DOCSLIB.ORG

The Early Diversification of Ray-Finned Fishes (Actinopterygii) a N an Ecomorphological Approach

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Early Diversification of Ray-Finned Fishes (Actinopterygii) a N an Ecomorphological Approach The early diversification ofray-finned fishes (Actinopterygii) anecomorphological approach Weronica Klasson Degree project inbiology, 2008 Examensarbete ibiologi, 20 p,2008 Biology Education Center and Department ofPhysiology and Developmental Biology Supervisor: Henning Blom The early diversification of ray-finned fishes (Actinopterygii); an ecomorphological approach Weronica Klasson Uppsala University, Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology. Examensarbete 30hp Contents Sammanfattning 2 Abstract 3 1. Introduction 4 2. Taxonomical and morphological framework 6 2.2 Shape, habitat and diet 6 2.3 Adaptation to Salt & freshwater 8 3. Environmental framework 10 3.1 Environment vs. morphology 10 3.2 Paleogeographic and paleoenvironments 11 3.3 Localities and there environments 12 3.3.1 Devonian 14 3.3.2 Carboniferous 16 4. Morphometrics analysis 19 4.1 Relative warp analysis 20 4.2 Disparity measures 21 5. Discussion 22 5.1 Ecomorphology 25 Acknowledgments 28 References 29 Appendix 1 33 List of Devonian taxa 33 List of Carboniferous taxa 34 Appendix 2 41 Relative Warp 1.1 41 Relative Warp 1.2 42 Appendix 3 43 Relative warp scores matrix 43 Relative warp scores 58 Landmarks 58 Appendix 4 64 Reconstructions of the Devonian and Carboniferous fishes 64 1 De strålfeniga fiskarnas (Actinopterygii) tidiga uppblomstring; en ekomorfologisk studie Sammanfattning Strålfeniga fiskar är idag den största och mest framgångsrika gruppen av fiskar och omfattar omkring 27000 arter, och finns i nästan alla olika typer av miljöer (habitat). Dagens mångfald är ett resultat av en rad uppblomstringar av vilka dom tidigaste verkar sammanfalla med såväl uppkomst och tidigaste utveckling under devon (416-359.2 miljoner år sedan) och karbon (359.2-299 miljoner år sedan). En morfometrisk analys (jämförande av kroppsformer) är gjord för att undersöka eventuella evolutionära mönster som kan urskiljas bland de devonska och karbonska strålfeniga fiskarnas kroppsformer (morfologier). Denna studie visar att den morfologiska mångfalden, som undersöks och kvantifierats med hjälp av olika numeriska metoder, kan jämföras med den taxonomiska mångfalden. Denna approach uppvisar en trend i vilken en jämn ökning av den morfologiska och taxonomiska mångfalden under den senare hälften av Devon, med en efterföljande mer explosionsartad ökning under tidig Karbon. Slutet av karbon uppvisar däremot en dramatisk minskning av såväl den morfologiska som taxonomiska mångfalden, en händelse som är svår att förstå och som kräver ytterligare studier. Denna studie har också visat att skillnader i kroppsform, även under dessa tidiga episoder av evolution, snarare beror på hur fiskarna levde och jagade (d.v.s. s.k. mikrohabitat) snarare än fysiska miljöfaktorer (t.ex. salinitet). Sex ”ekologiska kroppsformsgrupper” (ekomorfologiska grupper) har föreslagits och genom att jämföra dessa med motsvarande ”ekomorfologiska grupper” bland nulevande strålfeniga fiskar är det möjligt att dra mer omfattande slutsatser om hur de levde och jagade under devon och karbon. Noterbart med denna analys är att de devonska formerna hamnar i den ”ekomorfologiska grupper” som anses överraska sina byten, s.k. ”ligga och vänta predatorer” (“lay-in-wait-predators”), eller de som aktivt följer sina byten, s.k. ”följande predatorer” (“rover-predators”). Detta tyder på att de devonska formerna troligtvis var fiskätare snarare än plankton- och bryozo-ätare, vilka verkar representera en senare evolutionär utveckling. 