BIOL 3300 Vertebrate Zoology: Ectotherms - Herpetology

Extant Tetrapod Phylogeny! You should be able to provide a common name for each group and describe a MAJOR feature of each clade.

Explain what is meant by… “… Reptilia and Mammalia are sister lineages among extant amniotes.” Include terms synapomorphy, plesiomorphy to describe/answer. Extant Tetrapod Phylogeny!

Figure 1.14 Linnean taxonomy places organisms in categories based on overall similarity. Evolutionary taxonomy places organisms in clades based on relatedness (homologies), which has a clear time component. A dendogram based on Linnean taxonomy (a) contains many polytomies because categories are discreet, (b) can contain some "species" (A–F and G–K) that are "equal" in rank with similar hierarchical organization to the subfamily level and others (L in particular) that contain this structure only in name, and (c) has no time component. Thus species L is in L subfamily. Dashed lines indicate where the taxonomic categories would occur for species L. A dendogram of evolutionary relationships has no clear genus, subfamily, or family structure but presents a relatively accurate hypothesis of known relationships and relative divergence times. Species are endpoints of divergences. Because of the implicit lack of a time element, individual taxonomic groups in the Linnean system often do not have comparable evolutionary histories across taxa. For example, a family of scorpions might have a much deeper (older) evolutionary history than a family of snakes.

Figure 1.15 In evolutionary taxonomy, names of evolutionary groups of organisms (clades) can be confusing. Node-based clades are defined as the most recent common ancestor (the black circle) and all descendents. For example, Anura is the most recent common ancestor of Ascaphus and Leiopelmatidae. Stem-based clades are defined as those species sharing a more recent common ancestor with a particular organism (the stem) than with another. Thus Salientia is all taxa (in this case Ascaphus and Leiopelmatidae) more closely related to Anura than to Caudata. Apomorphy-based clades share a particular unique character (the bar in the graphic on the right). Thus Anura would be the clade stemming from the first amphibian to have a urostyle (a skeletal feature unique to frogs).

What characters could you use to determine relatedness or phylogeny? Ways to determine phylogeny! Morphometric Meristic Qualitative Macroscopic Microscopic Molecular

Figure 1.16 An abbreviated cladogram of tetrapods illustrating monophyly, paraphyly, and polyphyly. The heavier lines and capitalized group names depict the monophyletic groups of Amphibia and Reptilia recognized in the text. The boxes define earlier concepts of Amphibia (polyphyletic) and Reptilia (paraphyletic). Cladistical terminology!

What are the tenets of phylogenetic systematics? 3 criteria: 1) 2) 3)

Figure 1.8 A branching diagram of the evolution within the Tetrapoda, based on sister group relationships. The diagram has no time axis, and each name represents a formal clade-group name. After Clack, 1998; Gauthier et al., 1988a,b, 1989; and Lombard and Sumida, 1992; a strikingly different pattern is suggested by Laurin and Reisz, 1997.

Figure 1.12 A branching diagram of the evolution within the Archosauromorpha, based on sister-group relationships. The diagram has no time axis; numerous clades and branching events are excluded; and each capitalized name represents a formal clade-group name. After Benton and Clark, 1988; Gauthier et al., 1989; Gower and Wilkinson, 1996.

Figure 1.13 A branching diagram of the evolution within the Lepidosauromorpha, based on sister-group relationships. The diagram has no time axis; numerous clades and branching events are excluded; and each capitalized name represents a formal clade-group name. After Gauthier et al., 1989; Rieppel, 1994; Caldwell (1996) and deBraga and Rieppel (1997) provide different interpretations of lepidosauromorph relationships.

Figure 1.4 Relationships, body forms, and limb structure of the seven key fossil vertebrates used to recover the evolution of supportive limbs in tetrapods. Glyptolepis is the outgroup. Adapted from Ahlberg and Clack, 2006; Clack 2006; Daeschler et al., 2006; and Schubin et al., 2006.

Acanthostega and Ichthyostega are more closely related to … Tetrapod Phylogeny! Tiktaalik haysvillelibrary.wordpress.com Acanthostega

Where would they fit in the cladogram? Extant Tetrapod Phylogeny!

