[Paleontology • 2026] Paleocanna tentaculum • Thecate stem medusozoan polyp (Cnidaria: Anthozoa) from the Upper Ordovician of Québec, Canada

  

Paleocanna tentaculum  

 Ramirez-Guerrero, Alghaled, Bateman, Cournoyer & Cameron, 2026

 

 DOI: doi.org/10.1017/jpa.2025.10211

 

Abstract

The fossil record of medusozoan cnidarians is relatively sparse and, in some cases, contentious. Here, we describe a new genus and species of a well-preserved, soft-bodied, tubicolous polyp, Paleocanna tentaculum n. gen. n. sp., from the Upper Ordovician (Katian) Neuville Formation in Québec. These fossils, preserved as carbonaceous compressions, were found in association with typical shelly assemblages. Fifteen slabs of shaly limestone containing ~ 135 specimens of Paleocanna tentaculum n. gen. n. sp. were examined. Individual polyps occupied upright tubes, which occur either solitarily or in clusters. Some tubes exhibit a striated periderm near their base. The polyp is elongated, with a rounded aboral end and a consistent ring of tentacles protruding distally from the tube. A phylogenetic analysis of 69 taxa and 236 discrete morphological characters indicated that the species is more closely related to the extant crown group than it is to the other stem-group medusozoans, e.g., conulariids and carinachitids. The uniform orientation of specimens on single slabs suggests rapid burial. Paleocanna tentaculum n. gen. n. sp. represents an exceptionally preserved member of an Ordovician deposit exhibiting Burgess Shale-type soft-tissue preservation.

Paleocanna tentaculum n. gen. n. sp., holotype, MPEP713.4.
 (1) General view of the organism taken under cross-polarized light; accompanying line drawing illustrates the outline of the tube and tentacles. (2) Detail of the left set of tentacles. (3) Detail of the basal part of the tube. (4) Detail of the tube. Scale bars = 1 cm (1, 3), 0.5 cm (2, 4).

Systematic paleontology

Phylum Cnidaria Verrill, Reference Verrill1865

Subphylum Anthozoa Ehrenberg, Reference Ehrenberg1834

Genus Paleocanna new genus

Etymology: Paleocanna: palaios, meaning old or ancient, plus canna, meaning flute or pipe.

 Paleocanna tentaculum new species

Diagnosis: Cylindrical tubicolous periderm with fine, parallel, transverse annulations; polyp with anterior tentacle crown extending from aperture.

Occurrence: Upper Neuville Formation of the Saint Lawrence Lowlands of Québec, Canada (Clark, Reference Clark1959).

 Interpretive drawings of Paleocanna tentaculum n. gen. n. sp. as living organisms.
(1) Oral view showing a circle of tentacles. (2) Lateral perspective of the tube, highlighting the tube aperture and annular striations. (3) Depiction of individuals living in single tubes, as well as clusters of two or three tubes attached together.

Greta Ramirez-Guerrero, Huda Alghaled, Louis-Philippe Bateman, Mario Cournoyer and Christopher B. Cameron. 2026. Thecate stem medusozoan polyp from the Upper Ordovician of Québec. Journal of Paleontology. First View. DOI: doi.org/10.1017/jpa.2025.10211 [13 February 2026]

[Paleontology • 2026] Tyrannoroter heberti • Carboniferous recumbirostran elucidates the origins of terrestrial herbivory

Tyrannoroter heberti 

Mann, Xiong, Calthorpe, Sues & Maddin, 2026

 

DOI: doi.org/10.1038/s41559-025-02929-8

Abstract

The evolution of herbivory is one of the most important ecological events in the evolution of terrestrial vertebrates and impacted the ecosystems they inhabited. Herbivory independently developed in a number of tetrapod clades during the Late Carboniferous and Permian, eventually leading to the establishment of the basic structure of modern terrestrial ecosystems. Here we describe a Late Carboniferous pantylid ‘microsaur’, Tyrannoroter heberti gen. et sp. nov., with expansive occluding palatal and coronoid dental batteries. The shape of the teeth, as revealed by high-resolution micro-computed tomography data, indicates wear from both shearing and grinding motions consistent with herbivory. New data from historical pantylid fossils show that similar adaptations can be traced back as far as the Bashkirian (~318 million years ago), indicating that terrestrial herbivory was already widespread within this group, and originated rapidly following the terrestrialization of tetrapods. The placement of recumbirostran ‘microsaurs’ on the amniote stem suggests that terrestrial herbivory is not an amniote innovation, although the phylogenetic position of ‘microsaurian’ tetrapods remains uncertain. Under any phylogenetic scenario, the data presented here reveal that pantylids acquired adaptations to herbivory independently, probably via durophagous omnivory, feeding on insects, shelled animals and tough plant material.