2 The early diversification of ray-finned fishes (Actinopterygii); an ecomorphological approach Abstract The actinopterygians are the now largest and most successful group of living fishes with about 27 000 species in almost every aquatic environment. This diversity is a result of numerous radiations through time, including the origins and early diversification in the Devonian and Carboniferous. Morphometric analyses have been performed in order to investigate patterns of morphological diversity during these early episodes of actinopterygian evolution. This study shows that the disparity, which has been quantified by various methods, can be correlated to the overall taxonomic diversity. This pattern of morphological and taxonomical diversification starts with a steady increase in the Devonian, followed by what appears to be a major radiation event in the early Carboniferous. However, in the late Carboniferous both the diversity and disparity drastically decreases and the reason for this is unknown. This study also shows that there are no relation between body shape and the environments salinity. Instead it seems to be the microhabitats and the way to hunt that have the most effect on body shape. Six ecomorphological groups have been detected in the studied data set, which can give clues about feeding strategies when compared to ecomorphological groups established for recent fishes. Interestingly, the ecomorphological groupings suggest that the Devonian fishes seem to be “lay-in- wait-predators” and “rover-predators”. This means that the early ray-finned fishes probably were piscivores, rather then browsers and plankton-eaters, which seems to be a later evolutionary invention. 3 1. Introduction Eifelian and Frasnian of Scotland and Canada (Friedman and Blom 2006). The Actinopterygii, or ray-finned Cheriolepis was followed by an fishes, belong to the osteichthyans increased record of taxa in the late (bony fishes) together with the sister Devonian, probably due to the group lobe-finned fishes extension of floodplains and deltaic (Sarcopterygii). environments. The diversification then The actinopterygians are defined by speeded up in the Early Carboniferous several characters, including the (Viséan) when more ecological niches median fin rays that are inserted became available after the placoderms directly into the body, with no became extinct. Many niches also intervening basal lobe. The primitive become available when the tetrapods diamond-shaped scales, covered with went up on land and the sarcopterygian ganoine, the pelvic girdle that are decrease in the marine environments replaced with part of the (Janvier 1996). Today there are about metapterygium and soft tissue, and the 27 000 species of ray-finned fishes presence of acrodine (a transparent cap (Hurley et al. 2007). of mineralized tissue on the tip of the The phylogeny of the basic teeth) (Janvier 1996). (oldest) Actinopterygii is based on Ray-finned fishes are the different morphological characters largest and most successful group of (Figure 1), while the recent and living fishes. They are found in every younger is based on molecular data. aquatic habitat, from the high-pressure This makes it difficult to combine the depth and salinity of the ocean to living forms with the fossil record in freshwater streams and ponds, from the phylogenetic analyses. The fossil artic coldness (-1.8C) to the tropical record may involve some problems in warmth (+40C). They are also tolerant that some taxa can be “misplaced”. For to pH level from 4 to 10 and low example, two specimens of the same oxygen levels. Some can breathe air species could be put in two different and some can even cope without taxa (or the contrary two different taxa oxygen for periods of time (Moyle et put in to one) on the basis of; sexual al. 2004). There are even species that dimorphism, different size in different can crawl on land. habitat (young/adult), local The earliest record of possible morphology changes (ecological ray-finned fishes are isolated scales species can be more common then first and fragments from the Silurian, but realized) or the taphonmy (the the oldest uncontested preservation of the fossil that could actinopterygianas to be described alter the body shape) (Moyle et al. based on articulated material is 2004). Cheriolepis (Agassiz 1835) from the 4 Figure 1. Phylogenetic tree, showing the basal actinopterygians from the Devonian (bold) and Carboniferous (C. wilidi & P. decorus are Permian), based on 185 morphological characters. Also note the different environments in which the fishes lived: M = Marine F = freshwater and B = Brackish (modified from Cloutier et al. 2004). In this study the taxonomical and (2006) who explore the early morphological diversity, of several morphological diversification in the Devonian and Carboniferous coelacanth clade. actinopterygians were investigated in These types of morphometrics an environmental and temporal context