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The nowadays hyper-diverse clade of Actinopterygii (ray-finned bony fishes) is characterized by a long evolutionary history and an extremely rich global fossil record. This work builds upon 170 years of research on the fossil record of this clade in Greece. The taxonomy and spatiotemporal distribution of the ray-finned fish record of Greece are critically revisited and placed in an updated systematic and stratigraphic framework, while some new fossil data and interpretations are also provided. Greece hosts diverse ray-finned fish assemblages, which range in age from Lower Jurassic to Quaternary. Most known assemblages are of Miocene–Pliocene age and of marine affinities. A minimum of 32 families, followed by at least 34 genera and 22 species, have been recognized in Greece. From originally two named genera and seven species, only two fossil species, established on Greek material, are accepted as valid. Additional taxonomic diversity is anticipated, pending detailed investigations. From a taxonomic perspective, previous knowledge lies on preliminary or authoritative assessments of fossils, with many decades-old treatments needing revision. Little is known about Mesozoic–early Cenozoic occurrences or freshwater assemblages. Given the proven potential of the Greek fossil record, this chapter stresses the need for additional exploration and the establishment of permanent, curated collections of fossil fishes in Greek institutions. Directions for future research are discussed.

The fossil record of marine ray-finned fishes (Actinopterygii) from the time interval surrounding the Cretaceous–Paleogene (K–Pg) extinction is scarce at a global scale, hampering our understanding of the impact, patterns and processes of extinction and recovery in the marine realm, and its role in the evolution of modern marine ichthyofaunas. Recent fieldwork in the K–Pg interval of the Pindos Unit in Eurytania, continental Greece, shed new light on forgotten fossil assemblages and allowed for the collection of a diverse, but fragmentary sample of actinopterygians from both late Maastrichtian and Paleocene rocks. Late Maastrichtian assemblages are dominated by Aulopiformes (†Ichthyotringidae, †Enchodontidae), while †Dercetidae (also Aulopiformes), elopomorphs and additional, unidentified teleosts form minor components. Paleocene fossils include a clupeid, a stomiiform and some unidentified teleost remains. This study expands the poor record of body fossils from this critical time interval, especially for smaller sized taxa, while providing a rare, paleogeographically constrained, qualitative glimpse of open-water Tethyan ecosystems from both before and after the extinction event. Faunal similarities between the Maastrichtian of Eurytania and older Late Cretaceous faunas reveal a higher taxonomic continuum in offshore actinopterygian faunas and ecosystems spanning the entire Late Cretaceous of the Tethys. At the same time, the scarcity of Paleocene findings offers tentative clues for a depauperate state of Tethyan ichthyofaunas in the aftermath of the K–Pg Extinction.

The actinopterygian crown group (comprising all living ray-finned fishes) originated by the end of the Carboniferous. However, most late Paleozoic taxa are stem actinopterygians, and broadly resemble stratigraphically older taxa. The early Permian †

Viviparity has evolved independently at least 12 times in ray-finned fishes. However, the fossil record of actinopterygian viviparity is poor, with only two documented occurrences. Both of these are from the non-teleost actinopterygian Saurichthys, and include S. curionii and S. macrocephalus from the Middle Triassic Meride Limestone (Monte San Giorgio, Switzerland). Here, we present new data on the reproductive biology of these species, giving unprecedented insights into their life-history. Based on positional and preservational criteria, six specimens were identified as unambiguously gravid. Embryos were positioned dorsal to the gastrointestinal tract, parallel to the axial skeleton and to each other, in the posterior two-thirds of the abdominal region. A minimum of 16 embryos are preserved in the most fecund females and, based on the largest preserved embryos and smallest preserved neonates, birth must have occurred at 7–12% of maternal fork length. Embryonic crania and teeth are relatively well-ossified, however ossification of the parietal region is delayed. In the postcranium, the median scale rows and lepidotrichia are ossified, but not the lateral scale rows. Ossified squamation and gradual allometric growth suggests that neonates did not undergo metamorphosis and were relatively precocial. When considered in a phylogenetic context, neither live birth nor internal fertilization appears to represent the primitive state for saurichthyid fishes. Key words: Actinopterygii, Saurichthys, Triassic, Monte San Giorgio, viviparity, allometry

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List of new and modified characters and scoring changes. (PDF 46 kb)

Recent excavations and prospecting in the early to middle Miocene deposits of the Maradah Formation in Jabal Zaltan, Libya, yielded a diverse fish assemblage coming from an early Miocene locality. The material described here includes more than 18 marine and freshwater taxa most of which were previously unreported from the area. Jabal Zaltan is one of the very few early Miocene Afroarabian fossil sites that produced such a diverse fish sample. Therefore, the fossils described here provide a unique insight into the composition of the early Miocene fish faunas from the northern African coast; a critical time period for faunas of the continent, as contact with Eurasia ended 100 million years of African isolation. In addition, the Jabal Zaltan fossils help consolidate the validity of Galeocerdo mayumbensis and extend its geographic range to include the Tethys. The Maradah deposits also host the first occurrences of two genera (Pteromylaeus, Distichodus) in the fossil record. The fish finds support the presumed depositional environment that of tropical shallow estuarine to deltaic conditions, and the freshwater fishes document the presence of a modern-type Nilosudanian fauna containing elements with both African and Asian affinities. The Jabal Zaltan ichthyofauna, with its diversity of taxa, has the potential to become a key reference fauna for future studies of early Miocene African fishes.