Tyrannoroter heberti gen. et sp. nov.

Arjan Mann, Zifang Xiong, Ami S. Calthorpe, Hans-Dieter Sues and Hillary C. Maddin. 2026. Carboniferous recumbirostran elucidates the origins of terrestrial herbivory. Nature Ecology & Evolution. 10; 193–202. DOI: doi.org/10.1038/s41559-025-02929-8 [10 February 2026]

[PaleoEntomology • 2025] Cordualadensa acorni • New Family of Fossil Dragonfly (Odonata: Cavilabiata) from the late Cretaceous (Campanian) Dinosaur Park Formation, Alberta, Canada

Cordualadensa acorni

Mueller, Demers-Potvin & Larsson, 2025 

  

DOI: doi.org/10.1139/cjes-2024-0162  

Abstract

A new dragonfly species, Cordualadensa acorni gen. et sp. nov., assigned to Cordualadensidae fam. nov. (Odonata, Cavilabiata), is described from Dinosaur Provincial Park (DPP). The taxon represents the oldest known North American fossil taxon within Cavilabiata and the only Mesozoic dragonfly for Canada. This discovery provides a missing link in the evolutionary transition from the early Cretaceous Cavilabiata to extant families and introduces one of the few dragonflies known from the late Cretaceous fossil record. The specimen described herein also confirms that insect impression fossils can be preserved in the Dinosaur Park Formation (DPF) and suggests that the diversity of the entomofauna preserved in DPP's fossil assemblage is only beginning to be fully appreciated. The presence of dragonflies in the DPF also supports the hypothesis that Campanian Alberta had a sufficiently high insect biomass to support insect predators at higher trophic levels.

Cordualadensa acorni gen. et sp. nov.

 

 André S. Mueller, Alexandre V. Demers-Potvin and Hans C.E. Larsson. 2025. New Family of Fossil Dragonfly (Odonata, Cavilabiata) from the late Cretaceous (Campanian) Dinosaur Park Formation, Alberta, Canada. Canadian Journal of Earth Sciences. 62(8): 1373-1381. DOI: doi.org/10.1139/cjes-2024-0162  [1 August 2025]

https://www.mcgill.ca/newsroom/channels/news/mcgill-team-discovers-canadas-first-dinosaur-era-dragonfly-fossil-366386

[PaleoIchthyology • 2025] Sphyragnathus tyche • A New predatory Actinopterygian from the Tournaisian of Nova Scotia provides insight into the Evolution of Actinopterygian Feeding

 

Sphyragnathus tyche

Wilson, Mansky & Anderson, 2025

 DOI: doi.org/10.1080/02724634.2025.2498453

ABSTRACT

The Devonian–Carboniferous transition represents a fundamental shift in vertebrate faunal composition and ocean ecology. Tournaisian-aged outcrops of the Horton Bluff Formation from Blue Beach, Nova Scotia capture this moment and yield a diverse fauna of actinopterygians and other vertebrates. Here, we report an actinopterygian mandible preserved in 3D, representing a new genus and species, Sphyragnathus tyche. This mandible is elongate, deeply curved, and bears a primary dentition of heterodont fangs. Actinopterygian identity is established by the characteristic ornamentation, dentition, and overall mandible construction observed in the specimen. Analysis of the relationship between mandible and body length in Paleozoic actinopterygians establishes S. tyche as a relatively large actinopterygian. Mandible length, curvature, and fang morphology combine to produce a functionally differentiated dentition with distinct regions for prey capture and prey processing. Comparison with modern actinopterygians places S. tyche as a back-fanged macrodont, distinguishing it from front-fanged macrodont actinopterygians of the Late Devonian. This earliest known instance of back-fanged macrodonty in the actinopterygian fossil record provides further evidence of actinopterygian morphological differentiation post-Devonian and implies experimentation in feeding mode. Apparent changes in feeding mode are underscored by analysis of stress distribution across the dentition of Devonian front-fanged macrodont actinopterygians and S. tyche. Although this specimen is compatible with a previous ‘head-first’ model of morphological diversification in early Carboniferous actinopterygians, we argue that a ‘feeding-first’ model is a better fit.

