Laszlo Kocsis | University of Brunei Darussalam (original) (raw)

Papers by Laszlo Kocsis

Swiss Journal of Palaeontology, Aug 22, 2023

Fragmenta Palaeontologica Hungarica

The Nyirád I. outcrop is extremely rich in fossils of marine vertebrates, including chondrichthya... more The Nyirád I. outcrop is extremely rich in fossils of marine vertebrates, including chondrichthyans, osteichthyans and marine mammals. Rarely, remains of terrestrial vertebrates are also found. The present paper adds important data to the vertebrate faunal list of the two Badenian formations of the outcrop, namely the Pusztamiske and Leitha Limestone Formations. Altogether, remains of 38 chondrichthyan and 13 osteichthyan taxa, cetaceans and two terrestrial tetrapods have been documented from the outcrop so far. The most important new result is the occurrence of teeth most similar to those of the tiger shark Galeocerdo cuvier. Th is data provides the first evidence from the Badenian of the Central Paratethys for the co-existence of two species of the genus Galeocerdo in the same habitat. With 141 figures and 1 table.

Journal of Systematic Palaeontology, 2018

The highest biodiversity of marine fishes occurs in Southeast Asia in the Indo-Australian Archipe... more The highest biodiversity of marine fishes occurs in Southeast Asia in the Indo-Australian Archipelago (IAA). However, the fossil record of fishes is very sparse and extremely incomplete in the IAA. Here we present a diverse fossil cartilaginous fish fauna from Borneo, found in late Miocene sediments in Brunei Darussalam. This fauna provides the first insight into the types of fishes that existed in the IAA region about 6.5-8 million years ago. The chondrichthyan remains belong to 24 selachian and batoid taxa. The shark fauna is dominated by Carcharhiniformes, comprising three families with at least 12 taxa, most related to modern species: Hemigaleidae (one species), Carcharhinidae (nine) and Sphyrnidae (two). In addition, the teeth of one Lamniformes shark, the extinct giant macro-predator Otodus (Megaselachus) megalodon, are present in the fauna. The batoids are dominated by Myliobatiformes from the following families: Dasyatidae (three species), Aetobatidae (one), Myliobatidae (three), Rhinopteridae (one), while three taxa of the order Rhinopristiformes were also recovered: Pristidae (one species), and Rhinidae (two). Such diversity of fossil cartilaginous fish has never before been reported from the tropical region of Southeast Asia. The dominance of the carcharhinid sharks and small rays suggests a shallow marine, coastal palaeoenvironment. The presence of the freshwater shark genus Glyphis indicates a nearby fluvial influence. Some species of the ray genera, such as Himantura or Pastinachus, have also been reported from estuaries and fresh water. The lack of some generally common Neogene taxa, such as Odontaspididae, Lamnidae and Alopidae, may be linked to such local factors and the coastal shallow-water environment.

Fragmenta Palaeontologica Hungarica, 2016

Palaeogeography, Palaeoclimatology, Palaeoecology, 2021

We performed different geochemical analyses of Paleogene terrestrial mammal remains to establish ... more We performed different geochemical analyses of Paleogene terrestrial mammal remains to establish their taphonomy, stratigraphic provenance, and palaeoenvironmental conditions. Rare earth element (REE) results indicate a similar diagenetic history to that of previously investigated marine taxa from these beds. Therefore, the mammal remains were initially deposited in a marine setting, and probably not long after the death of the animals their bodies were washed into the sea. The Ce/Ce* and Pr/Pr* ratios for the mammal fossils were compared with the background dataset from the phosphate mines, which varies with time. This allowed us to characterize the stratigraphic levels bearing the fossils. The provenances of fossils with known origins were confirmed, while remains with unknown origins could be assigned to certain stratigraphic horizons that are compatible with previously proposed phylogenic relationships. Marine diagenesis affected the various skeletal tissues differently, with the largest alteration in the bone and the least or none in the enamel. This is mostly demonstrated by the high F concentration, high Ca/P, and seawater related 87 Sr/ 86 Sr in the bone/dentine samples. Enamel shows the opposite, and retained the most pristine terrestrial values. The δ 18 O PO4 and δ 13 C results from mammal enamel revealed warm (>20°C mean annual temperature-MAT) and dry (<500mm mean annual precipitation) conditions for Paleocene-Eocene period in the region. From the early to mid-Ypresian about +5°C ∆MAT is recorded that might be linked to the Early Eocene Climatic Optimum. Furthermore, the 87 Sr/ 86 Sr ratios derived from shark tooth enameloid fit the global open ocean Sr-isotope record during the latest Paleocene and early Eocene providing further evidence for the age of these phosphate beds in the Ouled Abdoun Basin. However, older marine fossils yielded higher ratios than the global Sr-isotope curve, reflecting an alteration and/or somewhat restricted conditions in the Moroccan coastal basins, possibly triggered by global sea-level changes.

