A review of the Late Permian – Early Triassic conodont record and its significance for the end-Permian mass extinction

As a marine microfossil with a long-lasting fossil record stretching from the Cambrian to the Triassic, the tiny conodont plays an important role for the study of the end-Permian mass extinction. In the past few decades, numerous studies on Permian-Triassic conodonts have been published. This paper summarizes the progress made on high-resolution conodont biostratigraphy, timing of the mass extinction across the Permian-Triassic Boundary, conodont apparatus and phylogeny, conodont size variation, conodont oxygen isotope as well as other isotopes and chemical elements. Finally, future perspectives are also discussed

Changes in size and growth rate of "Lilliput'' animals in the earliest Triassic

Marine invertebrate taxa that survived the late Permian (latest Changhsingian) mass extinction event are all much smaller than they were prior to the event, an example of the Lilliput effect. New taxa that first appeared in the immediate extinction aftermath are also small compared to their size in younger strata. The Lilliput effect is a temporary phenomenon, with most surviving taxa returning to pre-extinction size in the first two conodont zones of the Triassic. In this study, the growth rates, of some of the Early Triassic Lilliput animals, estimated by growth-line analysis, were compared from different stratigraphic levels to determine how this variable fluctuated as body size returned to pre-extinction values after the event. Specimens were collected from the Mazzin and Siusi members of the Werfen Formation in northern Italy, from facies deposited in a tropical, mixed siliciclastic-carbonate ramp setting. Measurements of the bivalves Unionites and Claraia, the gastropod Bellerophon and the brachiopod '. Lingula' were made in the field, with subsequent growth-line analysis conducted on well-preserved specimens of 'Lingula'. Specimens collected from the basal Triassic Mazzin Member were smaller than those from the younger Siusi Member. Growth-line analysis indicates that the smaller Mazzin Member specimens had a greater number of more closely spaced growth lines than the larger Siusi Member specimens. The small, 'Lilliput' animals living in the immediate aftermath of the Late Permian event therefore suffered more interruptions to growth and had overall slower growth rates than larger individuals living in later recovery times. Frequent interruptions to growth and an overall slower growth rate in specimens from the Hindeodus parvus and Isarcicella isarcica zones of the Mazzin Member (lower Induan) reflects suboptimal environmental conditions, such as the frequency or severity of low-oxygen episodes, temperature extremes, and/or disruptions to primary productivity. © 2010 Elsevier B.V

A new diverse shark fauna from the Wordian (Middle Permian) Khuff Formation in the interior Haushi-Huqf area, Sultanate of Oman

Chondrichthyans are newly reported from the autochthonous Wordian Khuff Formation (middle Permian), cropping out in well-exposed, low-palaeolatitude sections in the interior Haushi-Huqf area of Oman. The shark remains comprise isolated teeth, dermal denticles and fin spines and have been recovered by processing limestone in buffered acetic acid from bulk rock samples. The fauna consists of mainly ctenacanthiform and hybodontiform taxa, identified as Glikmanius cf. myachkovensis, Glikmanius culmenis sp. nov., Omanoselache hendersoni gen. et sp. nov., Omanoselache angiolinii gen. et sp. nov., cf. Omanoselache sp., Reesodus underwoodi gen et sp. nov., Teresodus amplexus gen. et sp. nov., Gunnellodus bellistriatus, Khuffia lenis gen. et sp. nov., Khuffia prolixa gen. et sp. nov. and Euselachii sp. indet. Additional specimens include rare teeth of the lonchidiid cf. \u2018Palaeozoic Genus 1\u2019 sp., of the neoselachian Cooleyella cf. fordi and a further indeterminate neoselachian, of an indeterminate petalodont and of the holocephalan Deltodus aff. mercurei and Solenodus cf. crenulatus. Fin spines add a further two taxa, Nemacanthus sp. and Amelacanthus cf. sulcatus, which have neoselachian affinities and therefore an unclear relationship to the recovered teeth. The occurrence of Nemacanthus within this Wordian fauna represents the oldest record of this taxon and its only known occurrence in the Palaeozoic. Of the remaining genera, Glikmanius has previously been recorded from the Wordian, whereas for all the others, this study represents their youngest known stratigraphic occurrence and first occurrence in Guadalupian (middle Permian) strata. This adds significantly to our knowledge of the global diversity of chondrichthyans preceding the end-Guadalupian biotic crisis. Palaeogeographically, for all taxa, this study represents the first record from the western fringe of the marine Neotethyan basin, and only Cooleyella was previously known from the southern (Gondwanan) part of the Pangaean continental margin

Hierarchical random walks in trace fossils and the origin of optimal search behavior

Efficient searching is crucial for timely location of food and other resources. Recent studies show that diverse living animals use a theoretically optimal scale-free random search for sparse resources known as a Lévy walk, but little is known of the origins and evolution of foraging behavior and the search strategies of extinct organisms. Here, using simulations of self-avoiding trace fossil trails, we show that randomly introduced strophotaxis (U-turns)—initiated by obstructions such as self-trail avoidance or innate cueing—leads to random looping patterns with clustering across increasing scales that is consistent with the presence of Lévy walks. This predicts that optimal Lévy searches may emerge from simple behaviors observed in fossil trails. We then analyzed fossilized trails of benthic marine organisms by using a novel path analysis technique and find the first evidence, to our knowledge, of Lévy-like search strategies in extinct animals. Our results show that simple search behaviors of extinct animals in heterogeneous environments give rise to hierarchically nested Brownian walk clusters that converge to optimal Lévy patterns. Primary productivity collapse and large-scale food scarcity characterizing mass extinctions evident in the fossil record may have triggered adaptation of optimal Lévy-like searches. The findings suggest that Lévy-like behavior has been used by foragers since at least the Eocene but may have a more ancient origin, which might explain recent widespread observations of such patterns among modern taxa