[Paleontology • 2026] Climate-extreme-driven Genesis of A Cretaceous Dinosaur Lagerstätte

 

 in Fanti, Consorti, Muscioni, Baldassari, Dinelli, Polentarutti, ... et Chiarenza. 2026. 

DOI: doi.org/10.1016/j.gloplacha.2026.105589 

 x.com/AAlechiarenza

Artwork by palaeoartist Davide Bonadonna

Highlights: 

• Monsoon-driven storms created a Cretaceous dinosaur Lagerstätte.

• Tidal microcouplets yield an unprecedented ∼40-year chronometry.

• Synchrotron micro-XRF/XRD maps refute seasonal varve interpretation.

• Microbial mats enabled rapid sealing and exceptional soft-tissue preservation.

• New genetic model and toolkit for climate event-driven preservation in carbonates.

Abstract

Konservat-Lagerstätten provide exceptional records of past ecosystems, yet the environmental and climatic processes governing their formation in extreme climatic regimes remain a significant, unresolved conundrum. Here we present a novel, process-based mechanism for the Villaggio del Pescatore Konservat-Lagerstätte (northeastern Italy; Late Cretaceous, 80 Ma), which preserves a diverse terrestrial and aquatic biota. Integrating high resolution synchrotron micro-analyses, bulk geochemistry, detailed taphonomy and palaeoclimate simulations we identify a dynamic, monsoon-paced tidal flat ecosystem within a carbonate coastal margin. Field and core records comprise metrescale packages of laterally persistent light–dark laminae; microstratigraphic, spectral and statistical analyses indicate a semidiurnal tidal regime with neap–spring modulation. MicroXRF/XRD mapping reveals that individual microlaminae within couplets share the same elemental inventory refuting a seasonal varve origin. Laminae chronometry, tied to the tidal interpretation, constrains net accumulation of the fossil bearing rhythmites to decadal (∼40 year) timescales. Geochemical proxies record alternating terrigenous rich, high TOC intervals and drier, better oxygenated intervals. Palaeoclimate model ensembles diagnose a vigorous, summer dominated monsoon domain at ∼29° N under greenhouse boundary conditions. We document that episodic monsoon enhanced flood and tropical cyclone pulses delivered sediment, nutrients, carcasses and plant debris to a microbially active, carbonate tidal flat; microbial mats rapidly stabilised and promoted early cementation, enabling exceptional soft tissue preservation. We propose a genetic model in which monsoon–cyclone forcing, tidal trapping and microbial sealing combine to produce decadal, daily resolved vertebrate Lagerstätten in greenhouse settings, offering predictive targets for similar deposits and deep time analogues for modern coastal change.

Keywords: Exceptional fossil preservation, Dinosauria, Crocodylomorpha, Arthropoda, Plants, Italy

“Stormbringer” — palaeoenvironmental reconstruction of Villaggio del Pescatore
The artwork shows a Tethyshadros insularis carcass and an Acynodon crocodylian on a storm-swept tropical tidal flat, beneath the monsoon clouds and a distant cyclone that the study identifies as the engine of the site’s formation.

 by palaeoartist Davide Bonadonna. 

 

Federico Fanti, Lorenzo Consorti, Marco Muscioni, Lorenzo Baldassari, Enrico Dinelli, Maurizio Polentarutti, Giorgio Bais, Alexander Farnsworth, Evelyn Kustatscher, Amalia Spina and Alfio Alessandro Chiarenza. 2026. Climate-extreme-driven Genesis of A Cretaceous Dinosaur Lagerstätte. Global and Planetary Change.  265, October 2026, 105589. DOI: doi.org/10.1016/j.gloplacha.2026.105589

 x.com/AAlechiarenza/status/2074802383733813269

[PaleoIchthyology • 2026] The Oldest Shark Face—Anatomy of the Devonian elasmobranch Phoebodus

Phoebodus saidselachus Frey, Coates, Ginter, Hairapetian, Rücklin, Jerjen & Klug, 2019

in Klug, Greif, Pohle, Ginter, Coates, Haouz, Lagnaoui, Pople et Frey, 2026. 

www.app.pan.pl/article/item/app012902025.html 

Phoebodus was recognized as the earliest elasmobranch known from articulated remains, a group which constitutes most modern cartilaginous fish comprising sharks, skates and rays. Its elongate body, the presence of two dorsal fins with fin spines, and the elongate head had already been described. Based on spectacularly well-preserved fossils, we add new anatomical information on its exact body proportions, the paired and caudal fins, the dermal denticles, the skull morphology, the endocast, and the gill skeleton. These new skeletons from the Famennian (Upper Devonian) of Morocco (c. 367 Ma) permit a much-improved reconstruction of the anatomy of Phoebodus. The new materials comprise the oldest elasmobranch specimens preserving the complete head in three dimensions. Additionally, the new materials yield information about growth and diet and thus position in the trophic network. Despite the newly coded characters, the phylogenetic position of the genus Phoebodus with the oldest teeth dating to the early Givetian remains that of the oldest stem-elasmobranch in the Bayesian analyses.

