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Current projects:

  • Systematic revision of the Eocene sharks (Chondrichthyes) from Bolca Lagerstätte, Italy (FWF-Project)
  • Evolutionary Dynamics of Eocenen Antarctic Fishes (FWF-Project)
  • Ecological effects of competition on pycnodont fishes (Actinopterygii, Neopterygii, Pycnodontomorpha) and its possible role leading to their extinction (FWF-Project)
  • Evolutionary developmental morphology of cartilaginous fishes
  • Evolutionary history of elasmobranchs (sharks, rays, and skates)
  • Elasmobranch fishes (sharks, skates, and rays) of the Adriatic Sea

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Systematic revision of the Eocene sharks (Chondrichthyes) from Bolca Lagerstätte, Italy

(FWF-Project M 2368)


Primary Investigator: Dr. Marramà, G.


Goals

The goal of the project is to review the systematics of the Eocene sharks from the Italian Bolca Lagerstätte, in order to interpret their palaeobiological, palaeoecological and biogeographic significance. Special attention will be paid to the detailed anatomical comparison with their living and extinct relatives. The Eocene (50 million years) Konservat-Lagerstätte of Bolca, in Italy, is one of the most famous palaeontological sites in the world. Although more than 100,000 fish specimens were collected from this deposit during the last four century and more than 230 taxa were erected, several aspects regarding the palaeobiodiversity and the evolutionary significance of several fish groups have been neglected or underestimated. In particular, Eocene sharks of Bolca lack of a modern perspective from a systematic and taxonomic point of view. This project will be therefore a contribution to the knowledge of one of the most famous and well-studied palaeontological sites of the world, in order to improve our understanding about the palaeoecology and palaeoenvironment of Bolca, also providing an evolutionary significance for their cartilaginous fishes, after the end-Cretaceous extinction.

Team

  • Dr. Marramà, G. (PI)
  • Univ.-Prof. Dr. Jürgen Kriwet


See here for more information Link

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Evolutionary Dynamics of Eocenen Antarctic Fishes

(FWF-Project P26465-B25)


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet


Background

The Palaeogene was one of the most important time intervals in global climatic developments characterized, inter alia, by a late Eocene transition from the greenhouse world to icehouse conditions (ca. 49-34 Ma). The final cooling phase across the Eocene-Oligocene (E-O) boundary (ca. 33.7 Ma) resulted in the thermal isolation of Antarctica and the establishment of large Antarctic ice sheets. These climatic changes, which persisted into the earliest Oligocene resulted in major biotic turnovers in marine and terrestrial floras and faunas. Today’s Southern Ocean, which is delimited by the circum-Antarctic current (Antarctic Convergence) and the Antarctic continent, which is located within it are amongst the most remote and coldest places in the world and are both a key element in any model of Earth processes and climatic changes as well as a site of unique evolutionary traits related to the abiotic characters. The extant fish fauna within the Antarctic Convergence is striking in its low taxonomic diversity and high number of endemic taxa. The chondrichthyan fauna is extremely impoverished compared to the modern teleost fauna and this situation was similar in the Eocene.
The project aims at documenting and analysing the biotic effects of both short-term and long-term climate and palaeogeographic changes in Antarctica focusing on the taxonomic composition and diversity dynamics of Eocene Antarctic holocephalan and elasmobranchian fishes, which will serve as model organisms for evolutionary patterns in high-latitudes. Analysing originations, extinctions, diversity and diversification patterns and the palaeoecology of chondrichthyans in combination with extrinsic factors, which might influence evolutionary processes (e.g., climatic changes, palaeogeographic constellations) throughout the Eocene until the thermal and geographic isolation of Antarctica will not only provide deeper insights into adaptive and evolutionary patterns of high-latitude cartilaginous fishes but also into the development and probably the origin of the conspicuous modern-day Antarctic fish fauna with no resident holocephalans and sharks. Previous hypotheses stating, for instance, that there is a continuous diversity increase until the middle Eocene and that the absence of chondrichthyans in the uppermost Eocene of Antarctica is the result of the onset of the thermal isolation of the Antarctic continent will be tested with rigorous methodological approaches.