Bulletin Of The Geological Society Of Malaysia, 2020

The study aims to get some additional knowledge on the modern seafloor composition offshore Brune... more The study aims to get some additional knowledge on the modern seafloor composition offshore Brunei Darussalam by looking at the recent stratigraphic succession of the deposited sediments and their distribution patterns. For this reason, 10 shallow cores (22 to 46 cm thick) have been collected by scuba diving along two depth transects spanning from water depth of 20 to 60 m. One of the transects has been sampled north-northwest of the Muara village, just in front of the Brunei Bay and the other one off the coast near Tutong town, away from major sedimentary inputs. The results obtained portray two different sea bottom compositions and two different depth-related sediment distributions. The Muara transect is highly rich in mud and yielded abundant biogenic component at all investigated depths. The Tutong transect has a higher sand content but display constant changes along with depth. The sediment is mostly composed by biogenic grains such as rests of sponges, foraminifera, molluscs a...

Earth-Science Reviews, 2019

In this study we intend to provide an overview on fossilized tree resins (amber) commonly found i... more In this study we intend to provide an overview on fossilized tree resins (amber) commonly found in Southeast Asia, more particularly in the Indo-Australian Archipelago (IAA). These remains are often referred in literature as "Indonesian amber", "Borneo amber" or simply as "dammar". They are very common in the region and the Brunei Sultanate is no exception as most of its Neogene sedimentary successions contain amber-rich layers. Although amber is a common fossil in the country and in northern Borneo, to our knowledge it has not been studied in great detail so far. Here we present an account on the "Borneo Ambers" from Brunei, regarding their stratigraphic origin, basic physical properties, their interaction with the biosphere and their botanical origin using Fourier-transform infrared spectroscopy (FTIR). Additionally, a number of ambers and modern tree resins were analysed for their carbon isotope composition and a few were tested with gas chromatography. We discuss the results in a regional and global context, in comparison with available data from the IAA. The ambers come from four different lithostratigraphic units with an age range of 12 to 3 million years (middle Miocene to Pliocene). Recently reworked ambers from the coast, ambers from younger alluvial deposits, and several modern tree resins from Dipterocarpaceae and Araucariaceae (Agathis borneensis) were also included in the study. The more than 60 FTIR analyses of modern and fossil specimens suggest that all the Brunei ambers were produced by trees of Dipterocarpaceae. There is no indication of Agathis in the fossil record, in agreement with their lower abundance in the forests of Borneo. Modern and fossil dipterocarp resins were found to be different based on the following criteria: (1) Different reactions to solubility, hot needle and UV tests with faster reaction time and less fluorescence for the modern ones; (2) Clear distinction based on certain FTIR absorbance band ratios, mostly by those that represent carboxylic acids and esters (e.g., ~1700 and 1243 cm-1); (3) Modern resin yielded on an average 3 ‰ lower δ 13 C values, (4) Gas chromatography data reflect maturation differences among the samples. Although there is some overlap in the chemical results between the two groups, generally all these differences reflect different maturation stages of the resinous material and point towards loss of low δ 13 C components from the organic structure of the resin. The minor timewise decreasing trend in average δ 13 C from the late middle Miocene to late Miocene can be explained by (1) gradual changes in local environmental conditions, and/or (2) increased amount of less mature specimens among the younger samples. In contrast, the highest obtained δ 13 C values were found in the youngest Pliocene ambers. Instead of maturation bias this can be linked to environmental factors such as cooler-drier climate with increased seasonality, probably reflecting the onset of the northern hemisphere glaciation.