Key words: Chondrichthyes, Elasmobranchii, Famennian, ontogeny, exceptional preservation, Fossillagerstätten

Phoebodontiform elasmobranch Phoebodus saidselachus Frey et al., 2019a, middle Famennian, Upper Devonian, southern Maïder, Anti-Atlas, Morocco. A. PIMUZ A/I 5751, prep. T. Imhof, largest individual, nearly complete. B. PIMUZ A/I 5752, prep. T. Imhof, second largest individual, only caudal region missing; for details of the skull see Fig. 2. C. PIMUZ A/I 5753, prep. M. Greif, anterior half, excellent integument, fins and brachial region. D. PIMUZ A/I 5754, prep. R. Roth, two superimposed chondrichthyans; the skull in the middle is Maghriboselache mohamezanei with further remains; the straight, complete skeleton belongs to Phoebodus; the latter preserves the caudal fin. E. PIMUZ A/I 4712, holotype, smallest skeleton, nearly complete, modified after Frey et al. (2019a).

Skeletal reconstruction of the phoebodontiform elasmobranch Phoebodus saidselachus Frey et al., 2019a, middle Famennian, Upper Devonian, southern Maïder, Anti-Atlas, Morocco. A. PIMUZ A/I 5754, caudalis. B, C. PIMUZ A/I 4712, posterior and anterior dorsal fins. D. PIMUZ A/I 5752, anterior dorsal fin. E. PIMUZ A/I 5751, caudalis. F, G. PIMUZ A/I 5753, pectoral fin and branchial basket. H. PIMUZ A/I 5752, head. The photos are not to scale. The scale refers only to the drawing.

Systematic palaeontology 

Chondrichthyes Huxley, 1880 

Elasmobranchii Bonaparte, 1838 

Phoebodontiformes Ginter et al., 2010 

Genus Phoebodus St. John & Worthen, 1875

Reconstructions of an adult female and juvenile male of the phoebodontiform elasmobranch Phoebodus saidselachus Frey et al., 2019a, middle Famennian, Upper Devonian, southern Maïder, Anti-Atlas, Morocco. We incorporated the new anatomical details particularly in the proportions and the fin shapes. The juvenile is reconstructed after the holotype.

  

Christian Klug, Merle Greif, Alexander Pohle, Michał Ginter, Michael I. Coates, Wahiba Bel Haouz, Abdelouahed Lagnaoui, Jonathan Pople, and Linda Frey. 2026. The Oldest Shark Face—Anatomy of the Devonian elasmobranch Phoebodus. Acta Palaeontologica Polonica. 71 (2), 2026: 399-430 DOI:10.4202/app.01290.2025  https://www.app.pan.pl/article/item/app012902025.html

Linda Frey, Michael Coates, Michał Ginter, Vachik Hairapetian, Martin Rücklin, Iwan Jerjen, Christian Klug. 2019. The early elasmobranch Phoebodus: phylogenetic relationships, ecomorphology and a new time-scale for shark evolution. Proc Biol Sci. 286 (1912): 20191336. DOI: doi.org/10.1098/rspb.2019.1336

[Paleontology • 2026] Megachelicerax cousteaui • A Chelicera-bearing Arthropod reveals the Cambrian Origin of Chelicerates

Megachelicerax cousteaui

Lerosey-Aubril & Ortega-Hernández, 2026

DOI: doi.org/10.1038/s41586-026-10284-2 

Artistic reconstruction by Masato Hattori 

Abstract

Chelicerata is a megadiverse (over 120,000 species) arthropod clade that includes familiar taxa of profound ecological and economic importance, such as scorpions, spiders and mites. Extant chelicerates share a unique anatomical character, the chelicerae—feeding first appendages terminated by a simple pincer-like chela. The fossil record of these primarily predatory animals spans almost 500 million years, suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods4,5,6, megacheirans, habeliids and mollisoniids have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan’s origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.

 

Megachelicerax cousteaui gen. et sp. nov.

Megachelicerax cousteaui. 
 Artistic reconstruction by Masato Hattori (© Harvard University).

