Researchers Detail Oldest and Most Diverse Lizard Paleofauna Encased in Amber
March 4, 2016
Researchers have found lizards encased in amber that provides some interesting evolutionary insight into the reptiles that lived more than 99 million years ago. The researchers say that previously discovered reptiles in amber detailed just skin fragments, feet, and a partial tail of a gecko, but what they have discovered constitutes what they describe as the oldest and most diverse lizard paleofauna preserved in amber. The findings include fine details of soft tissue and bones.
The amber revealed multiple lizard species from five clades.
The researchers, Juan D. Daza (Department of Biological Sciences, Sam Houston State University), Edward L. Stanley (Department of Herpetology, Florida Museum of Natural History), Philipp Wagner (4Zoologische Staatssammlung München), Aaron M. Bauer (Department of Biology, Villanova University), and David A. Grimaldi (Division of Invertebrate Zoology, American Museum of Natural History) looked at 12 pieces of amber from Myanmar, formerly Burma, that feature detailed lizard parts from reptiles that got stuck in tree resin.
The amber is from the Cretaceous period. Computerized tomography (CT) scans were taken that garnered detailed internal structures of the reptiles in 3D. The specimens are multiple species from five clades of lizards, including Gekkota, Lacertoidea, Agamidae, and Chamaeleonidae.
From Science Advances- HRCT images of mid-Cretaceous lizards in Burmese amber. (C, D, and F to K) Letters correspond to those used for the same specimens in Fig. 2. (C) JZC Bu267; (D) JZC Bu1848; (F) MCZ R-190835; (G) JZC Bu1802; (H) JZC Bu266; (I) MCZ 190836; (J-A) JZC Bu1803; (J-B) digital endocast of the left maxilla of JZC Bu1803 including the tooth row; (K) JZC Bu154. an, angular; bc, basicranium; bo, basioccipital; ce, central; cla, claws; cor, coronoid; cr, cervical rib; cv, caudal vertebra; d, dentary; dc, distal carpal; ect, ectopterygoid; en, external nares; f, frontal; fe, femur; fi, fibula; hu, humerus; ib, innominated bone; int, intermedium; lp, lingual process; mc, metacarpal; mt, metatarsal; mx, maxilla; n, nasal; orb, orbit; pal, palatine; par, parietal; pbsph, parabasisphenoid; pf, postfrontal; ph, phalanx; pis, pisciform; pmx, premaxilla; po, postorbital; prf, prefrontal; psv, presacral vertebra; q, quadrate; r, rib; ra, radius; rad, radiale; sa, surangular; so, supraoccipital; sr, sclerotic ring; ti, tibia; ul, ulna; uln, ulnare; 1 to 5, manual digits; I to V, pedal digits.
Some of the findings confirm that 99-million-year-old geckos had adhesive toe pads like that of their modern day counterparts. They also determined that chameleons of the period lacked zygodactyly and lateral compression yet still maintained the projectile tongue of modern chameleons. Toes that projected forward in chameleons evolved much later. The complete paper can be read here on the Science Advances website.