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99 Million-Year Old Amber Fossils

A Mid-Cretaeous lizard. This one individual's long digits earned it the nickname "Nosferatu," after the long-fingered German movie vampire,

A Mid-Cretaeous lizard. This one individual’s long digits earned it the nickname “Nosferatu,” after the long-fingered German movie vampire,

When lizards prove too fast, slippery or downright squirrely to catch using other methods, herpetologists will sometimes turn to glue traps to snare their quarry. This technique is particularly useful when trapping elusive scansorial species (e.g. Bauer & Sadlier 1992, Ribeiro-Júnio et al. 2006), but is also proving useful for those of us who study fossil species. Sticky tree resin provides a naturally occurring glue-trap, and inclusions in fossilized resin, or amber, show that this material has been snaring and preserving small animals for many millions of years. Amber fossils are particularly important for three main reasons. Firstly, they preferentially preserve small, delicate specimens that are rare in the fossil record by dint of being too fragile to survive the fossilization process. Secondly, because they tend to be formed in tropical forested environments where decomposition happens rapidly and deposition is limited, they often contain snapshots of ecosystems that are rare in the fossil record. Finally, they preserve specimens in startling detail, often retaining soft anatomy at a resolution that no other fossilization process is capable of.

The term “Amber fossils” inevitably brings to mind images of frozen mosquitos, stuffed to the eyeballs with DNA-rich dinosaur blood and, while it is true that an enormous amount of arthropod diversity has been recovered from amber fossils, lizards have also been found in fossilized amber, from three continents and across six horizons that span 100 million years. Last year this blog discussed a series of anoles in amber that were featured in an impressive study by Sherratt et al. (2015) which documented the presence of ecomorphs 20 million years ago in the Hispaniola and Mexico. These fossils allow us to see directly into the past, and in the case of anoles, it was possible to document the early morphological diversification into some of the five basic ecomorphs (although, not all of them fitted in such categories).

amber1Earlier this month, a paper in Science Advances revealed the oldest amber lizard assemblage known to-date. This work is the result of teamwork between Ed Stanley, Phillip Wagner, Aaron M. Bauer, David Grimaldi and myself (Juan Diego Daza). We document the remains from 12 lizards that lived 99 million years ago in a tropical forest in an area of what is today Myanmar. Most modern lizards are pretty easy to identify to at least to family level–skinks have cycloid scales, geckos have toepads (not all), lacertoideans tend to have square scales, etc.–so naturally, you start looking for these traits in order to identify these animals. When I learned from my mentor, Dr. Richard Thomas, to use plastic bags in the field to collect lizards, these bags can be labeled and this makes sorting easy after a day of work. I remember the day that when we all met at the American Museum of Natural History with David Grimaldi; he started to bring plastic containers with small amber inclusions. It was like taking a Herpetology exam, and we kept asking each other, “what do you think it is?” You could only hear our wild guesses–gecko, skink, anguimorph, teiid, agamid–but none of us was entirely sure. This is because when these lizards were trapped, they looked very different to their modern relatives.

To determine the identity of these animals, we decided to look deeper, using a combination of light microscopy and high-resolution Computed Tomography (CT) to extract as much data from the specimens as possible.

Anole March Madness 2016!

Anole MM16Are you ready for March Madness?! No, not the basketball tournament… this year we are staging the very first Anole March Madness! We should acknowledge that we came up with this idea after following the popular Mammal March Madness for the past couple of years and feeling a little left out.

What is Anole March Madness? Just like the basketball tournament, we start with 32 of the best teams from 4 regions. The groups doing battle will be Mainland (Central America and South America) versus Island (Greater Antilles and Lesser Antilles). The rules are simple, if a lizard wins a bout it advances, if it loses it is out of the tournament.

 

Anole March Madness

Anole-March-Madness: download this pdf, fill in the text boxes, play along!

Don’t worry, no animals will be harmed in any way during this tournament. In fact, the matches are entirely fictional and come from the imaginations of AA contributors Kristin Winchell, Martha Muñoz, and Pavitra Muralidhar. We will pick the winners of each bout based on what is known about the morphology, ecology, and behavior of each species and will give a full recap of the (fictional) battles every few days.

Do your best to predict the winner of each match, and ultimately the champion! Fill in the empty text boxes in the PDF of the bracket above and pick your winners for each match. Take a photo of your completed bracket and tweet it with #AnoleMM2016 so we can all see your picks! You earn 1 point for each correct match in the first round (round of 32), 2 points in the second round (Sweet 16), 4 points in the third round (Elite 8), 8 points for the fourth round (Final 4), and 16 points if you guess the champion. Keep score and let us know how you’re doing! First matches will be posted in a few days. The Championship match will be on April 4th.