Rudy Lerosey-Aubril and Javier Ortega-Hernández. 2026. A Chelicera-bearing Arthropod reveals the Cambrian Origin of Chelicerates. Nature.  DOI: doi.org/10.1038/s41586-026-10284-2  [01 April 2026]

[PaleoIchthyology • 2026] Eosteus chongqingensis • The Oldest articulated Bony Fish from the early Silurian period

 

 Eosteus chongqingensis

Y.-A. Zhu, Chen, Li, Zhao, Zhou, Jia, Y.-L. Yu, H.-X. Yu, Wei, Ahlberg, Lu & M. Zhu, 2026

DOI: doi.org/10.1038/s41586-026-10125-2

Life reconstruction by NICE PaleoVislab, IVPP

Abstract

Osteichthyans, comprising sarcopterygians and actinopterygians, dominate modern vertebrate biodiversity, yet their pre-Devonian fossil record remains scarce and fragmentary. The oldest articulated sarcopterygian and stem osteichthyan date to the late Silurian, whereas undisputed actinopterygian fossils in articulation appear only in the Middle Devonian. Here we report an articulated, near-complete osteichthyan from the early Silurian Chongqing Lagerstätte (approximately 436 million years ago), representing the oldest osteichthyan occurrence including microfossils. This tiny fish exhibits a fusiform, generalized osteichthyan body outline, with plesiomorphic osteichthyan characters, including the lack of lepidotrichia and the presence of serial median dorsal plates, pectoral and dorsal fin spines and an anal fin spine reported previously exclusively in stem chondrichthyans and one placoderm. It also displays features, such as a single dorsal fin and caudal fulcra, seen commonly in actinopterygians. Bayesian inference and the 50% majority rule consensus of the maximum-parsimony analysis place the new fish on the osteichthyan stem, whereas the strict consensus leaves its position unresolved within osteichthyans. This discovery increases Silurian osteichthyan diversity and further populates the osteichthyan stem group. The morphological disparity among early osteichthyans implies a more extensive Silurian to Early Devonian radiation of bony fishes than previous lines of evidence suggested.

Morphological evolution of early jawed vertebrates, showing the position of Eosteus and Megamastax among stem bony fishes. 

Eosteus chongqingensis

Life reconstruction of the oldest osteichthyan Eosteus chongqingensis.

 Credit: NICE PaleoVislab, IVPP

Life reconstruction of the biggest Silurian vertebrate Megamastax amblyodus.

Credit: Image by NICE PaleoVislab, IVPP

 

You-An Zhu, Yang Chen, Qiang Li, Wen-Jin Zhao, Zheng-Da Zhou, Lian-Tao Jia, Yi-Lun Yu, Han-Xin Yu, Guang-Biao Wei, Per E. Ahlberg, Jing Lu and Min Zhu. 2026. The Oldest articulated Bony Fish from the early Silurian period. Nature. 651; 128–134. DOI: doi.org/10.1038/s41586-026-10125-2 [04 March 2026]

[Paleontology • 2024] Sphenoecium marjumensis & Tarnagraptus cupidus • Benthic pterobranchs from the Cambrian (Drumian) Marjum Konservat-Lagerstätte of Utah, USA

Sphenoecium marjumensis  &
 Tarnagraptus cupidus 

Lerosey-Aubril, Maletz, Coleman, Mouro, Gaines, Skabelund & Ortega-Hernández, 2024

 

DOI: doi.org/10.1002/spp2.1555 

 ortega-hernandezlab.oeb.harvard.edu

 x.com/PlLife2

Abstract

Pterobranchs are rare in Cambrian strata of North America despite discoveries of more than 30 exceptionally preserved fossil biotas. Miaolingian pterobranchs from this continent typically form low-diversity and low-abundance assemblages. Here we describe an abundant pterobranch material from the Drumian Marjum Formation recently collected at the Gray Marjum Quarry in the House Range of Utah, USA. The faunule is composed of two new species: Sphenoecium marjumensis, an encrusting representative forming compact bushy colonies of more than 80 tubes with poorly developed rhizomes, and Tarnagraptus cupidus, an erect growing taxon characterized by intertwining stems and a monopodial colonial growth. Known in extant rhabdopleurids, this mode of colonial growth had hitherto never been observed in fossil pterobranchs. Its documentation in a c. 500-myr-old taxon attests to its deep origin in the evolutionary history of the group. Although the new species almost exclusively occur in the Marjum strata, this pterobranch faunule is broadly similar to those recovered from other Miaolingian Burgess Shale-type deposits of North America in terms of genus-level composition, species richness, and ecological structure. This may indicate that pterobranchs were poorly diverse components of animal communities at that time, or that they mostly thrived in more proximal shelf environments where conditions conducive to their preservation rarely developed. The common co-occurrence of taxa with fundamentally different ecomorphotypes in the Miaolingian Series of North America strongly suggests an earlier phase of morphological diversification of benthic pterobranchs during the early Cambrian, which remains insufficiently documented by fossils.

