First shark from the late Devonian (Frasnian) gogo formation, Western Australia sheds new light on the development of tessellated calcified cartilage

Background: Living gnathostomes (jawed vertebrates) comprise two divisions, Chondrichthyes (cartilaginous fishes, including euchondrichthyans with prismatic calcified cartilage, and extinct stem chondrichthyans) and Osteichthyes (bony fishes including tetrapods). Most of the early chondrichthyan (‘shark’) record is based upon isolated teeth, spines, and scales, with the oldest articulated sharks that exhibit major diagnostic characters of the group—prismatic calcified cartilage and pelvic claspers in males—being from the latest Devonian, c. 360 Mya. This paucity of information about early chondrichthyan anatomy is mainly due to their lack of endoskeletal bone and consequent low preservation potential. Methodology/Principal Findings: Here we present new data from the first well-preserved chondrichthyan fossil from the early Late Devonian (ca. 380–384 Mya) Gogo Formation Lägerstatte of Western Australia. The specimen is the first Devonian shark body fossil to be acid-prepared, revealing the endoskeletal elements as three-dimensional undistorted units: Meckel’s cartilages, nasal, ceratohyal, basibranchial and possible epibranchial cartilages, plus left and right scapulocoracoids, as well as teeth and scales. This unique specimen is assigned to Gogoselachus lynnbeazleyae n. gen. n. sp.Conclusions/Significance: The Meckel’s cartilages show a jaw articulation surface dominated by an expansive cotylus, and a small mandibular knob, an unusual condition for chondrichthyans. The scapulocoracoid of the new specimen shows evidence of two pectoral fin basal articulation facets, differing from the standard condition for early gnathostomes which have either one or three articulations. The tooth structure is intermediate between the ‘primitive’ ctenacanthiform and symmoriiform condition, and more derived forms with a euselachian-type base. Of special interest is the highly distinctive type of calcified cartilage forming the endoskeleton, comprising multiple layers of nonprismatic subpolygonal tesserae separated by a cellular matrix, interpreted as a transitional step toward the tessellated prismatic calcified cartilage that is recognized as the main diagnostic character of the chondrichthyans

Transcending disciplines: Engaging college students in interdisciplinary research, integrated STEM, and partnerships

An authentic, interdisciplinary, research and problem-based integrated science, technology, engineering, and mathematics (STEM) project may be ideal for encouraging scientific inquiry and developing teamwork among undergraduate students, but it also presents challenges. The authors describe how two interdisciplinary teams (n=6) of undergraduate college students built integrated STEM projects in a research based internship setting, and then collaboratively brought the project to fruition to include designing lessons and activities shared with K-12 students in a classroom setting. Each three person undergraduate team consisted of two STEM majors and one Education major. The Education majors are a special focus for this study. Interviews, field observations, and lesson plan artifacts collected from the undergraduate college students were analyzed according to authenticity factors, the authentic scientific inquiry instrument, and an integrated STEM instrument. The authors highlight areas of strength and weakness for both teams and explore how preservice teachers contributed to integrated STEM products and lessons. Teacher educators might apply recommendations for teacher preparation and professional development when facilitating authentic scientific inquiry and integrated STEM topics with both STEM and non-STEM educators. Undergraduate college students were challenged to fully integrate the STEM disciplines, transitions between them, and the spaces between them where multiple disciplines existed. By describing the challenges of integrating the spaces between STEM, the authors offer a description of the undergraduate college students’ experiences in an effort to expand the common message beyond a flat approach of try this activity because it works, to a more robust message of try this type of engagement and purposefully organize for maximum results