methods are not mainly used on fossils to answer questions relating to the but are frequently used on recent fishes early radiation of the group. The to test various hypotheses on morphological diversity between ecomorphological questions (Costa et species have been studied to show al. 2007). A link between morphology differences in morphology depending and ecology has been shown in studies on the environment, more specifically on recent fish and Costa and if the species lived in marine water or Cataudella (2007) showed a fresh water environments have relationship between trophic ecology different body shapes. Such questions and morphology. Ruben and Adams can be referred to the concept of (2001) showed that ecology control the ecomorphology, which can be defined morphology more than the genes, as, “a study of the relationship between which means that the plasticity of the the ecological role of an individual and fish was more than first expected. The its morphological adaptations” morphology of a species is then shaped (Rickleffs 1990). One way to study
Load more

Recommended publications
  • Table S1.Xlsx
    Bone type Bone type Taxonomy Order/series Family Valid binomial Outdated binomial Notes Reference(s) (skeletal bone) (scales) Actinopterygii Incertae sedis Incertae sedis Incertae sedis †Birgeria stensioei cellular this study †Birgeria groenlandica cellular Ørvig, 1978 †Eurynotus crenatus cellular Goodrich, 1907; Schultze, 2016 †Mimipiscis toombsi †Mimia toombsi cellular Richter & Smith, 1995 †Moythomasia sp. cellular cellular Sire et al., 2009; Schultze, 2016 †Cheirolepidiformes †Cheirolepididae †Cheirolepis canadensis cellular cellular Goodrich, 1907; Sire et al., 2009; Zylberberg et al., 2016; Meunier et al. 2018a; this study Cladistia Polypteriformes Polypteridae †Bawitius sp. cellular Meunier et al., 2016 †Dajetella sudamericana cellular cellular Gayet & Meunier, 1992 Erpetoichthys calabaricus Calamoichthys sp. cellular Moss, 1961a; this study †Pollia suarezi cellular cellular Meunier & Gayet, 1996 Polypterus bichir cellular cellular Kölliker, 1859; Stéphan, 1900; Goodrich, 1907; Ørvig, 1978 Polypterus delhezi cellular this study Polypterus ornatipinnis cellular Totland et al., 2011 Polypterus senegalus cellular Sire et al., 2009 Polypterus sp. cellular Moss, 1961a †Scanilepis sp. cellular Sire et al., 2009 †Scanilepis dubia cellular cellular Ørvig, 1978 †Saurichthyiformes †Saurichthyidae †Saurichthys sp. cellular Scheyer et al., 2014 Chondrostei †Chondrosteiformes †Chondrosteidae †Chondrosteus acipenseroides cellular this study Acipenseriformes Acipenseridae Acipenser baerii cellular Leprévost et al., 2017 Acipenser gueldenstaedtii
    [Show full text]
  • A Late Permian Ichthyofauna from the Zechstein Basin, Lithuania-Latvia Region
    bioRxiv preprint doi: https://doi.org/10.1101/554998; this version posted February 20, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 A late Permian ichthyofauna from the Zechstein Basin, Lithuania-Latvia Region 2 3 Darja Dankina-Beyer1*, Andrej Spiridonov1,4, Ģirts Stinkulis2, Esther Manzanares3, 4 Sigitas Radzevičius1 5 6 1 Department of Geology and Mineralogy, Vilnius University, Vilnius, Lithuania 7 2 Chairman of Bedrock Geology, Faculty of Geography and Earth Sciences, University 8 of Latvia, Riga, Latvia 9 3 Department of Botany and Geology, University of Valencia, Valencia, Spain 10 4 Laboratory of Bedrock Geology, Nature Research Centre, Vilnius, Lithuania 11 12 *[email protected] (DD-B) 13 14 Abstract 15 The late Permian is a transformative time, which ended in one of the most 16 significant extinction events in Earth’s history. Fish assemblages are a major 17 component of marine foods webs. The macroevolution and biogeographic patterns of 18 late Permian fish are currently insufficiently known. In this contribution, the late Permian 19 fish fauna from Kūmas quarry (southern Latvia) is described for the first time. As a 20 result, the studied late Permian Latvian assemblage consisted of isolated 21 chondrichthyan teeth of Helodus sp., ?Acrodus sp., ?Omanoselache sp. and 22 euselachian type dermal denticles as well as many osteichthyan scales of the 23 Haplolepidae and Elonichthydae; numerous teeth of Palaeoniscus, rare teeth findings of 1 bioRxiv preprint doi: https://doi.org/10.1101/554998; this version posted February 20, 2019.