 

  Sphyragnathus tyche sp. nov. 

Conrad D. Wilson, Chris F. Mansky and Jason S. Anderson. 2025. A New predatory Actinopterygian from the Tournaisian of Nova Scotia provides insight into the Evolution of Actinopterygian Feeding. Journal of Vertebrate Paleontology. e2498453. DOI: doi.org/10.1080/02724634.2025.2498453  [18 Jun 2025]

[Invertebrate • 2024] Synallactes mcdanieli • A New Species of Sea Cucumber (Holothuroidea: Synallactida) from British Columbia, Canada and the Gulf of Alaska, USA

Synallactes mcdanieli 

Marín, Ochoa & Conejeros-Vargas, 2024

DOI: doi.org/10.3897/BDJ.12.e124603

Abstract

Background: The family Synallactidae comprises mostly deep-sea forms and is the least-studied large taxon amongst deep-sea cucumbers. They are part of the abyssal megafauna and play an important role in modifying the sediment landscape and structuring the communities that live within it. The family embraces the genus Synallactes, which contains approximately twenty-five species from the Pacific, Atlantic (six species), Indian (seven species) and Antarctic Oceans (one species).

New information: Synallactes mcdanieli sp. nov. is described from the Northeast Pacific, Knight Inlet, British Columbia, Canada to Kodiak Island, Gulf of Alaska, USA, at depths from 21 to 438 m. This new species is unique amongst the species of the genus Synallactes because of the number and arrangement of dorsal papillae, number of Polian vesicles, together with the entire ossicle arrangement. In addition, this species has the shallowest bathymetric distribution ever recorded for this genus.

Keywords: Synallactidae, taxonomy, Northeast Pacific

Synallactes mcdanieli sp. nov. In situ specimens at Battery Point, near Haines Alaska, USA, photo by Neil McDaniel. Approximately TL of specimens ~ 250-300 mm.

 

 Francisco A Solís Marín, Andrea A Caballero Ochoa and Carlos A Conejeros-Vargas. 2024. Synallactes mcdanieli sp. nov., A New Species of Sea Cucumber from British Columbia, Canada and the Gulf of Alaska, USA (Holothuroidea, Synallactida). Biodiversity Data Journal. 12: e124603. DOI: doi.org/10.3897/BDJ.12.e124603

[Paleontology • 2025] Traskasaura sandrae • A Name for the Provincial Fossil of British Columbia: A Strange New elasmosaur Taxon from the Santonian of Vancouver Island

 

Traskasaura sandrae

O’Keefe, Smith, Clark, Otero, Perella & Trask, 2025

DOI: doi.org/10.1080/14772019.2025.2489938 

Abstract

The first elasmosaurid skeleton from the Haslam Formation (Upper Santonian) of the Nanaimo Group (Late Cretaceous) on Vancouver Island was first described in 2002, and has recently been declared the Provincial Fossil of British Columbia. Since then, additional fossils have been recovered: an isolated right humerus and a well-preserved, osteologically immature skeleton comprising thorax, girdles and limbs. The Haslam material can now support further taxonomic assessment, and we erect the species Traskasaura sandrae based on it. Traskasaura possesses a strange mosaic of features. The mandible is plesiomorphic as seen in Libonectes: relatively narrow with large teeth and a broad symphysis. The skull therefore lacks any of the radical oral cavity adaptations seen in basal aristonectines. The neck of the Haslam animal is also plesiomorphic, with at least 36 preserved cervical vertebrae having vertebral length indices (VLIs) over 100 (the total number of cervicals is not known). The centra lack the anteroposterior compression and midline longitudinal constriction characteristic of derived aristonectines, yet the cervical ribs trend forward – a condition known only in derived aristonectines and Vegasaurus. The autapomorphic coracoid of Traskasaura differs greatly from any known elasmosaurid; the cardiform recess is reduced and posteriorly located, with some similarities to that of Aristonectes quiriquinensis. The humerus is autapomorphic, possessing a relatively straight shaft, pronounced ventral camber and an articular facet on the leading edge that makes a 90° angle with the radial facet. Taken together, these features document a new genus, with a plesiomorphic axial skeleton, but with several convergent appendicular adaptations with derived aristonectines. A revised phylogenetic analysis of Elasmosauridae recovered the new taxon in a basal position. Therefore, the postcranial adaptations shared with derived aristonectines appear to be convergent.