Now, meet the teams!

Another Case of Green Anole – Brown Anole Mating

sagrei carolinensis mating

A common question is whether green anoles (A. carolinensis) and brown anoles (A. sagrei) can interbreed. I am unaware of any hybrids between the two species, and given their long evolutionary separation, it seems unlikely that they could reproduce successfully. Nonetheless, occasional reports of interspecific matings are made, and here’s another.

Mitchell Gazzia posted this photo on his Facebook page, and provided these details:

Took place in late June of 2012 in Melbourne, the Lake Washington area in Brevard County…very close to the intersection of Lake Washington and Turtlemound roads.

A New Genus and Five New Species of Fan-Throated Lizards

 

Dewlap morphology and colouration of Fan-throated lizards. Clade 1: A. Sarada darwini sp. nov., B. Sarada deccanensis comb. nov., C. Sitana superba sp. nov.; Clade 2: D. Sitana spinaecephalus sp. nov., E. Sitana laticeps sp. nov.; Clade 3: F. Sitana ponticeriana, G. Sitana visiri sp. nov., H. Sitana cf. bahiri. Scale bar = 10 mm

Dewlap morphology and colouration of Fan-throated lizards. Clade 1: A. Sarada darwini sp. nov., B. Sarada deccanensis comb. nov., C. Sitana superba sp. nov.; Clade 2: D. Sitana spinaecephalus sp. nov., E. Sitana laticeps sp. nov.; Clade 3: F. Sitana ponticeriana, G. Sitana visiri sp. nov., H. Sitana cf. bahiri. Scale bar = 10 mm

V. Deepak and his colleagues from five different institutions in India have published a revision of the systematics of fan-throated lizards in India. This work nicely expands on the project of figuring out the diversity of this clade of magnificent lizards, following the description of two new species from Sri Lanka last year.

I’ll be writing more about this paper and these lizards in weeks to come, but for now, here’s a figure from the paper, and below, the abstract!

Abstract

We revise the taxonomy of the agamid genus Sitana Cuvier, 1829, a widely distributed terrestrial lizard from the Indian subcontinent based on detailed comparative analyses of external morphology, osteology and molecular data. We sampled 81 locations spread over 160,000 km<sup>2</sup> in Peninsular India including type localities, which represented two known and five previously undescribed species. Based on general similarity in body shape and dewlap all species were hitherto identified as members of the genus Sitana. However, Sitana deccanensis and two other morphotypes, which are endemic to north Karnataka and Maharashtra in Peninsular India, are very distinct from the rest of the known members of the genus Sitana based on their external morphology and osteology. Moreover, members of this distinct morphological group were monophyletic in the molecular tree, and this clade (clade 1) was sister to two well-supported clades (2 and 3) constituting the rest of the Sitana. The interclade genetic divergence in mtDNA between clade 1 and clades 2 and 3 was 21-23%, whereas clade 2 and clade 3 exhibited 14- 16% genetic divergence. Thus, we designate a new genus name “Sarada” gen. nov. for species represented in Clade 1, which also includes the recently resurrected Sitana deccanensis. We describe two new species in Sarada gen. nov. and three new species in Sitana. Similarity in the dewlap of Sitana and Sarada gen. nov. is attributed to similar function (sexual signaling) and similarity in body shape is attributed to a similar terrestrial life style and/or common ancestry.

Research on How Lizard Brains Work During Aggressive Encounters

 

Jaramillo uses a cryostat to process sections of lizard brain as part of her research

From the Trinity University newspage:

Leaping Lizards
Tuesday, March 8, 2016

Student researcher Maria Jaramillo lands Sigma Xi grant studying green anole lizards

by Carlos Anchondo ’14

Two male green anole lizards meet in the forest. One lizard has infringed on the territory of the other, who now feels threatened. In a bout of competition, the lizards extend their dewlaps, the flaps of skin beneath their lower jaw, and a faceoff ensues.

Observing this aggressive act, neuroscience major Maria Jaramillo ’17 pondered how the dewlap is processed as a stimulus in the lizards’ brains. She then compared this hostile social behavior with a non-social interaction, like a lizard’s observation of a leaf. How does the lizard’s brain handle each interaction? At what point and why is the brain more active?

To answer these questions, Jaramillo applied for and was awarded a $1,000 grant from Sigma Xi, The Scientific Research Society. The grant money will be used to purchase antibodies, used for immunocytochemistry, as well as other supplies like microscope slides. Jaramillo studies in the lab of biology professor Michele Johnson, a researcher of the evolution of lizard behavior, and collaborated with Johnson during the grant proposal.