Goals:

The ultimate goal is to present a comprehensive study of cartilaginous fish assemblages from the Eocene of Antarctica including revisions of previously published records. Integrated goals of this project are to (1) establish the taxonomic / systematic composition and stratigraphic distribution of cartilaginous fishes for each Eocene stratigraphic unit (here TELMs) of Antarctica, (2) establish the quality of their fossil record, (3) analyse the faunal relationships (Beta Diversity) of Eocene Antarctic chondrichthyan compositions, (4) study the underlying evolutionary dynamics such as origination, diversification, diversity fluctuation and extinction patterns of fishes in high latitudes during the Eocene and (5) reconstruct ecological patterns of Eocene Antarctic chondrichthyans.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI) Read more
  • Dr. Andrea Engelbrecht (Predoctoral Researcher)

Collaborations:


Available Research Projects:

Batchelor and master students (Palaeobiology, Zoology, Ecology) are welcome to conduct projects for their thesis within this project. Projects range from analytical studies employing rigorous mathematical approaches to analysing calcification patterns in skeletal elements of Antarctic fishes and taxonomic evaluations. As a Batcherlor or Masterstudent in the Vertebrate Palaeobiology Group, you will work in a very active and dynamic group on applied research projects.

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Ecological effects of competition on pycnodont fishes (Actinopterygii, Neopterygii, Pycnodontomorpha) and its possible role leading to their extinction

(FWF-Project P 29796-B29)


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet


Background

Pycnodont fishes (Pycnodontomorpha) are a monophyletic and ecologically successful clade of extinct ray finned fishes with a fossil record spanning 175 million years from the Late Triassic to middle Eocene (Tintori 1981; Poyato-Ariza & Wenz 2002; Kriwet & Schmitz 2005). They are most commonly associated with shallow water marine habitats but are also found in association with freshwater and estuarine deposits (Longbottom 1984; Poyato-Ariza et al. 1998). A deep, rounded, and laterally compressed body, a frontal flexure of the skull in profile view, a more or less prognathous snout, and elongated dorsal and anal fins, forming together with the caudal fin an effective rudder characterize pycnodonts (Fig. 1). In their body shape they superficially resemble extant coral reef fishes like butterflyfishes (Chaetodontidae), doctorfishes (Acanthuridae), and triggerfishes (Balistidae). Distinctive characteristics of pycnodonts are their molariform teeth, which generally are arranged in well-defined rows on the unpaired vomer (upper jaw) and paired prearticulars (lower jaws) (Fig. 2). This dentition represents an adaptation to shelled prey. Their diversity is strikingly high, with over >600 nominal species in >45 genera of which many taxa are based on teeth and dentitions only (Kriwet, 2001a; 2005). The palaeobiogeography of these fishes suggests they originated in the Tethys Sea initially and then spread worldwide (Kriwet 2008; Martín-Abad & Poyato-Ariza 2013).
Traditionally considered an order, Pycnodontiformes (Poyato-Ariza & Wenz 2002), they are now accepted to represent a superorder, Pycnodontomorpha, which was considered as a possible sister group candidate to Teleostei (Nursall 2010). However, a more recent analysis by Poyato-Ariza (2015) identified pycnodonts to be the sister group to Halecostomi (Holostei + Teleosteomorpha), which would make pycnodonts the most basal group among neopterygian fishes. Pycnodontomorpha comprises the orders Gyrodontiformes containing the families Gyrodontidae and Mesturidae, and Pycnodontiformes, including all remaining taxa (Nursall 2010). In this application whenever the term pycnodont is used, it refers to the total group Pycnodontomorpha.
The fact that pycnodonts weathered both the Late Triassic/Early Jurassic and the K/Pg extinction events indicates that these fishes had a particularly successful evolutionary strategy. Indeed, their increasing raw species diversity through the Mesozoic is quite plainly seen in the fossil record (Late Triassic: 4; Early Jurassic: 2; Middle Jurassic: 16; Late Jurassic: 77; Early Cretaceous: 73; Late Cretaceous: 101 [only named and currently as valid considered species listed]). The increase in raw species numbers in the Late Cretaceous is mirrored in the great increase in morphological disparity (Marramà et al. 2016a). The increase in species diversity from the Middle Jurassic onwards indicates the first diversification event in the history of pycnodonts.
A steep drop in taxon number occurred from the Late Cretaceous to Palaeocene, which might indicate that the K/P boundary event also affected pycnodont fishes. The disappearance of most major lineages well before the K/P boundary, which was used by Kriwet (2001a) to reject an extinction event at this boundary might be related to the so-called Signor-Lipps effect. Most pycnodonts known from the Palaeocene also occur in the Late Cretaceous with the exception of members of Pycnodus, which seemingly originated in the Palaeogene. This pycnodont is the most derived member of Pycnodontomorpha and the last representative of this formerly diverse group in the Eocene before it vanished, too.
A popular hypothesis regarding the extinction of pycnodonts is the observation that many modern teleost groups common in coral reefs today arose at the same time that pycnodonts were beginning to decline (Bellwood 1996; 2003). Were the pycnodonts simply outcompeted by better-adapted teleosts or could there have been other factors in their extinction?
During the Mesozoic, pycnodonts also faced competition from shallow water adapted, shell crushing ginglymodian fishes. In this case, however, the ginglymodian fishes (with the exception of Lepisosteidae) perished at the K/Pg boundary. Are there correlated evolutionary trajectories in both groups that enabled them to survive?
The project applied for here tends to answer two major questions: 1) Are competition patterns within pycnodonts and between pycnodonts, ginglymodians and ecologically similar fishes detectable, and could it explain diversity and diversification patterns within pycnodonts and 2) did the rise of teleosts, particularly Acanthomorpha, lead to the extinction of the pycnodonts in the Eocene? Thus, this project focuses on biotic rather than abiotic effects influencing diversity patterns.