Keywords: elasmosaur, Haslam Formation, plesiosaur, Santonian

Sauropterygia Owen, Citation1860

Order Plesiosauria de Blainville, Citation1835

Family Elasmosauridae Cope, Citation1869

Traskasaura sandrae gen. et sp. nov.

Etymology: The genus is named in honour of Michael and Heather Trask, who discovered the holotype specimen along the banks of the Puntledge river in 1988, and the Greek word saûros, lizard; the Latin conjugation is feminine. The species name sandrae honours Sandra Lee O’Keefe (née Markey), Pacific Northwest native and, like Elizabeth Nicholls, a valiant warrior in the fight against breast cancer. In loving memory.

F. Robin O’Keefe, Elliott Armour Smith, Robert O. Clark, Rodrigo A. Otero, Anna Perella and Patrick Trask. 2025. A Name for the Provincial Fossil of British Columbia: A Strange New elasmosaur Taxon from the Santonian of Vancouver Island. Journal of Systematic Palaeontology. 23(1); 2489938. DOI: doi.org/10.1080/14772019.2025.2489938 [22 May 2025] 

[Paleontology • 2025] Mosura fentoni • Early Evolvability in Arthropod Tagmosis exemplified by A New Radiodont from the Burgess Shale

 

Mosura fentoni 

 Moysiuk & Caron, 2025

  

DOI: doi.org/10.1098/rsos.242122 

Abstract

Much diversity in arthropod form is the result of variation in the number and differentiation of segments (tagmosis). Fossil evidence to date has suggested that the earliest-diverging arthropods, the radiodonts, exhibited comparatively limited variability in tagmosis. We present a new radiodont, Mosura fentoni n. gen. and n. sp., from the Cambrian (Wuliuan) Burgess Shale that departs from this pattern. Mosura exhibits up to 26 trunk segments, the highest number reported for any radiodont, despite being among the smallest known. The head is short, with a small, rounded preocular sclerite, three prominent eyes and appendages with curving endites tipped with paired spines, altogether suggesting a nektonic, macrophagous predatory ecology. The trunk is divided into a neck, mesotrunk with large swimming flaps and multisegmented posterotrunk with tightly spaced bands of gill lamellae and reduced flaps. Detailed preservation of expansive circulatory lacunae, closely associated with the gills, clarifies the nature of similar structures in other Cambrian arthropod fossils, including Opabinia. The morphology of the posterotrunk suggests specialization for respiration, unique among radiodonts, but broadly convergent with the xiphosuran opisthosoma, isopod pleon and hexapod abdomen. This reinforces the hypothesis that multiple arthropod lineages underwent parallel diversification in tagmosis, in tandem with their initial Cambrian radiation.

Keywords: segmentation, convergence, Cambrian explosion, functional specialization, body plan, arthropod

Systematic palaeontology

 

Superphylum Panarthropoda Nielsen 1995 

Phylum Arthropoda Gravenhorst 1843

Order Radiodonta Collins 1996 

Family Hurdiidae Lerosey-Aubril & Pates 2018 

Genus Mosura n. gen.

Type species: M. fentoni n. sp., by monotypy.

Etymology: From the name of the fictional Japanese monster, or kaiju モスラ (also known as ‘Mothra’), romanized according to Hepburn style, in reference to the moth-like appearance of the animal.

 Morphological summary and artistic reconstruction.
 (a) Life reconstruction; (b) whole body, dorsal view; (c) ventral view; (d) cross-section through mesotrunk;
(e) appendage, lateral view; (f) appendage, frontal view; (g) podomere 5 from lateral and frontal views; (h) appendage, ventral view, extended; (i) appendage, ventral view, retracted.

 Abbreviations: bf, bifurcated tip of endite; br, brain; en, endite; fa, frontal appendage; fg, foregut; fl, flap; fn, frontal appendage nerve/circulatory lacuna; ip, putative inner plates of oral cone; lc, lacuna of circulatory system; le, lateral eye; lm, band of lamellae; me, median eye; mg, midgut; mo, mouth; mt, mesotrunk; ne, neck; np#, lateral eye neuropil #; oc, oral cone; on, optic nerve; os, preocular sclerite; ot, outer spine of appendage; p, phosphatized element; pd#, podomere #; pt, posterotrunk; ra, flap ray; sb, segmental boundary; tp, terminal process; ts, terminal spine of appendage. Elements shown in dashed lines (appendage podomeres, oral plates, ring-shaped brain) are uncertain and have been inferred.