Keywords: Pterobranchia, Graptolithina, Marjum Formation, Konservat-Lagerstätten, Miaolingian, Drumian

 

Rudy Lerosey-Aubril, Jörg Maletz, Robert Coleman, Lucas Del Mouro, Robert R. Gaines, Jacob Skabelund and Javier Ortega-Hernández. 2024. Benthic pterobranchs from the Cambrian (Drumian) Marjum Konservat-Lagerstätte of Utah. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.1555  ortega-hernandezlab.oeb.harvard.edu/news/back-back-publications-cambrian-ordovician-lagerstätte

  x.com/InvertebratePal/status/1806687327194087599

  x.com/PlLife2/status/1790758316098117943

  x.com/ThePalAss/status/1791479826722766987

[Paleontology • 2025] Yunnanocyclus fortis • A new Induan (Early Triassic, Dienerian) cyclidan crustacean from the Guiyang Biota

Yunnanocyclus fortis 

 Sun, Schweitzer, Dai, Yuan, Bai, Tian, Chu, Guo, Chen, X. Liu, Jiang, Y. Liu, Li & Song, 2025 

 

DOI: doi.org/10.1002/spp2.70052  

 Researchgate.net/publication/397482018 

x.com/ThePalAss

Abstract 

The order Cyclida is a distinct group of crustaceans. However, our knowledge of cyclidan crustaceans is very limited due to their rarity in the fossil record. Usually, only the hard carapaces are preserved, while their antennules and appendages are extremely rare. Here, we describe a new cyclidan species, Yunnanocyclus fortis sp. nov., on the basis of three well-preserved specimens from the Early Triassic Guiyang biota, which is known as the oldest Mesozoic lagerstätte. The new species has an ovoid carapace, narrow and smooth marginal rim, a pair of antennules, antennae and seven pairs of thoracomeres. Using μ-XRF analysis, we found that the new species has a pair of strongly ovoid mandibles. The discovery of a new species from South China expands the palaeogeographic distribution of Early Triassic cyclidans. Combining the new species and other reported Cyclida morphological data, we constructed the morphospace of Cyclida using NMDS analysis. The morphospace of Cyclida shows no significant morphological innovations from the Carboniferous to the Triassic, and the high degree of morphological divergence in the Carboniferous supports the early burst model.

 Yunnanocyclus fortis sp. nov.

Xiaoyuan Sun, Carrie E. Schweitzer, Xu Dai, Zhiwei Yuan, Ruoyu Bai, Li Tian, Daoliang Chu, Wei Guo, Jing Chen, Xiaokang Liu, Shouyi Jiang, Yuting Liu, Zhe Li and Haijun Song. 2025. A new Induan (Early Triassic, Dienerian) cyclidan crustacean from the Guiyang Biota. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.70052 [10 November 2025]  

 Researchgate.net/publication/397482018_A_new_Induan_Early_Triassic_Dienerian_cyclidan_crustacean_from_the_Guiyang_biota

 x.com/ThePalAss/status/1988256523210969537

[Paleontology • 2025] Mandocaris polyphaga • A New caridean Shrimp Fossil (Caridea: Acanthephyridae) with exceptionally preserved organs from the Middle Jurassic of La Voulte-sur-Rhône, France

Mandocaris polyphaga

Lagrange, Audo, Odin, De Grave, Fernandez, Dollman & Charbonnier, 2025

www.app.pan.pl

We used propagation phase contrast synchrotron X-ray micro-computed tomography (PPC-SRμCT) on an exceptionally preserved fossil caridean from the Callovian of the La Voulte-sur-Rhône Konservat-Lagerstätte. The tomographic data reveal the shape of the mandible and pereiopodal epipods allowing the description of a new genus and species of Acanthephyridae (Caridea) shrimp, Mandocaris polyphaga gen. et sp. nov. Most organs are exceptionally preserved in either mineral denser to X-ray than matrix, interpreted to be sulfides, or in mineral of lower density than the matrix, interpreted as carbonate/phosphate such as fluorapatite. We herein propose a taphonomic scenario for the preservation of M. polyphaga gen. et sp. nov.: it died from unknown causes not caused by an injury, as no wound is visible, falling on the sediment/water interface, it laid on its right side, and was probably covered by sediments and/or a microbial mat, thus quickly becoming entombed in the anoxic zone of the sedimentary column. Once there, many anatomic structures were replaced by phosphates. Sulfides precipitated concomitantly or quickly afterwards, probably aided by both internal and external source of metal ions. The importance of the external source of metal ions (hydrothermalism) is clear due to the prevalence of sulfides in the ventral side of the specimen, an area more permeable due to its abundance in thin membranes prone to decay. The loss of integrity thereafter led to sediment invading the body cavity, thus obliterating a few ventral anatomic details, including some pereiopodal muscles, part of the hepatopancreas, most of the gills, and possibly reproductive organs. The nodule was then formed, closing the system, and protecting the specimen from further diagenetic degradation.

