ABSTRACT
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, Phiomicetus anubis gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P3, and a relatively enlarged I3. Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nests Phiomicetus within the paraphyletic Protocetidae, as the most basal protocetid known from Africa. Recovery of Phiomicetus from the same bed that yielded the remingtonocetid Rayanistes afer provides the first clear evidence for the co-occurrence of the basal cetacean families Remingtonocetidae and Protocetidae in Africa. The discovery of Phiomicetus further augments our understanding of the biogeography and feeding ecology of early whales.
Subject(s)
Deer , Whales , Animals , Biological Evolution , Fossils , Phylogeny , Skull/anatomy & histologyABSTRACT
Three chamaeleon species including Chameleon Chamaeleo chamaeleon, Chameleon Chamaeleo africanus, and Chamaeleon vulgaris were collected and their tongue were dissected and examined morphologically and investigated using light and scanning electron microscopy. Both species showed similar histological manifestation of lingual papillae and tubular glands with dense mucous secretion especially in Chamaeleon vulgaris. There is no keratinization of lingual surfaces. Ultrastructurally, filliform represent the only pattern of lingual pappillae and take either cylindrical, conical and leaflet structure.Although the examined chalmaeleon species collected from different habitat, it shows almost similarities in their histological and ultrastructural structures.
Fueron recolectadas tres especies de Camaleón incluyendo Camaleón Chamaeleo chamaeleon, Camaleón Chamaeleo africanus y Chamaeleon vulgaris. Se disecó su lengua y examinó morfológicamente mediante el uso de microscopía de luz y electrónica de barrido. Ambas especies mostraron características histológicas similares en relación a las papilas linguales y glándulas tubulares con secreción mucosa densa, especialmente el Chamaeleon vulgaris. No hubo queratinización de las superficies linguales. Ultraes-tructuralmente, el único patrón de papilas linguales fue el filiforme, tomando una estructura ya sea cilíndrica, cónica y de hoja. Aunque las especies de Camaleón examinadas se recogieron de diferentes hábitat, ellas mostraron similitudes en su estructura histológica y ultraestructural.
Subject(s)
Animals , Lizards/anatomy & histology , Tongue/anatomy & histology , Microscopy, Electron, Scanning , Tongue/ultrastructureABSTRACT
Three different reptilian species Psammophis sibilans (Order Ophidia), Tarentola annularis (Order Squamata and Crocodylus niloticus (Order Crocodylia) are used in the present study. Their tongue is removed and examined morphologically. Their lingual mucosa examined under scanning electron microscopy (SEM) as well as processed for histological investigation. Gross morphological studies revealed variations of tongue gross structure being elongated with bifurcated end in P. sibilans or triangular flattened structure with broad base and conical free border in T. annularis or rough triangular fill almost the floor cavity in C. niloticus. At SEM, the lingual mucosa showed fine striated grooves radially arranged in oblique extension with missing of lingual papillae. Numerous microridges are detected above the cell surfaces in P. sibilans. T. annularis exhibited arrangement of conical flattened filiform papillae and abundant of microridges. However in C. niloticus, the lingual mucosa possessed different kinds of filiform papillae besides gustatory papillae and widespread arrangement of taste buds. Histologically, confirmed SEM of illustrating the lingual mucosa protrusion of stratified squamous epithelium in P. sibilans and presence of apical taste buds in conical filiform papillae of T. annularis. The lingual mucosa of C. niloticus revealed different forms of both filiform and gustatory papillae.
En el presente estudio fueron utilizados tres diferentes especies de reptiles Psammophis sibilans (Orden Ophidia), Tarentola annularis (Orden Squamata y Crocodylus niloticus (Orden Crocodylia). Sus lenguas fueron removidas y examinadas morfológicamente. Las mucosas linguales se examinaron bajo microscopio electrónico de barrido (SEM) y también procesadas para la investigación histológica. El estudio morfológico macroscópico reveló variaciones de la estructura de la lengua, siendo éstas alargadas con el extremo bifurcado en P. sibilans o de estructura triangular aplanada con una base amplia y el borde libre cónico en T. annularis o triangular rugosa llenando casi todo el suelo de la cavidad en C. niloticus. En el SEM, la mucosa lingual mostró finas ranuras estriadas dispuestas radialmente en la extensión oblicua con pérdida de las papilas linguales. Numerosas microcrestas fueron detectadas por encima de la superficie de las células en P. sibilans. T. annularis exhibiendo una disposición de papilas filiformes cónicas aplanadas y abundante de microcrestas. Sin embargo, en C. niloticus, la mucosa lingual posee diferentes tipos de papilas filiformes además de papilas gustativas con una extensa disposición de corpúsculos gustativas. Histológicamente, mediante confirmación de SEM se ilustra la protrusión del epitelio escamoso estratificado de la mucosa lingual en P. sibilans y la presencia de corpúsculos gustativos apicales en las papilas filiformes cónicas de T. annularis. La mucosa lingual de C. niloticus reveló diferentes formas de ambas papilas, filiformes y gustativas.
