossils and amber-embedded specimens. Known Cretaceous geckos are exclusively Asian and exhibit character combinations not seen in any living forms. Cenozoic gekkotans derive from sites around the world, although Europe is especially well represented. Paleogene geckos are largely known from disarticulated remains and show similarities to Sphaerodactylidae and Diplodactylidae, although resemblances may be plesiomorphic in some cases. Many Neogene gekkotans are referable to living families or even genera, but their geographic occurrences are often extralimital to those of modern groups, as is consistent with paleoclimatic conditions. The phylogenetic placement of fossil gekkotans has important repercussions for timetree calibration, but at present only a small number of fossils can be confidently assigned to even family level groupings, limiting their utility in this regard.

In a recent post, we discussed the description of two new Costa Rican anoles, but didn’t draw attention to the fact that all members of the A. pachypus species complex exhibit dewlap dichromatism, with the dewlaps of males and females differing within a species. Shown here are differences in A. tropidolepis (top) and A. pachypus (bottom). The images on the right are females and the left and center are males.

In a previous post, we discussed this phenomenon, but its explanation still escapes us. Interestingly, it occurs almost exclusively in mainland anoles.

Joe Martinez of the Museum of Comparative Zoology writes in: “I was recently contacted by Samantha Grantham, the collections manager of the Wenham Museum in Wenham Massachusetts, who would appreciate learning the identification of a lizard skeleton that resides in the Coffin Room of their Addams Family dollhouse. The dollhouse was constructed locally, presumably with artifacts that were readily available.

It appears to be an anole and Anolis carolinensis would have been available through the pet trade at that time. Anolis sagrei may have begun showing up in the pet trade as well by then. Can anyone give an authoritative identification?”

And want to learn more about the Addams Family Dollhouse? There’s a whole blog devoted to it!

McCranie and Köhler have just published an authoritative account of the 39 species of Honduran anoles. Rich in detail and thorough in coverage, this volume will be of interest to anyone interested in neotropical herpetology.

Harvard University Press’s description says it all: Caribbean members of this group have been intensively studied and have become a model system for the study of ecology, evolution, and biogeography, but knowledge of the anoles of Central and South America has lagged behind. In this landmark volume, veteran herpetologists James R. McCranie and Gunther Köhler take a step toward rectifying this shortcoming by providing a detailed account of the rich anole fauna of Honduras. Generously illustrated with 157 photos and drawings, The Anoles of Honduras includes information on the evolutionary relationships, natural history, distribution, and conservation of all 39 Honduran anole species. The work is the result of decades of study both in the field and in museums and is the first synthetic discussion of the complete anole fauna of any Central or South American country. Each species is described in great detail with locality maps. Bilingual (English and Spanish), extensively illustrated identification keys are also included.

Distribution maps are provided for all species.

Like all publications of the Bulletin of the MCZ and Breviora, the book is freely available as a pdf on the journal’s website. But a pdf just doesn’t look right on a bookshelf, not to mention getting soggy in the field. For those who really  want to get the most out of this volume, why not consider purchasing it from Harvard University Press for only $24.95 (not bad for a 280 page volume jam-packed with color photos!)? And it’s even cheaper on Amazon (currently $20.48).

On her own blog, Ambika Kamath explains that field work is often about surprises and unexpected mysteries. Check out A Macabre Start to My Time in Florida.

Photo by Thadaigh Baggallay

Thadaigh Baggallay writes: “I took this picture in Kaieteur National Park, Guyana. Anolis chrysolepis perhaps?”

Looks to me like whichever chrysolepis-type anole occurs in Guyana. Exactly a year ago today, we had a post on a new field guide to Guyanan herps by Cole et al. which probably would help. According to that guide, I believe the species would be A. planiceps. Any thoughts any one?

Little is known about the Central American twig anole, but it does have a beautiful dewlap! In recent years, what used to be known as A. pentaprion has been split into a large number of species, the most recently described of which is A. triumphalis. (Editor’s note: Gunther Kohler points out that this is one of the newly named species, A. charlesmyersi).