Key words: Crustacea, Caridea, synchrotron, tomography, anatomy, Konservat-Lagerstätte, Callovian, Middle Jurassic.

Overview of the caridean shrimp Mandocaris polyphaga gen. et sp. nov. (holotype, MNHN.F.A58277) from the Callovian (Middle Jurassic) of La Voulte, France.
Specimen in right lateral (A1) and dorsal (A2) views. Cephalothorax in right lateral view (A3). 3D reconstruction of the holotype in right lateral view (A4), exposing the organs (A5). Abbreviations: a, branchiocardiac groove; a1, antennula; a2, antenna; b1, hepatic groove; e1e, cervical groove; hc, hepatic carina; hs, hepatic spine; mxp3, third maxilliped; phc, posterior hepatic carina; P1–5, pereiopods 1–5; pl1–4, pleopods 1–4; s1–6, pleonites 1–6. White arrows point to the front of the animal.

Mandocaris polyphaga gen. et sp. nov. 

 

Flavien Lagrange, Denis Audo, Giliane P. Odin, Sammy De Grave, Vincent Fernandez, Kathleen Dollman, and Sylvain Charbonnier. 2025. A New caridean Shrimp Fossil with exceptionally preserved organs from the Middle Jurassic of La Voulte-sur-Rhône, France. Acta Palaeontologica Polonica. 70(4); 775-794. DOI: 10.4202/app.01275.2025

https://www.app.pan.pl/article/item/app012752025.html

[Paleontology • 2025] Falciscaris mumakiana • A New giant nektobenthic radiodont benthivore (Radiodonta: Hurdiidae) from the Early Ordovician Fezouata Biota in Morocco

 

Falciscaris mumakiana 

Potin, Claisse, Trébaol, Gueriau, Wu, Pates & Daley, 2025

 DOI: doi.org/10.4202/app.01278.2025 

 Researchgate.net/publication/398154837

Artwork by Alexis Trébaol

The Fezouata Shale Formation is an Early Ordovician Lagerstätte that preserved exceptionally detailed records of complex marine ecosystems, making it crucial for understanding the early evolution of animal life. It has yielded the youngest known community of radiodonts to date. This group is particularly well known from the Cambrian, with iconic representatives such as Anomalocaris, which are emblematic of the Cambrian explosion. Here we describe a new radiodont from the Fezouata Biota, Falciscaris mumakiana gen. et sp. nov. based on seven specimens of isolated frontal appendages. These appendages bear long endites with large and robust auxiliary spines, suggesting they were adapted for foraging through sediment in search of prey. The appendages of F. mumakiana gen. et sp. nov. can be relatively large compared to the majority of radiodont appendages, with endites reaching up to 11.4 cm in length, suggesting a total body size exceeding one meter for this Ordovician radiodont. In contrast, smaller specimens can be up to 10 times smaller, indicating ontogenetic stages during which the frontal appendage morphology changes little. Following the “Ordovician Plankton Revolution”, the proliferation of planktonic resources and enhanced pelagic-benthic coupling during this period likely allowed for the rise of giant suspension-feeding radiodonts, such as the Aegirocassisinae and F. mumakiana gen. et sp. nov., the new giant benthivore. In term of taxonomic diversity, benthivores radiodonts remain a minor component of radiodont diversity in the Fezouata Biota compared to the more dominant suspension feeders.

Key words: Panarthropoda, Radiodonta, Hurdiidae, gigantism, benthivores, feeding evolution, Fezouata Shale, Early Ordovician.

Superphylum Panarthropoda Nielsen, 1995 

Order Radiodonta Collins, 1996 

Family Hurdiidae Lerosey-Aubril & Pates, 2018

Hurdiid radiodont Falciscaris mumakiana gen. et sp. nov. frontal appendage, 
from the Fezouata Shale Formation, Lower Ordovician, Morocco.
YPM IP 516782a/b, holotype and paratypes 

 Genus Falciscaris nov.