    [Show full text]
  • A New Osteolepidid Fish From
    Rea. West. Aust. MU8. 1985, 12(3): 361-377 ANew Osteolepidid Fish from the Upper Devonian Gogo Formation, Western Australia J.A. Long* Abstract A new osteolepidid crossopterygian, Gogonasus andrewsi gen. et sp. nov., is des­ cribed from a single fronto-ethmoidal shield and associated ethmosphenoid, from the Late Devonian (Frasnian) Gogo Formation, Western Australia. Gogonasus is is distinguished from other osteolepids by the shape and proportions of the fronto­ ethmoidal shield, absence of palatal fenestrae, well developed basipterygoid pro­ cesses and moderately broad parasphenoid. The family Osteolepididae is found to be paraphyletic, with Gogonasus being regarded as a plesiomorphic osteolepidid at a similar level of organisation to Thursius. Introduction Much has been published on the well-preserved Late Devonian fish fauna from the Gogo Formation, Western Australia, although to date all the papers describing fish have been on placoderms (Miles 1971; Miles and Dennis 1979; Dennis and Miles 1979-1983; Young 1984), palaeoniscoids (Gardiner 1973, 1984; Gardiner and Bartram 1977) or dipnoans (Miles 1977; Campbell and Barwick 1982a, 1982b, 1983, 1984a). This paper describes the only osteolepiform from the fauna (Gardiner and Miles 1975), a small snout with associated braincase, ANU 21885, housed in the Geology Department, Australian National University. The specimen, collected by the Australian National University on the 1967 Gogo Expedition, was prepared by Dr S.M. Andrews (Royal Scottish Museum) and later returned to the ANU. Onychodus is the only other crossopterygian in the fauna. In its proportions and palatal structure the new specimen provides some additional new points of the anatomy of osteolepiforms. Few Devonian crossopte­ rygians are known from Australia, and so the specimen is significant in having resemblances to typical Northern Hemisphere species.
    [Show full text]
  • Striped Bass
    Can you tell the difference between a striped bass, a white bass and a striped bass hybrid? Anglers need to know the differences between these spe- cies because different sizes, seasons and creel limits apply to striped bass and striped bass hybrids, and to white bass. Knowing the differences between these species can also help you better understand Pennsylvania fishes and our wa- ters. These fish belong to the family Moronidae, temperate basses, also known as “true” basses. In Pennsylvania, this family also includes the white perch. Moronidae species are medium-sized to large-sized active predators and prized trophy and sport fishes. Some species live only in fresh water, while others are anadromous they spend much of their lives in salt water or brackish water but return to fresh water to spawn. Striped Bass Morone saxatilis Identification: The striped bass has a smoothly arched pro- file, slimmer and more streamlined than a striped bass hybrid, until it reaches a weight of five to 10 pounds, when its body becomes heavy-looking. The back is olive-green to steely blue- gray, sometimes almost black. The sides are silvery to pale rapidly and stay in brackish bays at the end of their downstream silvery-green, shading to white on the belly. There are seven float. Juveniles spend their first and second summers in the or eight distinct dark stripes that run laterally on the side of tidal Delaware River with most inhabitating that area from the the body. Striped bass have two dorsal fins, the front spiny- Schuylkill River downstream into the state of Delaware.