The Fayum Depression of Egypt has produced a great diversity of fossil material, including marine and freshwater fishes. In contrast to the Eocene formations of the Fayum, the Oligocene Jbel Qatrani Formation has been more or less consistently considered to be deposited in a freshwater environment; however, the ichthyofauna indicates a more complex picture. Cenozoic fishes have been convincingly used to interpret the palaeoenvironment in which sediments were deposited. Based on the elasmobranch and osteichthyan faunas of the Jbel Qatrani Formation, we interpret that this formation was not deposited entirely in fresh waters, but had some marine influence, particularly in the lower part of the formation. The mixture of freshwater elements, such as polypterids and alestids, with brackish and marine elements, including myliobatid stingrays, in the Quarry E site suggests a local palaeoenvironment that was very close to the shoreline, in a less protected area, or under more seasonal influence than the rest of the sites in the formation. Additionally, the early Oligocene elasmobranch fishes from Quarry E have a strong biogeographic relationship with sites in Oman and Pakistan, in the eastern Tethys, representing a restricted fauna possibly limited in distribution by cooling global temperatures.

Disarticulated fossil remains of a same indeterminate perciform have been described in Neogene deposits from Africa, in Libya (Upper Miocene of Sahabi) and in Namibia (Middle Miocene of Arrisdrift), and then from Germany (Lower Miocene of Langenau). Found in association with strictly or dominantly freshwater faunas, they were supposed to be freshwater fish. However, their distribution was rather difficult to interpret and their comparison with freshwater ichthyotaxa did not permit to attribute them neither to a known genus even nor to a known family. By comparison with marine perciforms, the review of the African fossils allowed us to attribute them to the genus Argyrosomus (Teleostei, Sciaenidae) or “Meagre”. Only new fossil material and an acute study of the osteology of extant species might allow specific attribution of this bony material. These African fossils and those from Langenau constitute the whole bony fossil record of the genus Argyrosomus De La Pylaie, 1835 that is also known by otol...

The Permian deposits of Hydra Island, Greece, have been known for over a century and host some of the best-studied and most diverse invertebrate assemblages of the ancient Paleotethys Ocean. However, until now, no Paleozoic fossils of jawed vertebrates had been reported from Greece. Recent fieldwork on Hydra Island brought to light rare cartilaginous fish remains, including a tooth belonging to an unknown hybodontiform shark, as well as an unidentifiable dermal denticle of an euselachian shark. Despite similarities with iconic Paleozoic and Mesozoic durophagous euselachians, the Hydriot tooth likely corresponds to a new species, but is provisionally left in open nomenclature until more material becomes available. The new chondrichthyan fossils from Hydra Island correspond to one of the few Lopingian (late Permian) occurrences known from the Paleotethys. Moreover, they constitute the oldest record of jawed-vertebrate fossils from Greece, predating younger occurrences by more than 50 million years.

Renewed research at the early Miocene fossil site of Bukwa in northeastern Uganda has resulted in new fossil finds, including fish, with representatives of two families, Cichlidae and Alestidae. Although the two families were previously briefly reported from Bukwa, we here give a more detailed account of the fishes based on newly collected material. The cichlid material, mainly composed of vertebrae, can be tentatively assigned to one or more species of Pseudocrenilabrinae. The alestid material, comprising a diversity of teeth, likely represents several different species of Alestes, Brycinus, and/or Bryconaethiops. Although the ichthyofaunal diversity of Bukwa is low, the fishes are important for indicating the paleoenvironment and hydrographic connections of Bukwa. The early Miocene was a critical time for African faunas, because it was during this time that the Afro-Arabian and Eurasian plates came into contact with one another, ending the long isolation of Africa, which, along with rifting in E...

Fossils recently found in the Late Miocene of Sahabi, Libya, are attributed to the extinct species Semlikiichthys rhachirhinchus. This study enriches our knowledge of the anatomy of this species. The hyomandibula and, putatively, the operculum are for the first time attributed to Semlikiichthys. The fragile laminar supraoccipital crest in the dorsicranium is preserved complete. The material from Sahabi described here extends the Late Miocene distribution of the species to the north and west to include Libya. The paleobiogeographic distribution of Semlikiichthys in Africa, and the freshwater faunal connections between different hydrographical basins in north central Africa, are discussed.

Recent field expeditions have led to the discovery of a selachian assemblage from the earliest Miocene (Aquitanian) deposits of the Uitpa Formation in the La Guajira Peninsula, Colombia. This elasmobranch assemblage provides a unique glimpse into the Caribbean biodiversity at the onset of the Neogene. The assemblage consists of 13 taxa, of which some are reported from Miocene deposits for the very first time. There are also new records of taxa the in southern Caribbean region. The taxonomic composition of the selachian assemblage was used to conduct a paleoenvironmental and paleobathymetric analysis of the lower Uitpa Formation. The maximum likelihood estimation of paleobathymetry suggests that the lower part of the Uitpa Formation was probably accumulated at a water depth of 100 to 200 m. This indicates a rapid increase in relative sea level or basin deepening, providing new insights into the possible causes of marine biota changes in the Cocinetas Basin during the Oligocene/Miocene transition.

Current knowledge about the evolutionary morphology of the vertebrate gastrointestinal tract (GIT) is hindered by the low preservation potential of soft tissues in fossils. Exceptionally preserved cololites of individual †Saurichthys from the Middle Triassic of Switzerland provide unique insights into the evolutionary morphology of the GIT. The GIT of †Saurichthys differed from that of other early actinopterygians and was convergent to that of some living sharks and rays, in exhibiting up to 30 turns of the spiral valve. Dissections and literature review demonstrate the phylogenetic diversity of GIT features and signs of biological factors that influence its morphology. A phylogenetically informed analysis of a dataset containing 134 taxa suggests that body size and phylogeny are important factors affecting the spiral valve turn counts. The high number of turns in the spiral valve of †Saurichthys and some recent sharks and rays reflect both energetically demanding lifestyles and the evolutionary histories of the groups.