CHIU, C.-H. P.*; WAGNER, G. P.*: Molecular Evolution Across the Fin-Limb Transition Evolutionary innovations in morphological characters are realized through the evolutionary modification of genes controlling the development of the characters. We follow this line of thought and examine the evolution of genes involved in the development of fins and limbs to gain insights into […]

HOGUE, A.S.*; RAVOSA, M.J.: Mandibular Symphyseal Fusion in Mammals: A Test of Competing Hypotheses The mammalian lineage is replete with instances of convergent acquisition of mandibular symphyseal fusion. While a variety of models have been proposed to explain this phenomenon, three are currently debated in the literature. Two of these, the dorsoventral (DV) shear and […]

SCHWENK, K.: Extrinsic vs. intrinsic lingual muscles: the amniote tongue as a functional unit. The muscular tongue of amniote vertebrates is traditionally described as a composite of two muscle types: extrinsic muscles originate outside the tongue and insert within it; intrinsic muscles arise and insert completely within the tongue. Whole-tongue movements are attributed to the […]

SEAVER, Elaine C; PAULSON, Dave A; IRVINE, Steve Q; MARTINDALE, Mark Q: Variation in Segment Formation in Polychaetes and its Relationship to Life History Characteristics There is a great deal of spatial and temporal variation in the way polychaetes generate their adult segmented body plan, associated primarily with changes in life history. We are interested […]

SWALLA, BJ: Origin of the Vertebrates from…….. Worms? The origin of the vertebrates has been studied intensively for over a hundred years, but recent advances in understanding developmental gene expression have allowed new ways of testing hypotheses. Urochordate and hemichordate phylogenies have shown that the deuterostomes are divided into two great clades. The chordates, including […]

SCHMIDT-OTT, U.: Evolution of Hox3 in flies The members of the evolutionarily conserved Hox-gene-complex, termed Hox genes, are required for specifying segmental identity during embryogenesis in various animal phyla. The Hox3 genes of winged insects have lost this ancestral function and are required for the development of extra-embryonic epithelia, which do not contribute to any […]

WILLIAMS, T.A.; NULSEN, C.; NAGY, L.M.: A complex role for Distal-less in the development of branched crustacean limbs The developing leg of Drosophila is initially patterned by subdivision of the leg into proximal and distal domains by the activity of the homeodomain proteins Extradenticle (Exd) and Distal-less (Dll). These early domains of gene expression are […]

NICHOLS, Scott A.; Univ. of California, Berkeley: What molecules can do that morphology cannot: Sponge systematics. Marine sponges are notorious for the extent of their conserved morphology. As a result of having few complex characters that can be used for systematics, species are frequently reported to have cosmopolitan distributions. The few data that we have […]

JAMNICZKY, Heather A.; BRINKMAN, Donald B.; RUSSELL, Anthony P.; University of Calgary, Canada; Royal Tyrrell Museum of Palaeontology, Drumheller, Canada; University of Calgary, Canada: The Utility of Cranial Arterial Canals and Foramina in the Resolution of Problems in Turtle Phylogeny Turtles have long been considered to be representative of the primitive amniote condition and have […]

BABBITT, C.C.; PATEL, N.H.; University of Chicago; University of Chicago: Phylogenetic relationships within the Malacostraca (Crustacea) based on 18S and 28S rDNA sequences The Malacostraca is the most speciose and morphologically diverse class in the Crustacea, with approximately 30,000 described species. However, because of this diversity in body plan it has been proposed that morphological […]