What adaptations were necessary? – Many likely evolved while still primarily aquatic… adaptations vs. exaptations If amphibians evolved from fish… then why do we still have fish? From H 2 O to Land!

Figure 3.2 Geological occurrence of some early tetrapods, and extinct and living amphibians. Abbreviations for Cenozoic epochs: Paleo, Paleocene; Eo, Eocene; Oligo, Oligocene; Mio, Miocene; Pli, Pliocene; Pleistocene is the narrow, unlabeled epoch on the far right side of the chart. The Dicamptodontidae is now included in Ambystomatidae.

Figure 3.5 Triadobatrachus massinoti, the earliest known frog, from the Triassic of Madagascar. Adapted as a partial reconstruction from Estes and Reig, Scale bar = 1 cm. What feature(s) are “frog”; what is missing?

Figure 3.8 Vieraella herbstii, an ancient frog from the Jurassic of Patagonia. Scale bar = 2 mm. Adapted from Estes and Reig, 1973.

Figure 3.9 Paleobatrachus grandiceps, a representative of the extinct Paleobatrachidae, from the Oligocene of eastern Europe. Scale bar = 10 mm. Adapted from Estes and Reig, 1973.

Figure 3.7 Karuarus sharovi (about 15 cm TL), the earliest known salamander, from the Late Jurassic of Russia. Adapted as a partial reconstruction from Carroll, What feature(s) are “salamander”; what is missing?

Figure 3.10 Geological occurrence of some early anthracosaurs and amniotes, and extinct and living reptiles. Abbreviations for Cenozoic epochs: Paleo, Paleocene; Eo, Eocene; Oligo, Oligocene; Mio, Miocene; Pli, Pliocene; Pleistocene is the narrow, unlabeled epoch at the top of the chart. Asterisk indicates insuffficient fossil material to depict how long the taxon persisted.

Figure 3.11 Hylonomus lyelli, the earliest known reptile, from the Early Permian of Nova Scotia. Size, about 42 cm SVL. Adapted from Carroll and Baird, 1972.

Figure 3.14 Cretaceous sea showing several typical reptiles, including the turtle Protostega (left), the mosasaur Platecarpus (largest reptile), and a plesiosaur (top). The extinct bony fish Xiphactinus (bottom right) and the aquatic bird Hesperornis (center right) are also shown. By Karen Carr, with permission of the Sam Noble Oklahoma Museum of Natural History.

What is a turtle? What are Reptilia features? An ancestral turtle from the Late Triassic of southwestern China Chun Li, Xiao-Chun Wu, Olivier Rieppel, Li-Ting Wang & Li-Jun Zhao Nature 456, (27 November 2008) doi: /nature07533

Figure 3.20 Proganochelys quenstedti, the most ancient turtle, from the Lower Triassic of Germany; approximately 15 cm CL. From Gaffney, 1990; courtesy of the American Museum of Natural History.

Figure 3.23 The newly described fossil snake Najash not only has bony elements of the sacrum and hindlimbs but was also terrestrial/subterranean. Combined with other skeletal features, Najash appears to be sister to all known snakes, suggesting that snakes had a terrestrial origin rather than a marine one. Elements of the pelvis and hindlimbs are shown for Najash, Pachyrhachis, and the Boinae for comparison. Adapted from Apesteguía and Zaher, 2006

Figure 3.22 The structure of the head of the fossil snake Pachyrhachis problematicus (upper) was reconstructed using X-ray computed tomography (lower image), showing that the skull is indeed that of a basal macrostomatan snake, which means that limb loss occurred independently in different snake clades. Adapted from Polcyn et al., 2006.

Define the following terms in a sentence: OTU Clade Sister taxa Synapomorphy Type specimen (holotype, paratype, syntype) Phyly (mono, para, poly)

Why was the recently discovered fossil of the tetrapodamorph fish Tiktaalik such an important find? Why was the amniotic egg such an important innovation in the evolution of tetrapods?

Explain the difference between evolutionary taxonomy and Linnean taxonomy. Are amphibians more closely related to fishes or mammals?

Describe in detail how the transition from water to land occurred and what the major morphological preadaptations (exaptations) were that facilitated this transition. Describe the early evolution of caecilians, salamanders, frogs, turtles, and snakes… what key features tie fossils/extinct forms to extant groups?