    [Show full text]
  • Genetic Analysis of Whole Mitochondrial Genome of Lateolabrax Maculatus (Perciformes: Moronidae) Indicates the Presence of Two Populations Along the Chinese Coast
    ZOOLOGIA 37: e49046 ISSN 1984-4689 (online) zoologia.pensoft.net RESEARCH ARTICLE Genetic analysis of whole mitochondrial genome of Lateolabrax maculatus (Perciformes: Moronidae) indicates the presence of two populations along the Chinese coast Jie Gong 1,2, Baohua Chen 1,2, Bijun Li 1, Zhixiong Zhou 1, Yue Shi 1, Qiaozhen Ke 1,3, Dianchang Zhang 4, Peng Xu 1,2,3 1Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, Xiamen University. 361000 Xiamen, China. 2Shenzhen Research Institute, Xiamen University. 518000 Shenzhen, China. 3State Key Laboratory of Large Yellow Croaker Breeding, Ningde Fufa Fisheries Company Limited. 352130 Ningde, China. 4South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences. 510300 Guangzhou, China. Corresponding author: Peng Xu ([email protected]) http://zoobank.org/B5BBA46C-7FC5-44C3-B9CE-19F8E93FAA1C ABSTRACT. The whole mitochondrial genome of Lateolabrax maculatus (Cuvier, 1828) was used to investigate the reasons for the observed patterns of genetic differentiation among 12 populations in northern and southern China. The haplotype diversity and nucleotide diversity of L. maculatus were 0.998 and 0.00169, respectively. Pairwise FST values between popula- tions ranged from 0.001 to 0.429, correlating positively with geographic distance. Genetic structure analysis and haplotype network analysis indicated that these populations were split into two groups, in agreement with geographic segregation and environment. Tajima’s D values, Fu’s Fs tests and Bayesian skyline plot (BSP) indicated that a demographic expansion event may have occurred in the history of L. maculatus. Through selection pressure analysis, we found evidence of significant negative selection at the ATP6, ND3, Cytb, COX3, COX2 and COX1 genes.
    [Show full text]
  • First Record of F2 Hybrid Striped Bass (Morone Chrysops ♀ × Morone Saxatilis ♂ × Morone Chrysops ♀ × Morone Saxatilis ♂) in Kemer Dam Lake
    Turkish Journal of Zoology Turk J Zool (2014) 38: 637-641 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1304-42 First record of F2 hybrid striped bass (Morone chrysops ♀ × Morone saxatilis ♂ × Morone chrysops ♀ × Morone saxatilis ♂) in Kemer Dam Lake 1, 2 Volkan KIZAK *, Yusuf GÜNER 1 Fisheries Faculty, Tunceli University, Tunceli, Turkey 2 Fisheries Faculty, Ege University, İzmir, Turkey Received: 26.04.2013 Accepted: 19.03.2014 Published Online: 14.07.2014 Printed: 13.08.2014 Abstract: The morphometric and meristic characters of 2 F2 hybrid striped bass (M. chrysops ♀ × M. saxatilis ♂ × M. chrysops ♀ × M. saxatilis ♂) from the family Moronidae are described. Two specimens were caught from Kemer Dam Lake. The body of the F2 hybrid striped bass was elongated, moderately compressed, and scaly. Dorsal surface and sides were silver and black to olive-gray, and the abdomen was white in color. Four or 5 longitudinal broken stripes ran above the lateral line to the caudal fin. The stripes were less visible behind the pectoral fins and below the lateral line. The bodies of the2 F specimens were deeper than 1/4 the fork length. The 2 dorsal fins were separated entirely. The first dorsal fin had 8–9 spines, and the second dorsal fin had a spine and 13–14 soft rays. The caudal fin was slightly forked. The anal fin had 3 spines with 12–14 soft rays. One tooth patch was present on the anterior of the tongue. According to our results, the fish were 2F hybrid striped bass offspring of 1F hybrid striped bass, which can reproduce naturally in Turkey.