Etymology: From Latin falx (genitive falcis), scythe, in recognition of the strongly curved shape of the endites tips; and Latinised Greek caris, crab, commonly used in arthropod taxonomy.

Falciscaris mumakiana sp. nov.  

 Etymology: Mûmak (plural mûmakil) is a fantasy elephant-like animal from the Tolkien universe Lord of the Rings. They are described as giant animals and are depicted in the third part of the movie trilogy as having 4 long curved tusks equipped with spines, looking like the curved and spiny endite of Falciscaris mumakiana gen. et sp. nov. 

Diagnosis.—Hurdiidae frontal appendage with at least seven podomeres: one proximal, five intermediate and one distal. Proximal podomeres rectangular, taller than long. At least six laminiform endites are present, long ones on five intermediate podomeres and a shorter one distally. Intermediate endites over twice the height of podomeres, all ending in a strongly curved, hook-like tip. Each endite bears dorsally curved auxiliary spines in at least three sizes, alternating such that spines of the same size are never adjacent.

Artistic life reconstruction of the hurdiid radiodont Falciscaris mumakiana gen. et sp. nov. 
Apart from the frontal appendages, the reconstruction is based on other related hurdiids.

by Alexis Trébaol

Gaëtan J.-M. Potin, Pénélope Claisse, Alexis Trébaol, Pierre Gueriau, Yu Wu, Stephen Pates, and Allison C. Daley. 2025. A New giant nektobenthic radiodont benthivore from the Early Ordovician Fezouata Biota in Morocco. Acta Palaeontologica Polonica. 70(4). 709-722. DOI: doi.org/10.4202/app.01278.2025 

 Researchgate.net/publication/398154837_A_new_giant_nektobenthic_radiodont_benthivore_from_the_Early_Ordovician_Fezouata_Biota_in_Morocco

[Paleontology • 2025] Oura megale • A large early Cambrian Deuteropod with a delta-shaped tailpiece

 Oura megale O’Flynn, Williams & Liu, 

in O’Flynn, Williams, Thomas, Hou et Liu, 2025. 

DOI: doi.org/10.26879/1547 

ABSTRACT

We describe Oura megale n. gen. n. sp., a large (ca. 14 cm long) euarthropod from the lower Cambrian Chengjiang Konservat-Lagerstätte of Yunnan Province, China. It possesses stalked, compound eyes and a possible raptorial frontal appendage (synapomorphies and symplesiomorphies of lower stem- and upper stem-group euarthropods, respectively), but in combination with deuteropodan synapomorphies (e.g., a multi-segmented head). Micro-X-ray fluorescence shows a thorax that consists of 10 comparatively long and five comparatively short segments. The terminal segment articulates with a large, delta-shaped tailpiece that may have conferred high positional manoeuvrability in the water column. The phylogenetic position of O. megale n. gen. n. sp. in the euarthropod stem may add support to the homology of raptorial frontal appendages between lower stem-group euarthropods and deuteropods.

Keywords: new genus; new species; Cambrian Chengjiang biota; euarthropod; micro-X-ray fluorescence; tailpiece

 Oura megale n. gen n. sp. (YKLP 17237).
A, photograph of ventral view. B, Fe map. C, composite line drawing. D, F1 map. E, P map. F, F1 map of head region. G, P map of head region.

 Abbreviations: l, left; r, right; A1, frontal appendage; ex.A6, exopod of 5th head limb on head segment 6; an, cephalic segment (n); as, anterior sclerite; cf, compactional fold; e, eye; es, eye stalk; exn, exopod (n); sn, sternite (n); Tn, thoracic exopod (n); tn, thoracic segment (n). Scale bars represent 20 mm.

SYSTEMATIC PALAEONTOLOGY

Phylum EUARTHROPODA Lankester, 1904

Unranked DEUTEROPODA Ortega-Hernández, 2016

Class, Order and Family incertae sedis

Genus OURA O’Flynn, Williams and Liu, new genus

Etymology. Gr. Oura, f. tail.

Remarks. Oura n. gen. is ascribed to Deuteropoda — as defined by a multi-segmented head and body arthrodization (Ortega-Hernández, 2016). Oura n. gen. bears: stalked, compound eyes, that is, a synapomorphy and symplesiomorphy of lower stem-group Euarthropoda and Deuteropoda, respectively (Ortega-Hernández, 2016, p. 11, table 4); and robust frontal appendages (FA, i.e., A1) that insert approximately one-half the length of the head behind the eye stalks and are inferred to be deutocerebral. The proximal-most three podomeres of the right-side frontal appendage (FA) are preserved, and these are morphologically like those of radiodonts and certain ‘great appendage’-bearing deuteropods.