Goals:

The major goals of this project are to gain deeper insights and a better understanding of the mechanisms that determine the evolutionary history, success, and final extinction of a highly diverse clade of fishes (Pycnodontomorpha). It was demonstrated that pycnodont fishes were very successful, highly diversified and evidently well adapted to the habitats they occupied. It is hypothesized that they were an important and major element of marine as well as continental influenced fish faunas (e.g., Kriwet 2001a). Nevertheless, the reasons for (1) their seemingly rapid diversification in the Early Mesozoic, (2) their subsequent success and thus their possible superiority over other fish groups inhabiting same environments (e.g., Ginglymodi), (3) their habitat use (= facies depending distribution) and possible size aggregations due to ontogenetic shifts, (4) diversity fluctuations in, i.e., relation to abiotic crises (e.g., Cenomanian/Turonian and K/P boundary events, environmental changes) or biotic factors (e.g., competition), and (5) the events triggering their final disappearance more or less simultaneously with the appearance and evolution of teleostean groups, which are considered to be important elements of modern coral-fish assemblages are ambiguous or have not been addressed with rigorous analytical methods up to now. The proposed project intends to find answers to these still not fully understood and varied aspects, which (in addition with already known traits such as feeding kinematics) will help understanding the evolutionary history of this important group and thus has the potential to identify universal evolutionary processes.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI) Read more
  • John J. Cawley, MSc (Predoctoral Researcher)
  • Fabrizio De Rossi (Student Assistant)


Available Research Projects:

Batchelor and master students (Palaeobiology, Zoology, Ecology) are welcome to conduct projects for their thesis within this project. Projects range from analytical studies employing rigorous mathematical approaches to analysing calcification patterns in skeletal elements of Antarctic fishes and taxonomic evaluations. As a Batcherlor or Masterstudent in the Vertebrate Palaeobiology Group, you will work in a very active and dynamic group on applied research projects.

