The Lepidosaurian Ear: Variations on a Theme

Today, Lepidosauria encompasses more than 9,000 species of lizards, snakes, and amphisbaenians (Squamata), as well as the New Zealand Tuatara, Sphenodon (Rhynchocephalia). In many lizards, an efficient tympanic middle ear and an effective inner-ear compensatory mechanism permit acute hearing across a range of frequencies. Sphenodon lacks a tympanic membrane, but this is the result of secondary loss. Fossils of stem lepidosaurs and early rhynchocephalians indicate that the ancestral lepidosaurian middle ear was tympanic, although the compensatory mechanism was probably rudimentary. Derived rhynchocephalians like Sphenodon lost the tympanic ear, possibly in association with feeding specializations, whereas squamates improved it by developing a more efficient compensatory window. However, the timing of this change is uncertain as the earliest lizard fossils are uninformative in this respect. Lizards from the Early Cretaceous onward show the derived condition. Squamates are morphologically and ecologically diverse, and some specialized lifestyles have affected ear anatomy. Among extant squamates, the only obligate marine swimmers are sea snakes, but in the Cretaceous, mosasaurs dominated the marine niche. These aquatic lizards show a middle ear morphology analogous to that of extant marine turtles (bulla-like quadrate, expanded extrastapes, loss of the tympanum?). Loss of the tympanum also occurs in squamate burrowers but in conjunction with the possession of a robust stapes with an enlarged footplate and, frequently, reduction or modification of the compensatory mechanism. Ears of this type are found in the enigmatic Cretaceous Sineoamphisbaena and in amphisbaenians from the Eocene to the present day. Where known, the ears of early snakes more closely resemble those of burrowers than swimmers

The biomechanical role of the chondrocranium and sutures in a lizard cranium

The role of soft tissues in skull biomechanics remains poorly understood. Not least, the chondrocranium, the portion of the braincase which persists as cartilage with varying degrees of mineralization. It also remains commonplace to overlook the biomechanical role of sutures despite evidence that they alter strain distribution. Here, we examine the role of both the sutures and the chondrocranium in the South American tegu lizard Salvator merianae. We use multi-body dynamics analysis (MDA) to provide realistic loading conditions for anterior and posterior unilateral biting and a detailed finite element model to examine strain magnitude and distribution. We find that strains within the chondrocraniumare greatest during anterior biting and are primarily tensile; also that strain within the cranium is not greatly reduced by the presence of the chondrocraniumunless it is given the same material properties as bone. This result contradicts previous suggestions that the anterior portion (the nasal septum) acts as a supporting structure. Inclusion of sutures to the cranium model not only increases overall strain magnitudes but also leads to a more complex distribution of tension and compression rather than that of a beam under sagittal bending

An aggregation of juvenile Youngina from the Beaufort Group, Karoo Basin, South Africa

Main articleAn assemblage of five fully-articulated juvenile skeletons of Youngina has been recovered from the Late Permian strata of the south-western Karoo Basin. These 12-cm-long skeletons are not only the first articulated juveniles of this taxon, but also the oldest yet found in the Karoo Basin. They are preserved in overbank mudrocks of the Hoedemaker Member (Beaufort Group, Adelaide Subgroup) on the farm Leeukloof 43 in the Beaufort West district. Although they are estimated to be some three million years older than previously described Youngina, these specimens show no significant skeletal differences. The high degree of articulation and the spatial arrangement of these skeletons in a dish-shaped hollow is compelling evidence for them having huddled together within an underground burrow. Taphonomic analysis of associated fossils indicates that this was probably a mechanism to reduce water loss during drought on the ancient Karoo floodplains .Non

Achieving the Dream and Four-Year Institutions: Perspectives from Three Houston Colleges

This report examines the experiences of three Houston area four-year universities that are participating in Achieving the Dream, a national initiative designed to use data-driven decision making to promote student success, especially among low-income students and students of color. Each of these universities is a minority-serving institution, two are Historically Black Colleges or Universities and one is a Hispanic Serving Institution

Technical Assistance: Coach and Data Facilitator Support Among Texas Colleges

The goal of this research brief is to provide an assessment of the relationship among Achieving the Dream colleges, coaches and data facilitators. This brief places emphasis on the coach and data facilitator relationship to the college and how it affects the work being done related to Achieving the Dream initiative

Time for responsible peatland agriculture

Letter

Lizards and amphisbaenians (Reptilia, Squamata) from the late Eocene of Sossís (Catalonia, Spain)

A new diverse late Eocene lizard and amphisbaenian assemblage from the classical mammal locality of Sossís (Catalonia, Spain) is described. It represents the first Paleogene lizard assemblage from Spain and the first late Eocene lizard locality from the Iberian Peninsula. The family-level composition of the assemblage replicates that of other contemporaneous European localities, with the presence of iguanians, geckos, lacertids, scincids, cordyliforms, amphisbaenians, anguines, and glyptosaurines. Many of these families still occur in Catalonia, but the presence of thermophilic taxa like iguanians and cordyliforms are indicative of warmer conditions during the Eocene. The closest faunal match is with the contemporaneous French localities of the Phosphorites du Quercy. Sossís and other newly recovered Paleogene Spanish squamate assemblages have the potential to contribute to an understanding of patterns of faunal interchange between different Paleogene bioprovinces, complementing existing data on mammals

A Pillar For Successful Business School Accreditation: Conducting The Curriculum Review Process A Systematic Approach

The Association to Advance Collegiate Schools of Business (AACSB) describes their accreditation as the hallmark of business education. According to information at BestBizSchools.com (n.d.), AACSB accreditation represents the highest standard of achievement for business schools worldwide. Being AACSB accredited means a business school is able to continuously pass a strict set of standards that ensure quality. As of December 2010, only 5%, or 607, of the academic business programs globally were accredited by AACSB. This number represents schools in 38 countries where the majority of programs incorporate both undergraduate and graduate education covering business, accounting, or both. An institution must be a member of AACSB in order to apply for accreditation. It is important to note, however, that membership does not imply that the program is accredited (The Association to Advance Collegiate Schools of Business, n.d.-a). Recent emphasis demanding external validation on the quality of Business Schools has resulted in the promotion of AACSB accreditation as the de facto quality standard. Earning this quality seal of approval, business programs can verify they have met the 21 AACSB standards that cover strategic, participant, and assurance of learning achievements and processes. Programs with AACSB accreditation are encouraged to promote the standard using it to externally validate their quality and to market their programs to external groups including students, employers, and contributors (The Association to Advance Collegiate Schools of Business, n.d.-b). Despite established standards, no single approach to meeting standards for accreditation is suggested by AACSB. Rather, varying approaches to meeting standards should be developed to fit individual programs of institutions (Bryant & Scherer, 2009). This position by AACSB underscores its recognition of the diversity across accredited programs and allows educators wide latitude in developing and implementing approaches to excellence. Small programs are not disadvantaged so long as their students, faculty, graduates, and the employers who hire them receive the quality outputs that help them meet the external competitive requirements (Olian, 2007). In recognition of member institutions diversity, the AACSB has established the Affinity Group program where school administrators from schools sharing similar characteristics can interact, exchange ideas, and present views on a wide range of issues (Olian, 2007). This allows AACSB member schools, who have varying missions and constituents, to find and link with other programs of a similar nature where creativity and synergy can more easily occur. The AACSB wants the accreditation process to help facilitate creativity in designing business school strategies rather than being viewed as an impediment to a programs push to quality (Romero, 2008)