Oura megale O’Flynn, Williams and Liu, new species

  

Etymology. Gr. Megale, large, great.

Diagnosis. Six cephalic segments. From anterior to posterior, these are: oblate spheroidal anterior sclerite to which large ovate paired stalked lateral eyes are attached; post-ocular segment with paired uniramous deutocerebral FAs; and four subsequent segments. FA antero-laterally orientated, consisting of ≥ three podomeres that bear elongate triangular spines. Thorax consists of 15 segments (anterior-most 10 comparatively long; posterior-most five comparatively short), each with one pair of presumed biramous appendages. Segment 15 articulated with large, ogival delta tailpiece.

Robert J. O’Flynn, Mark Williams, Ed Thomas, Xianguang Hou, and Yu Liu. 2025. Oura megale n. gen. n. sp., A large early Cambrian Deuteropod with a delta-shaped tailpiece. Palaeontologia Electronica. 28(3):a44. DOI: doi.org/10.26879/1547 

palaeo-electronica.org/content/2025/5687-early-cambrian-deuteropod-oura-megale

 x.com/PalaeoE/status/1977837034074210364

Plain Language Abstract:  Oura megale, a large arthropod (segmented, jointed-limbed animal), comparable in size to anomalocaridids (i.e., giant invertebrate Cambrian predators featuring mouthparts composed of a ring of plates), inhabited the Cambrian seas (approximately 518 million years ago) of south-western China. It had stalked eyes and a grasping frontal appendage, but in combination with a multi-segmented head, as we see in, for example, modern insects. Palaeontological techniques show a trunk that consists of 10 long and five short segments. The rearmost segment is associated with a large, delta-shaped tail that may have been conducive to efficient swimming. The evolutionary relationships between O. megale and other arthropods may suggest that the grasping appendage (shared by several arthropods) is inherited from a common ancestor.

[Paleontology • 2025] Palaeocampa anthrax • An armored freshwater Lobopodian (Panarthropoda: Aysheaiidae) with chemical defenses from the Carboniferous

 Palaeocampa anthrax Meek & Worthen, 1865
A large (40 mm) Palaeocampa anthrax is depicted at the edge of a shallow inland streambed, shadowed by the lush vegetation and mist of a coal forest, flanked by several euthycarcinoids, Sottyxerxes multiplex116 (max size ~35 mm), and a pair of freshwater xiphosurans, Alanops magnificus (max size ~25 mm). The nearest ocean environment is several hundred kilometers southwest.

in Knecht, McCall, Tsai, Childers et Yu. 2025.  

DOI: doi.org/10.1038/s42003-025-08483-0 

 

Abstract

Lobopodians are an evolutionary grade of panarthropods characterized by their vermiform bodies and paired, unjointed lobopodous legs. A paraphyletic group, their study is of particular significance in understanding the evolution of extant panarthropods. Found exclusively in marine deposits from the Paleozoic, the great majority of species come from Cambrian Konservat-Lagerstätten, with only a few representatives known from the Ordovician, Silurian, and Carboniferous. Here we redescribe Palaeocampa anthrax from the Carboniferous Mazon Creek (USA) and Montceau-les-Mines (France) Lagerstätten as a lobopodian. First published in 1865, nearly fifty years before the discovery of the Burgess Shale, Palaeocampa is historically the first discovered lobopod, and its presence at the slightly younger Montceau-les-Mines (Gzhelian), makes this the youngest known fossil ‘xenusiid’ lobopodian species. We present the case that Palaeocampa most likely inhabited a freshwater environment, contesting the view that Paleozoic lobopodians were exclusively marine. Palaeocampa bears biomineralized dorso-lateral and lateral sclerite sets with a unique architecture unseen in other lobopodian sclerites, which may have been capable of secreting defensive chemicals at their tips. Palaeocampa anthrax represents a major evolutionary step in lobopodians, both in environmental adaptations and in defensive abilities.

Systematic Paleontology 

Panarthropoda Nielsen, 1995

Family Aysheaiidae Walcott, 1911

†Palaeocampa Meek & Worthen, 1865

Type species: Palaeocampa anthrax Meek & Worthen, 1865, by monotypy.

Environmental reconstruction of the Montceau-les-Mines Lagerstätte with Palaeocampa anthrax.
A large (40 mm) Palaeocampa anthrax is depicted at the edge of a shallow inland streambed, shadowed by the lush vegetation and mist of a coal forest, flanked by several euthycarcinoids, Sottyxerxes multiplex116 (max size ~35 mm), and a pair of freshwater xiphosurans, Alanops magnificus (max size ~25 mm). The nearest ocean environment is several hundred kilometers southwest.