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Evolutionary developmental morphology of cartilaginous fishes


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

This research area combines the traditional domain of palaeobiology with developmental morphology and developmental genetics. This project focus on the early ontogenetic development of chondrichthyan fishes, which constitute one of the two major crown groups of gnathostomes with an evolutionary history ranging back some 420 million years (probably even far more when isolated fragments are considered). The focus currently is on elasmobranch fishes (sharks, skates, rays) that become more and more model organisms for understanding the development of gnathostome traits. Here, we intend to identify phylotypic stages (= point of time when embryos of one species resemble those of others) across extant chondrichthyan clades during embryological development to provide detailed staging sequences for different clades. Timing shifts during the development of different species are well known but not yet established. These shifts in the developmental timing of organs and skeletal structures denote developmental autonomy and signify heterochronic developmental patterns. Heterochrony is a fundamental concept in macroevolutionary research. It describes time shifts of developmental events, which changed during evolution. Here, concepts and methodological approaches of morphological integration (= tendancy of different traits to vary jointly) and modularity (= modules characterized by concentration of integrated morphological traits) by employing different approaches such as Geometric Morphometrics, matrix correlations, and principal component and principal coordinate analyses but also developmental genetic approaches will be combined. This research topic thus focuses on the connection of developmental morphological trait evolution within a phylogenetic framework of cartilaginous fishes to better understand processes underlying diversification and taxonomic diversity patterns through time. The relationships between early developmental and evolutionary character transformation still also is one of the major controversies in palaeobiology since the times of E. Haeckel (1866), who proposed the recapitulation theory. Thus, we seek to better understand, how organs develop during early ontogeny and how this developmental traits relate to macroevolutionary patterns.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. C. Pfaff (Co-IP)
  • Claudia Klimpfinger (PhD student)
  • Faviel López Romero (PhD student
  • Julia Türtscher (MSc student)

Collaborations:
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Evolutionary History of Elasmobranchs (Sharks, Rays, and Skates)


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

It is obvious that the taxonomy, systematics and evolutionary topics of fossil (and even extant) elasmobranchs (sharks, rays, and skates), which represent crown chondrichthyans remain incompletely known and understood despite all progress that has been accomplished in the last decades. This is mainly due to the lack of comprehensive morphological studies of fossil specimens including teeth, cranial and postcranial characters. Generally, fossil elasmobranchs are only known from their teeth, placoid scales and isolated fin spines. In some localities, however, articulated skeletal remains largely to our knowledge of past elasmobranch anatomies and that might help, for instance, to infer character changes during their evolution. The limited data sets and inaccurate faunal descriptions continue to form a serious problem in analysing past diversity and related evolutionary patterns. Some of the problems could be corrected in the studies presented here by employing different phylogenetic methods such as cladistic principles based on parsimonious and Bayesian approaches and supertree methodologies including morphological traits and genetic marker sequences, but also statistical procedures to understand adaptive traits and disparities through time. It is also possible to infer distributional and diversity patterns from the data available and to interpret this in a non-phylogenetic framework. The fundamental goal of this research topic is to gain new and deeper insights into macroevolutionary patterns and processes of elasmobranchs such as their origin, diversity fluctuations, early evolution, mechanisms underlying evolutionary processes and novelties, and timing of diversification events. The emphasis of this research lies on post-Triassic forms, because the pre-Jurassic record of elasmobranchs comprises only a single identified group of stem-line representatives according to our current knowledge. Nevertheless, sister groups to elasmobranchs, such as the hybodontiforms and other more basal positioned taxa will be included in this research topic. Most of the research is dedicated to identifying extinct elasmobranchs taxa and characters that can be used for taxonomic and systematic purposes. This information forms the basis for drawing general patterns of their early evolution, especially during the Jurassic. The Jurassic undoubtedly represents one of the most crucial periods in the evolution of elasmobranchs when most modern clades had their first appearance in the fossil record. However, stem-group representatives such as some members of Synechodontiformes but also other Palaeozoic sharks displaying characteristic histological tooth patterns that indicate closer relationships to elasmobranchs than to other groups suggest that the total-clade Elasmobranchii originated in the Palaeozoic and underwent several phases of diversification. The ultimate objective of this project thus is to reconstruct and understand the mechanisms underlying evolutionary processes, the importance of plesiomorphic characters in the evolution of elasmobranchs, to reconstruct diversity fluctuations and analyse (adaptive) radiation events.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. Sebastian Stumpf (Co-IP)
  • Jaime Villafaña (PhD student)
  • Patrick L. Jambura (PhD student