“I find the brain very interesting because it controls everything that we do,” Jaramillo says. “I love to study lizards because the wild environments they live in provide all kinds of stimuli, and I want to understand how they process it all.”

For the study, Jaramillo recorded a video of a green anole lizard exposing its dewlap and edited the video, scrambling the pixels of the lizard but maintaining the exact same colors and movements. After removing the social context, Jaramillo analyzed a lizard’s reaction to the modified video in comparison to its reaction to the original. She also tested two lizards together and then played the video without the lizards as an additional control. The lizards were placed in arenas, and Jaramillo observed them using GoPro cameras.

Jaramillo was notified in December 2015 that she had received funding and couldn’t believe the news. She excitedly called Johnson to share her elation, as Jaramillo had been turned down for the grant during the previous application cycle.

“This was a super cool process because Dr. Johnson and I literally built this project together,” Jaramillo says. “I did a lot of the decision making and, even though lizards are not what I am going to study for the rest of my life, it has given me a lot of research experience where I have worked directly with a professor.”

Applying twice for the grant meant that Jaramillo and Johnson received feedback from Sigma Xi evaluators following the initial application. Jaramillo says she was not discouraged after being rejected, but eager to learn how best to improve her chances. A peer tutor for Johnson’s biology class, Jaramillo encourages other not to give up and to “just keep trying.”

From Katy, Texas, Jaramillo plans to pursue medical school after Trinity. Her motivation is to help others with their medical needs and keep them in good health. She says that she has always loved science, and views medicine as a rewarding way to put her interests to good use.

“Health is the thing everyone needs to survive,” Jaramillo says. “For someone who wants to go into medicine, understanding how to conduct research like this is critically important. Studying at Trinity has made me sure that I want to attend medical school and become a doctor.”

Carlos Anchondo is a writer and editor for University Marketing and Communications. He is a 2014 Trinity graduate and can be found on Twitter at @cjanchondo or at canchond@trinity.edu.

Amazonian Green Anole Fails to See the Cryptic Cricket

punctatusThe caption says: At first look this image may just look like an Amazon green anole (Anolis punctatus) climbing a tree; but look a little closer… there is a cryptically coloured cricket fooling the predatory eyes of the lizard. Jack Mortimer Photography

On the importance of Dorsal and Tail Crest Illumination in Anolis Signals

With a flurry of recent attention investigating how background light may influence the signalling efficiency of Anolis dewlaps (1,2,3,4), particularly those inhabiting low-light environments where patches of sunlight appear at a premium, it occurred to me that extended dorsal and tail crests may fall under similar selection. Below are some photos of Puerto Rican crested anoles (Anolis cristatellus) – a species in which males exhibit an enlarged tail crest and the ability to voluntarily erect impressive nuchal and dorsal crests during aggressive interactions (the mechanisms of which are detailed in this previous AA post) – that show how crests may contribute to signalling.

IMG_3833

I have no doubt this thought has crossed the minds of many anole scientists before, particularly those current graduate students so successfully studying A. cristatellus and familiar with their ecology and behaviour (namely Alex Gunderson, Kristin Winchell, Matt McElroy, and Luisa Otero). Dewlaps are undoubtedly of primary importance to anole signalling and communication, but what are people’s general thoughts on the relative importance of other morphological features?

IMG_3842

Anole Barely Moves While Snail Speeds Past

Anyone who studies animals behaving in their natural environments knows just how long they can spend doing nothing much. This is most definitely true of anoles as well. My colleague Jon Suh learnt this first hand last summer while working with me on Anolis sagrei in Florida. I think his video (from data he collected on lizard display variation, and sped up by 500%) perfectly captures what it feels like to spend a long time watching a lizard doing almost nothing.

Crayons, Anoles, and a College Education

Writing on the blog Cultured Vultures, Karl Koweski reports on a community college classroom exercise that involves coloring in anole ecomorphs and Caribbean anoles with different colored crayons. Surprisingly, he’s not thrilled about it.

Another Anole Amputee Doing Just Fine

I’m always amazed by the ability of anoles to survive–even prosper!–with dramatic injuries. How could a lizard get by missing half of a hind leg? How does it capture prey or escape predators? Display credibly? But they do. We’ve reported incidents of three-legged lizards before, and are always looking for more examples.

The photo above is a fine example, reported by Karen Cusick on Daffodil’s Photo Blog. The brown anole also had a mysterious dent on its site. Must have been a traumatic event.

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