Biogeosciences, 2019

The Cocinetas Basin is located on the eastern flank of the Guajira Peninsula, northern Colombia (... more The Cocinetas Basin is located on the eastern flank of the Guajira Peninsula, northern Colombia (southern Caribbean). During the late Oligocene through the Pliocene, much of the basin was submerged. The extensive deposits in this area suggest a transition from a shallow marine to a fluvio-deltaic system, with a rich record of invertebrate and vertebrate fauna. The elasmobranch assemblages of the early Miocene to the late Pliocene succession in the Cocinetas Basin (Jimol, Castilletes and Ware formations, as well as the Patsúa Valley) are described for the first time. The assemblages include at least 30 taxa of sharks (Squaliformes, Pristiophoriformes, Orectolobiformes, Lamniformes and Carcharhiniformes) and batoids (Rhinopristiformes and Myliobatiformes), of which 24 taxa are reported from the Colombian Neogene for the first time. Paleoecological interpretations are based on the feeding ecology and on estimates of the paleohydrology (relative salinity, temperature) using stable isotope compositions of oxygen in the bioapatite of shark teeth. The isotopic composition of the studied specimens corroborates paleoenvironmental settings for the studied units that were previously estimated based on the sedimentology and biology of the taxa. These Neogene elasmobranch assemblages from the Cocinetas Basin provide new insights into the diversity the sharks and rays inhabiting the coastal and estuarine environments of the northwestern margin of South America, both during the existence of the gateway between the Atlantic and Pacific oceans and following its closure.

Journal of Asian Earth Sciences, 2019

Palaeonvironmental interpretations and biostratigraphic zonations in northwest Borneo are still a... more Palaeonvironmental interpretations and biostratigraphic zonations in northwest Borneo are still a matter of debate but are important for petroleum related applications. The outcrop of Ambug Hill, a late Miocene marine siliciclastic sequence in Brunei Darussalam, has been investigated for its foraminifera assemblage. From a 9.5 m clay-rich interval 50 taxa have been recognized and classified, whenever possible to species level. The studied fauna is characterized by mostly hyaline foraminifera, dominated by two rotaliid species: Cavarotalia annectens and Heterolepa dutemplei. Additionally, a number of miliolids, lageniids, bolivinids and also planktonic foraminifera are present but in much lower abundance. The dominance of the rotaliids points to a sea floor rich in organic carbon characterized by muddy substrates with very low light penetration and the possible growth of patchy sea grass or macroalgae in the system, as indicated by epiphytic foraminifera in the samples. The results obtained give additional insights on how the environmental conditions might have been during the deposition of the deltaic sequences very widespread in the region, and how the fauna coped with such settings. Throughout the investigated samples, the dominance of the assemblages clearly shows alternating stress conditions, typical of pro-deltaic environments. The large abundance of rotaliid foraminifera, points toward possible biostratigraphic applications as several taxa within this group have short biozones in the region even though have strong facies dependency. If their role as biostratigraphic indicators could be finally proven, they might be used to date the large depositional sequences occurring in the region, since planktonic index fossils are scarce due to the very proximal settings of the sediments. their base, referred to as offshore transitions or prodelta deposits (e.g., Back et al., 2001), then, shallowing upward, they pass into laminated sandier deposits typical of lower shoreface environments and are