Collaborations:
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Elasmobranch fishes (sharks, skates, and rays) of the Adriatic Sea


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

Elasmobranch (sharks, rays, and skates) populations are seriously endangered because of direct and indirect human impacts. As a consequence of intense exploitation, many species are listed in the Red List by the International Union for Conservation of Nature (IUCN) either as vulnerable or endangered. They are exceedingly vulnerable due to their low growth rates, late sexual maturi-ty and low fecundity. Nevertheless, no reliable studies are available for several parts of the Medi-terranean Sea and it currently is difficult to predict how reduction and/or loss of the top predators will modify marine ecosystems.The Adriatic Sea as part of the Mediterranean Sea is a semi-closed basin occupying the northernmost Mediterranean section. It extends from northwest to southeast for almost 800 km and has an averaged width of 200 km. The Strait of Otranto connects the sub-basin to the Ionian Sea and enables water exchange with the Mediterranean Sea. The northern Adriatic show a 35 m mean depth with a slight slope to the middle part which has an average depth of 140 m. The middle Adriatic is characterized by two depressions reaching 273 m maximum depth. The south-ern sub-basin has a steep continental slope and an abyssal plain. The south Adriatic Pit reaches 1330 m maximum depth. The Adriatic is a shallow sea and most area (around 73 %) is less than 200 m deep. It is a temperate warm sea and extremes of surface temperature range from 6 ºC to 29 ºC. Even the deepest layers are generally above 10 ºC. In winter central and northern parts are 8 to 10 ºC colder than the south Adriatic. The Adriatic basin has generally a cyclonic circulation with seasonal determining sub-basin gyres (AdriaMed, 2005). In the Adriatic Sea 28 sharks, 24 batoids and one chimaera are known as permanent resident or occasionally visiting.The Kvarner area is a part of the northern Adriatic Sea and divided into Rijeka Bay, the Kvarner Bay, Kvarnerić and the Velebit and Vinodol channels. The flat Rijeka Bay is about 60 m deep as well as the Vinodol Channel that decreases further north to a depth of under 40 m. There are narrow and elongated parts between the islands Krk to Rab and Rab to Pag which ex-ceed 100 m depth. The Krusija Channel is located between the islands Cres and Plavnik and shows the Northern Adriatic deepest point of 125 m. Most of the Kvarner area seafloor is covred by muddy and sandy sediments.The goals of this project are to (1) establish the taxonomic diversity of sharks, rays, and skates in the Kvarner bay, (2) construe the state of populations, (3) describe new discoveries, and (4) ascertain the implementation of possible conservation measurements.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Anna Schipany (MSc student)
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Evolution and Adaptation of Fishes to the Deep-Sea


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

The adaptation of fishes to deep-sea conditions is another emerging topic. Generally, it is assumed that the modern deep-sea benthic fish fauna originated in shallow waters and subsequently replaced ancient deep-sea assemblages, which became eliminated by mass extinction events. This indicates that extinction events are the main trigger for deep-sea colonization of fishes. It also is generally assumed that plesiomorphic ray-finned fish groups have more deep-sea representatives than derived ones. This study, however, is based on maximum depth occurrence data of living forms, which might be prone to error as these authors indicate. The timing and underlying processes / reasons remain ambiguous. Moreover, no definition for deep-sea fishes currently exists. Here, we intend to identify key innovations in the musculoskeletal system and to establish morphological traits for identifying deep-sea fishes. This is essential for reconstructing evolutionary traits and pathways of modern deep-sea fishes. Additionally, reliable fossil record analyses for dating such adaptive events but also diversifications in the deep will be developed and employed for providing alternative hypotheses to those currently based on molecular clocks.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. Cathrin Pfaff (Co-IP)

Collaborations:
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