 

Richard J. Knecht, Christian R. A. McCall, Cheng-Chia Tsai, Richard A. Rabideau Childers and Nanfang Yu. 2025. Palaeocampa anthrax, An armored freshwater Lobopodian with chemical defenses from the Carboniferous. Communications Biology. 8, 1080. DOI: doi.org/10.1038/s42003-025-08483-0 [23 July 2025]

https://x.com/Prehistorica_CM/status/1947947434832716068

  

[Paleontology • 2025] Primicaris larvaformis • A tiny Cambrian stem-mandibulate reveals Independent Evolution of Limb Ttagmatization and Specialization in early Euarthropods

Primicaris larvaformis  Zhang, Han, Zhang, Liu & Shu, 2003

in Liu, Zeng, Zhao, Y. Zhu, Li, Yin et M. Zhu, 2025. 

DOI: doi.org/10.1038/s41598-025-03544-0 

Abstract

The mandibulate euarthropods are the most speciose animal group, but the evolutionary gaps in origin of mandibulate body plan remain unresolved. Marrellomorphs, a common Paleozoic euarthropod group, had a long evolutionary history from Cambrian to Devonian. With computed microtomography, here we report the fine-scale soft-bodied morphoanatomy of the oldest marrellomorph Primicaris larvaformis, a millimeters-sized euarthropod from the ~ 518-million-year-old Chengjiang biota, China. Primicaris possesses a body plan featuring morphologically similar post-antennular biramous appendages, but also mandibulate diagnostic features including multi-segmented exopodites, a well-developed and differentiated hypostome-labrum complex, and a pancrustacean-like topological configuration of frontalmost three pairs of appendages. Phylogenetic analysis resolves Acercostraca and Marrellida as stem-Mandibulata. The undifferentiated post-antennular appendages in Primicaris suggest a possibility that the head appendages acquired a crown-mandibulate configuration before their morphological specialization in mandibulate origin. The emergence of novel appendage morphotypes in Acercostraca and Marrellida reveals that the complexity of limb tagmatization evolved independently in different Euarthropoda clades.

Keywords: Computed tomography, Limb tagmatization, Euarthropod, Mandibulate, Chengjiang biota, Cambrian explosion

Overall morphology of Primicaris larvaformis.
 (a) NIGP 200783A, optical photo, ventral view. (b, c) Juvenile specimens. (b) NIGP 200792, optical photo, ventral view. (c) NIGP 200791A, optical photo, dorsal view. (d, e) NIGP 200812 (see also in Fig. 3). (d) Optical photo, dorsal view. (e) Tomographic maximum projection image, dorsal view. (f) NIGP 200798A, optical photo, ventral view. (g) NIGP 200809A, optical photo, dorsal view. (h) NIGP 200810, optical photo, dorsal view. (i) NIGP 200813A, optical photo, ventral view. (j, k) NIGP 200799. (j) Optical photo, dorsal view. (k) SEM-EDS map of carbon. (i, m) NIGP 200817. (l) Optical photo, dorsal view. (m) SEM-EDS map of iron.

 a1–14, post-antennular appendage 1–14; ab, anterior border; an, antennule; ax, axial region; ba, base of appendage; dv, gut diverticulae; eb, eye bulge; er, eye ridge; gt, gut; ls1–11, lateral spine of dorsal shield 1–11; pl, pleural region; ps, posterior spine of dorsal shield; rg, ridge of dorsal shield; st, setae. 

Scale bars represent: 0.5 mm (a–m).

Systematic palaeontology

Phylum Euarthropoda Lankaster, 1904.

Order Acercostraca Lehmann, 1955.

Genus Primicaris Zhang, Han, Zhang, Liu and Shu, 2003

Primicaris larvaformis Zhang, Han, Zhang, Liu and Shu, 2003

Emended diagnosis: Small euarthropod with a body length less than 6 mm. Undivided dorsal shield with up to twelve pairs of lateral marginal spines and a pair of posterior spines. One pair of uniramous antennules is followed by up to 14 homonomous pairs of biramous appendages (emended from ref. 13).

 

Yao Liu, Han Zeng, Fangchen Zhao, Yuyan Zhu, Yimeng Li, Zongjun Yin and Maoyan Zhu. 2025. A tiny Cambrian stem-mandibulate reveals Independent Evolution of Limb Ttagmatization and Specialization in early Euarthropods. Scientific Reports. 15: 19115. DOI: doi.org/10.1038/s41598-025-03544-0 [31 May 2025]