    [Show full text]
  • 'Placoderm' (Arthrodira)
    Jobbins et al. Swiss J Palaeontol (2021) 140:2 https://doi.org/10.1186/s13358-020-00212-w Swiss Journal of Palaeontology RESEARCH ARTICLE Open Access A large Middle Devonian eubrachythoracid ‘placoderm’ (Arthrodira) jaw from northern Gondwana Melina Jobbins1* , Martin Rücklin2, Thodoris Argyriou3 and Christian Klug1 Abstract For the understanding of the evolution of jawed vertebrates and jaws and teeth, ‘placoderms’ are crucial as they exhibit an impressive morphological disparity associated with the early stages of this process. The Devonian of Morocco is famous for its rich occurrences of arthrodire ‘placoderms’. While Late Devonian strata are rich in arthrodire remains, they are less common in older strata. Here, we describe a large tooth-bearing jaw element of Leptodontich- thys ziregensis gen. et sp. nov., an eubrachythoracid arthrodire from the Middle Devonian of Morocco. This species is based on a large posterior superognathal with a strong dentition. The jawbone displays features considered syna- pomorphies of Late Devonian eubrachythoracid arthrodires, with one posterior and one lateral row of conical teeth oriented postero-lingually. μCT-images reveal internal structures including pulp cavities and dentinous tissues. The posterior orientation of the teeth and the traces of a putative occlusal contact on the lingual side of the bone imply that these teeth were hardly used for feeding. Similar to Compagopiscis and Plourdosteus, functional teeth were pos- sibly present during an earlier developmental stage and have been worn entirely. The morphological features of the jaw element suggest a close relationship with plourdosteids. Its size implies that the animal was rather large. Keywords: Arthrodira, Dentition, Food web, Givetian, Maïder basin, Palaeoecology Introduction important to reconstruct character evolution in early ‘Placoderms’ are considered as a paraphyletic grade vertebrates.
    [Show full text]
  • Geological Survey of Ohio
    GEOLOGICAL SURVEY OF OHIO. VOL. I.—PART II. PALÆONTOLOGY. SECTION II. DESCRIPTIONS OF FOSSIL FISHES. BY J. S. NEWBERRY. Digital version copyrighted ©2012 by Don Chesnut. THE CLASSIFICATION AND GEOLOGICAL DISTRIBUTION OF OUR FOSSIL FISHES. So little is generally known in regard to American fossil fishes, that I have thought the notes which I now give upon some of them would be more interesting and intelligible if those into whose hands they will fall could have a more comprehensive view of this branch of palæontology than they afford. I shall therefore preface the descriptions which follow with a few words on the geological distribution of our Palæozoic fishes, and on the relations which they sustain to fossil forms found in other countries, and to living fishes. This seems the more necessary, as no summary of what is known of our fossil fishes has ever been given, and the literature of the subject is so scattered through scientific journals and the proceedings of learned societies, as to be practically inaccessible to most of those who will be readers of this report. I. THE ZOOLOGICAL RELATIONS OF OUR FOSSIL FISHES. To the common observer, the class of Fishes seems to be well defined and quite distin ct from all the other groups o f vertebrate animals; but the comparative anatomist finds in certain unusual and aberrant forms peculiarities of structure which link the Fishes to the Invertebrates below and Amphibians above, in such a way as to render it difficult, if not impossible, to draw the lines sharply between these great groups.