Here’s the backstory from the videographer who posted this on Youtube: Greetings Casa Alta Vista, Costa Rica. That video was shot about 15 feet above ground, on the guava wood handrail that goes up my stairs. Our house is a rustic style “pole” house, constructed from plantation grown gmelina and teak woods. We are located about 2 miles inland of the shores of Golfo Dulce , Costa Rica, at about 600 feet elev. in a mostly second growth seasonally dry rainforest. Dry season from Dec to April, then usually 300 inches of rain , a lot of which is in September-October usually. We are across the gulf from Corcovado National Park . Maybe 15 miles as the toucan flies. The area around the house was pasture up until about 20 years ago, but now pretty lush with second growth. Fairly undeveloped, and there is some primary growth surrounding us down in the “quebradas” or streams that are all around here. Down there we have stream anoles, and lots of snakes and critters. Saw a bushmaster down there once . Yikes. We also see slender anoles (I think) but they aren’t very “brown” and the yellow spot on the dewlap isn’t as prominent as the picture in my book . We also sometimes see the dry forest anole, which seems to trade off the territory of my deck railing system with the lichen anoles. We see green anoles down on some of the fruit trees we have planted as well. Amazing creatures all, they don’t seem fearful of us, and maintain eye contact . And will bite of course if they are provoked and can catch hold of you. I once had a full grown basilisk lizard that I was rescuing from some dogs bite me nicely on the hand. We have really a lot of all kinds of wildlife here. The birding is great, and we have a large troop of mono titi’s (squirrel monkeys) that occasionally traverse our back deck, peek in the windows, and move on to eat guabo beans in the trees surrounding our house. We’re built about 4 meters off the ground, not a treehouse , but kind of up in the trees .
My camera is new, and I will be posting other animal videos soon. And will try to get more anole videos.

Editor’s Update, 2/23/2015:

Here’s another clip of the same animal:

Photo by Cristian Castro Morales

AA reader Cristian Castro Morales has sent in this photograph of the little known Anolis huilae. He says: Male of Anolis huilae display their dewlap to ward off a possible predator or rival from his perch. This species is reported in Colombia in the departaments of Huila and Tolima.

Photo by James Christensen

Anolis auratus is one of the most widespread mainland anoles, with a range stretching from Costa Rica through much of northern top of South America on both sides of the Andes. It’s biology is surprisingly little known, though it is thought to be a grassland species; that and it’s morphological similarity to grass-inhabiting Caribbean anoles has led some to argue that this species is a member of the grass-bush ecomorph category.

Given it’s wide range in Colombia traversing the Andes, the species is ripe for investigation of geographic variation, and that is just what Martha Calderón-Espinosa and Leidy Alejandra Barragán-Contreras did, examining a large number of museum specimens in the collection of the Instituto de Ciencias Naturales, Universidad Nacional de Colombia. Their work was recently published in Acta Biológica Colombiana. The abstract is appended below, but to make a not-so-long story short, sexual dimorphism exists for several characteristics independent of body size (the sexes don’t vary in size), and these same characters vary geographically. What this means about variation in habitat use of the species across its range remains to be studied.

Abstract

Anolis auratus is a widely distributed species, from Costa Rica in Central America, through northern South America, including Colombia, Venezuela, northern Brazil, Surinam and the Guyanas. In Colombia, its widespread distribution across different life zones suggests that these lizards occupy different environments and exhibit different microhabitat use in different geographic areas. On the other hand, some observations suggest that this species prefers open areas, selecting grasslands over brushy areas, and thus, an alternative hypothesis is that microhabitat use is similar among different populations. In Anolis, body variables related to locomotion (body size and shape) define structural microhabitat use, so two distinct patterns could be expected in this species: conservative or highly variable body size and shape throughout the species distribution. To test these predictions, we characterized geographic variation in morphometric traits of this species in Colombia. Females and males were similar in body size, but exhibited differences in some variables related to body shape. These characteristics also varied among males and females from different regions, suggesting heterogeneous use of structural microhabitat, between sexes and among populations. As an alternative, phylogenetic divergence among populations could also account for the observed differences. Absence of ecological and phylogenetic data limits our ability to identify the underlying causes of this pattern. However, we provide a general framework to explore hypotheses about evolution of body size and shape in this species.

We’ve previously had both a photo and a video of egrets downing not-so-festive brown anoles, and here’s another example from Wild about Spain. Word on the street is that egrets can be major anole predators in some places.