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10-on-10: The Chronicle of Evolution S.E.A. Aquarium Singapore May 23rd, 2017 John A. Long Strategic Professor in Palaeontology Flinders University, South Australia Reproduction 1) Asexual –cloning, budding Advantage –uses less energy, low risk, 100% genetic material of parent passed on Disadvantage-proliferates single genetic population 2) Sexual –by sharing genetic material Advantage-more variation in gene pool. Disadvantage- high energy, more risk, only 50% genetic material shared Shark (male) clasper The Evolution of Fish-500 million years of change From ancient simple jawless fishes (“Agnatha”) To primitive jawed forms like Placoderms To modern bony fishes (Osteichthyes) Oldest fossil fish Metaspriggina (c 520myo) No bone developed Cyclostomes- the living jawless fishes Hagfish (Eptatretus) (spawning? Not sure) Lamprey (Petromyzon) (spawning) Arthrodires Ptyctodontids Antiarchs Entelognathus (Zhu et al. Nature Sept 25, 2013) Earliest placoderms from China (425 mya) Placoderms gave us jaws and teeth (Long 2016, Science 354:280-281) GOGO 1 cm 1 cm 1 cm Micro CT scan of fossil umbilical cord Looped to placoderm embryo (Vizlab, ANU, Canberra Australia) 1 cm (Long et al. 2009, Nature) Phyllolepid arthrodires Phyllolepid sexual dimorphism (left) and copulation (right) (artwork by Peter Trusler, Monash University) Trinajstic et al. 2015 Biological Reviews 90 A serendipitous discovery in Tallinn, Estonia, late 2013 Single posterior ventrolateral plate (PVL) of Microbrachius clasper? PVL plates Geological Institute, Tallinn University of Technology (length c.2 cm) Microbrachius ‘clasper’showed similar structure to claspers of ptyctodontid placoderms Microbrachius sp, from Essi Farm, d-g, ptyctodontid Estonia (a-c) claspers from Gogo (Western Australia) Eday Flags, Middle Devonian, Orkney islands, Scotland collecting expeditions 2014, 2016 First discovery of male claspers in antiarch placoderms Male clasper development Long, J.A. et al. Nature 517 (2015) Earliest record of a female (vertebrate) Female Pterichthyodes (above) Microbrachius and Bothriolepis (right) Microbrachius female with genital plates Long, J.A. et al. Nature 517 (2015) This discovery had profound implications Internal fertilisation must have evolved several times within vertebrates (previously thought to be impossible!) Long, J.A. et al. Nature 517:196-199 (2015) Did jaws evolve for reproduction not feeding? • Shh (sonic hedgehog) signalling necessary for male clasper development and female pelvic cartilages • Androgen response element (ARE) in HAND 2 locus identified = genetic circuit for appendage development evolved an androgen regulory input, drove clasper skeletogenesis Leucoraja (skate) Males (left) female (right) Same clasper cartilages develop in females as in males but to lesser degree O’Shaughnessy et al. 2015. Nature Communications 10.1038/ncomms7698 Freitas et al PLOS One 2(8) e754 (2007) Cohn, M. (2004) Adv. Exp. Med. Biol. 545 MALE GENITAL EVOLUTION From placoderms to people The Rise of Fishes - 500 Million Dawn of the Deed – Years of Evolution The Prehistoric Origins of Sex Johns Hopkins University Press, University of Chicago Press, 2012 2011, 288 pp. PB 2014, 280pp.

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A New Antiarch Fish from the Upper Devonian Zhongning Formation of Ningxia, China
Available online at www.sciencedirect.com Palaeoworld 19 (2010) 136–145 Research paper A new antiarch fish from the Upper Devonian Zhongning Formation of Ningxia, China Lian-Tao Jia ∗, Min Zhu, Wen-Jin Zhao Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Xi Zhi Men Wai Street, 142, PO Box 643, Beijing 100044, China Received 2 April 2009; received in revised form 8 December 2009; accepted 9 February 2010 Available online 17 February 2010 Abstract A new antiarch, Ningxialepis spinosa n. gen. n. sp., is described from the Zhongning Formation (Famennian, Late Devonian) of Shixiagou, Qingtongxia, Ningxia, northwestern China. It is characterized by the presence of X-shaped pit-lines, long obstantic margins, high dorsal median spine of the trunk armour formed from the anterior and posterior median dorsal plates, prominent dorsolateral and ventrolateral ridges of the trunk armour, and the anterior median dorsal plate partly overlapping the anterior dorsolateral plate. Ningxialepis is placed as the sister taxon to Jiangxilepis in the Family Jiangxilepidae from South China, based on a phylogenetic analysis of the Euantiarcha. The Jiangxilepidae is redefined. The close affinity between Ningxialepis and Jiangxilepis further corroborates the geographic proximity between the North China and South China blocks in the Late Devonian. © 2010 Elsevier Ltd and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved. Keywords: Antiarcha; Placodermi; Late Devonian; Phylogeny; Paleogeography 1. Introduction then, abundant fish fossils (mainly antiarchs and petalichthyids) were recovered from four main Devonian Sections in Ningixa, Pan et al. (1980) first reported Devonian vertebrates in i.e., the Shixiagou and Dadaigou sections of Qingtongxia, the Ningxia, and described two antiarchs (Bothriolepis niushousha- Shanghongya Section of Zhongning, and the Hongshiwan Sec- nensis and Remigolepis zhongningensis) from the Shixiagou tion of Zhongwei (Fig.
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