Geologica Carpathica, 2016

A new Middle Miocene (Langhian - early Serravallian) assemblage with shark and ray teeth from Nyi... more A new Middle Miocene (Langhian - early Serravallian) assemblage with shark and ray teeth from Nyirád (Hungary, Transdanubia, Veszprém County) consists of nine families, with 15 different species. The assemblage shares many common genera with other Middle Miocene assemblages in the Paratethys (Notorynchus, Carcharias, Otodus, Cosmopolitodus, Hemipristis, Galeocerdo, Carcharhinus, and Aetobatus), and reflects a subtropical climate and a close connection with the Mediterranean Sea. However, a detailed faunal compilation of Miocene selachians reveals that several taxa that were still present in the Mediterranean or lived in the Paratethys during the Lower Miocene disappeared or became very rare by the Middle Miocene in the Central Paratethys (e.g., Isistius, Centrophorus, Mitsukurina, Carcharoides, Parotodus, Alopias). The taxa that went locally extinct in the Paratethys are mainly represented by deep-water or pelagic forms. Their disappearance is most probably related to the gradual se...

Quaternary Science Reviews, 2017

The Pliocene and Early Pleistocene (5.2 to 1 Ma) palaeoclimate for localities in Italy is evaluat... more The Pliocene and Early Pleistocene (5.2 to 1 Ma) palaeoclimate for localities in Italy is evaluated using stable carbon and oxygen isotope compositions of tooth enamel of fossil specimens from Rhinocerotidae (Stephanorhinus sp.) and Gomphotheriidae (Anancus sp.) taxa. Carbon isotope composition was measured in the structural carbonate (δ 13 C), while oxygen isotope values were determined both in the structural carbonate (δ 18 O CO3) and the phosphate (δ 18 O PO4) of bioapatite. The δ 13 C CO3 values indicate that the taxa were grazers-browsers of a pure C 3 vegetation. Low δ 13 C CO3 values for Central and North Italy indicate a humid climate with woodlands and forest cover in the Pliocene. For northern localities the δ 13 C values increase between MN16a and MNQ16b biozones most likely linked to the Northern Hemisphere Glaciation at 2.7 Ma after the "Mid-Pliocene Warm Period". For Central Italy the values have a wide range with a long term increasing trend in the Early Pleistocene, indicating more arid climate and / or more open vegetation. Overall, the δ 18 O PO4 values in Central Italy change together with the δ 13 C CO3 values and are taken to reflect the warmer / wetter interglacials and cooler / more arid glacial phases. The δ 18 O PO4 values in North Italy are lower than those in Central Italy and show no clear temporal trend. One explanation for the low values especially in MN14-15 biozone is that these δ 18 O PO4 values do not reflect entirely the isotopic composition of local precipitation but river waters from the Alps with 18 O-depleted isotopic compositions or a N-S directed rain-shadow effect on the precipitation. In general the new isotope data agree well with palaeoclimate reconstructions based on palynological and other proxies.

Földtani Közlöny

Chondrichthyans and osteichthyans are widely reported from marine sediments of the Central Parate... more Chondrichthyans and osteichthyans are widely reported from marine sediments of the Central Paratethys, not only by sporadic occurrences, but also by complex, diverse fish assemblages. Here we present a rich fish fauna from the upper Miocene (Pannonian, Tortonian) lacustrine sediments exposed in the Pécs-Danitzpuszta sand pit, in the SW Pannonian Basin. Altogether 22 227 specimens were investigated, and they could be classified into 17 chondrichthyan and 16 osteichthyan taxa. Among the chondrichthyans Odontaspididae (55.51%) and Myliobatidae (14.4%) are the most abundant, while the bony fishes are dominated by the Sparidae (77.07%). The limonitic, yellow, coarse-grained, gravelly sands yielded an extremely large amount of isolated fish fossils. A considerable part of the vertebrate material of the sands is likely reworked from older, middle Miocene (Badenian and Sarmatian, i.e. Langhian and Serravallian) sediments. The late Miocene calcareous marls underlying the sands also yielded a...