    [Show full text]
  • Osteichthyes, Actinopterygii) from the Early Triassic of Northwestern Madagascar
    Rivista Italiana di Paleontologia e Stratigrafia (Research in Paleontology and Stratigraphy) vol. 123(2): 219-242. July 2017 REDESCRIPTION OF ‘PERLEIDUS’ (OSTEICHTHYES, ACTINOPTERYGII) FROM THE EARLY TRIASSIC OF NORTHWESTERN MADAGASCAR GIUSEPPE MARRAMÀ1*, CRISTINA LOMBARDO2, ANDREA TINTORI2 & GIORGIO CARNEVALE3 1*Corresponding author. Department of Paleontology, University of Vienna, Geozentrum, Althanstrasse 14, 1090 Vienna, Austria. E-mail: [email protected] 2Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli 34, I-20133 Milano, Italy. E-mail: cristina.lombardo@ unimi.it; [email protected] 3Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy. E-mail: giorgio.carnevale@ unito.it To cite this article: Marramà G., Lombardo C., Tintori A. & Carnevale G. (2017) - Redescription of ‘Perleidus’ (Osteichthyes, Actinopterygii) from the Early Triassic of northwestern Madagascar . Riv. It. Paleontol. Strat., 123(2): 219-242. Keywords: Teffichthys gen. n.; TEFF; Ankitokazo basin; geometric morphometrics; intraspecific variation; basal actinopterygians. Abstract. The revision of the material from the Lower Triassic fossil-bearing-nodule levels from northwe- stern Madagascar supports the assumption that the genus Perleidus De Alessandri, 1910 is not present in the Early Triassic. In the past, the presence of this genus has been reported in the Early Triassic of Angola, Canada, China, Greenland, Madagascar and Spitsbergen. More recently, it has been pointed out that these taxa may not be ascri- bed to Perleidus owing to several anatomical differences. The morphometric, meristic and morphological analyses revealed a remarkable ontogenetic and individual intraspecific variation among dozens of specimens from the lower Triassic of Ankitokazo basin, northwestern Madagascar and allowed to consider the two Malagasyan species P.
    [Show full text]
  • Ecca Group) of South Africa: a Preliminary Review of Palaeoniscoid Fishes and Taphonomy
    Records of the Western Australian Museum Supplement No. 57: 175-181 (1999). The Permian Whitehill Formation (Ecca Group) of South Africa: a preliminary review of palaeoniscoid fishes and taphonomy Fiona J. Evans 1 and Patrick A. Bender2 I Department of Zoology, University of Stellenbosch, Private Bag Xl, Matieland, 7602, South Africa; email: [email protected] 2 Museum of the Council for Geoscience, Private Bag Xl12, Pretoria, 0001, South Africa Abstract - The Permian (Artinskian) Whitehill Formation (Ecca Group) in South Africa and southern Namibia was deposited as part of a large stratified inland sea which extended from the southern margins of South Africa, and southern Namibia, northern Namibia (Aba-Huab Formation, Huab Basin) to the Iratl Formation of the Parana Basin in Brazil and parts of Uruguay. A common biota exists between these two continents, namely mesosaurid reptiles, pygocephalomorph crustacea, wood, palaeoniscoid fish and insects. The Whitehill Formation also contains plant stem fragments, palynomorphs, coprolites, a cephalochordate, rare sponge spicules and traces of arthropods and fish. The good preservation, particularly of the palaeoniscoid material, from the Whitehill Formation contrasts strongly with the disarticulated scales and spines from northern Namibia and Brazil. Recent collections in the Whitehill Formation near Calvinia and Louriesfontein (Northern Cape Province) of South Africa have demonstrated the necessity for a review of the palaeoniscoid taxa present in these units. Possible new species have also been collected, including a deep-bodied form. INTRODUCTION The extensive stratified inland sea in which the Whitehill Formation (Ecca Group, Karoo Supergroup; - - - - - Waterford Fm Figure 1) was deposited had limited or no access to ------------ the ocean according to reconstructions by Oelofsen Fort Brown Fm and Araujo (1987) and Pickford (1995).