Paleobiology

Here we report high-latitude stable isotope compositions of Maastrichtian fossil fish and marine ... more Here we report high-latitude stable isotope compositions of Maastrichtian fossil fish and marine reptiles (mainly mosasaurs) from Antarctica (64°S paleolatitude) and compare them with mid-paleolatitude samples from Argentine Patagonia (45°S). Disparities between the δ13C values of bony fish and marine reptiles correspond to differences in the foraging ground (distance from the shore and depth), while dramatically higher δ13C values (by 18‰) in shark enameloid cannot be explained through ecology and are here imputed to biomineralization. Comparison with extant vertebrates suggests that the diet alone can explain the offset observed between bony fish and mosasaurs; however, breath holding due to a diving behavior in mosasaurs may have had some impact on their δ13C values, as previously suggested. The δ18OPO4 values of the remains confirm a relatively stable, elevated body temperature for marine reptiles, meaning that they were thermoregulators. We calculated a water temperature of ~8°...

Palaeontographica Abteilung A

Neues Jahrbuch für Geologie und Paläontologie - Monatshefte

Palaeogeography, Palaeoclimatology, Palaeoecology, 2015

Abstract Stable carbon and oxygen isotope values of structural carbonate (δ13C, δ18OCO3) and phos... more Abstract Stable carbon and oxygen isotope values of structural carbonate (δ13C, δ18OCO3) and phosphate (δ18OPO4) in bio-apatite were measured for fossil mammalian teeth from Slovakia and Hungary. Oxygen isotope compositions of enamel provide new quantitative records of the Pliocene and Early Pleistocene paleoclimate in the Pannonian Basin (PB). The δ18OPO4 values were used to study the temporal variations in the oxygen isotope compositions of precipitation and the changes in temperature over the PB. The new O-isotope data suggest that surface air temperatures between 4.5 and 2.0 Ma were 1 to 4 °C warmer with about 700 mm/yr more precipitation compared to the present. C-isotope analyses of samples from proboscideans (Anancus sp., Mammut sp.) and perissodactyls (Stephanorhinus sp., Tapirus sp.) from the Pliocene (MN15–MN16) and Early Pleistocene (MN17) suggest that they were primarily C3 browsers. The mean δ13C value is high at 4.5 to 3.7 Ma (MN14–15) during the Pliocene Warm Period and decreases at about 3.5 to 3.0 Ma (MN16; mid-Pliocene Warm Period), with the onset of more humid conditions in Europe. The δ13C values return to higher values from 2.5 Ma onwards (MN17), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation.

Environmental Biology of Fishes, 2015

Bull sharks Carcharhinus leucas use estuarine and riverine systems as nursery habitat. The Shark ... more Bull sharks Carcharhinus leucas use estuarine and riverine systems as nursery habitat. The Shark Reef Marine Reserve (SRMR) on the southern coast of Viti Levu, Fiji, is well-known for its adult bull shark population. The species’ seasonal departure from the SRMR is related to reproductive activity, but nursery grounds have not yet been identified on the southern coast of Viti Levu. In order to further identify and characterise bull shark habitats in Fiji, 49 teeth were collected from bull sharks encountered at the SRMR and measured for their trace element concentrations, and 22 of them for oxygen isotopic composition in the phosphate group of bioapatite. The trace element analyses yielded relatively high Na, Mg, Sr, and F and low Ba concentrations for all the teeth supporting formation in marine environment. The phosphate oxygen isotope data concur with this result and the data evidently show that these teeth developed under marine condition relating to the temperature and oxygen isotopic composition of Fiji’s coastal waters. Therefore, the investigated teeth show no signs of freshwater habitat. Our results do not support the hypothesis that bull sharks enter freshwater habitats, at least not for longer time periods, during their absence from the SRMR. Additionally, the bull shark teeth had unexpectedly high zinc concentration at the very edge of the enameloid. This cannot be explained by environmental factors; therefore the high Zn content is interpreted here as a result of biological process, a reflection of enzyme (i.e., KLK4) related organic matter removal and enhanced crystallization during tooth maturation.