    [Show full text]
  • Coincidence of Photic Zone Euxinia and Impoverishment of Arthropods
    www.nature.com/scientificreports OPEN Coincidence of photic zone euxinia and impoverishment of arthropods in the aftermath of the Frasnian- Famennian biotic crisis Krzysztof Broda1*, Leszek Marynowski2, Michał Rakociński1 & Michał Zatoń1 The lowermost Famennian deposits of the Kowala quarry (Holy Cross Mountains, Poland) are becoming famous for their rich fossil content such as their abundant phosphatized arthropod remains (mostly thylacocephalans). Here, for the frst time, palaeontological and geochemical data were integrated to document abundance and diversity patterns in the context of palaeoenvironmental changes. During deposition, the generally oxic to suboxic conditions were interrupted at least twice by the onset of photic zone euxinia (PZE). Previously, PZE was considered as essential in preserving phosphatised fossils from, e.g., the famous Gogo Formation, Australia. Here, we show, however, that during PZE, the abundance of arthropods drastically dropped. The phosphorous content during PZE was also very low in comparison to that from oxic-suboxic intervals where arthropods are the most abundant. As phosphorous is essential for phosphatisation but also tends to fux of the sediment during bottom water anoxia, we propose that the PZE in such a case does not promote the fossilisation of the arthropods but instead leads to their impoverishment and non-preservation. Thus, the PZE conditions with anoxic bottom waters cannot be presumed as universal for exceptional fossil preservation by phosphatisation, and caution must be paid when interpreting the fossil abundance on the background of redox conditions. 1 Euxinic conditions in aquatic environments are defned as the presence of H2S and absence of oxygen . If such conditions occur at the chemocline in the water column, where light is available, they are defned as photic zone euxinia (PZE).
    [Show full text]
  • Copyrighted Material
    06_250317 part1-3.qxd 12/13/05 7:32 PM Page 15 Phylum Chordata Chordates are placed in the superphylum Deuterostomia. The possible rela- tionships of the chordates and deuterostomes to other metazoans are dis- cussed in Halanych (2004). He restricts the taxon of deuterostomes to the chordates and their proposed immediate sister group, a taxon comprising the hemichordates, echinoderms, and the wormlike Xenoturbella. The phylum Chordata has been used by most recent workers to encompass members of the subphyla Urochordata (tunicates or sea-squirts), Cephalochordata (lancelets), and Craniata (fishes, amphibians, reptiles, birds, and mammals). The Cephalochordata and Craniata form a mono- phyletic group (e.g., Cameron et al., 2000; Halanych, 2004). Much disagree- ment exists concerning the interrelationships and classification of the Chordata, and the inclusion of the urochordates as sister to the cephalochor- dates and craniates is not as broadly held as the sister-group relationship of cephalochordates and craniates (Halanych, 2004). Many excitingCOPYRIGHTED fossil finds in recent years MATERIAL reveal what the first fishes may have looked like, and these finds push the fossil record of fishes back into the early Cambrian, far further back than previously known. There is still much difference of opinion on the phylogenetic position of these new Cambrian species, and many new discoveries and changes in early fish systematics may be expected over the next decade. As noted by Halanych (2004), D.-G. (D.) Shu and collaborators have discovered fossil ascidians (e.g., Cheungkongella), cephalochordate-like yunnanozoans (Haikouella and Yunnanozoon), and jaw- less craniates (Myllokunmingia, and its junior synonym Haikouichthys) over the 15 06_250317 part1-3.qxd 12/13/05 7:32 PM Page 16 16 Fishes of the World last few years that push the origins of these three major taxa at least into the Lower Cambrian (approximately 530–540 million years ago).
    [Show full text]