Artwork by Danielle Dufault © Royal Ontario Museum.

 

Mosura fentoni n. sp.

 

Holotype: ROMIP 67995, part and counterpart, a complete specimen preserved in dorsal view (figure 2a–d).

Etymology: In honour of Peter E. Fenton, for his 40 years of service as a technician in the Invertebrate Palaeontology section at the Royal Ontario Museum, and for his unwavering friendship to both authors.

Diagnosis: Radiodont with an adult trunk region divided into a four-segmented neck, six-segmented mesotrunk and up to 16-segmented posterotrunk. Flaps of mesotrunk up to ca 60% of core segment width. Flaps of posterotrunk markedly differentiated in size, less than ca 20% of core segment width. Caudal blades absent, posterotrunk terminating in pair of small, triangular processes. Appendages with six elongate endites (ca 3.5 times podomere height) with bifurcated tips. Lateral eye stalks short, less than eye diameter.

Joseph Moysiuk and Jean-Bernard Caron. 2025. Early Evolvability in Arthropod Tagmosis exemplified by A New Radiodont from the Burgess Shale. R. Soc. Open Sci. 12: 242122. DOI: doi.org/10.1098/rsos.242122 [14 May 2025]

 

[Paleontology • 2025] Helmetia expansa Walcott, 1918 Revisited – New insights into the internal anatomy, moulting and phylogeny of Conciliterga

Helmetia expansa Walcott, 1918 

in Losso, Caron et Ortega-Hernández, 2025. 

DOI: doi.org/10.1080/14772019.2025.2468195 

 Reconstruction by Marianne Collins

Abstract

The trilobitomorphs are a megadiverse and ecologically versatile group of Paleozoic euarthropods that include the iconic trilobites, as well as non-biomineralized clades exclusively known from Konservat-Lagersttätten. The concilitergans, defined by the presence of a broad, variably effaced and flattened dorsal exoskeleton, have received comparatively little attention. This is particularly true for Helmetia expansa from the mid-Cambrian Burgess Shale (British Columbia) – the first chronologically reported species of Conciliterga, which was originally figured (based on a single specimen) by Walcott (1918). Here, we present the first comprehensive description of H. expansa based on all material available from the Burgess Shale, totalling 36 specimens housed at the Royal Ontario Museum and the Smithsonian Institution. The non-biomineralized dorsal exoskeleton is broad and flat, with a serrated margin throughout. The body consists of a cephalon with well-developed anterolateral spines, six thoracic tergites and a large pygidium bearing two pairs of lateral spines and a single terminal spine. The preserved appendages include short uniramous antennae followed by 15 pairs of homonomous and biramous limbs composed of a gracile endopodite and an exopodite with a broad lobe and thick lamellae. The digestive system consists of a straight gut tract, including a ‘J’-shaped foregut and five paired digestive glands on the anterior half of the body expressed as small and convex oblong structures with a submillimetric lamellar ultrastructure. Two specimens of H. expansa provide the first direct evidence of moulting in concilitergans. The lack of dorsal ecdysial sutures suggests a marginal moulting strategy similar to extant Xiphosura. A revised phylogeny of Trilobitomorpha supports Arthroaspis bergstroemi from the early Cambrian Sirius Passet of Greenland as the earliest branching concilitergan and prompts a new diagnosis for the clade. Our results inform the internal relationships within Conciliterga and formalize the families Helmetiidae (Helmetia, Rhombicalvaria, Haifengella and Kuamaia) and Tegopeltidae (Tegopelte, Skioldia, Saperion).

Keywords: Burgess Shale, Cambrian, Conciliterga, exceptional preservation, Helmetiida, moulting

Artiopoda Hou & Bergström, 1997

Trilobitomorpha Størmer, 1944

Conciliterga Hou & Bergström, 1997

Constituent taxa: Arthroaspis bergstroemi Stein et al., 2013; Helmetiida Novozhilov, 1960.

Order Helmetiida Novozhilov, 1960

Constituent taxa: Family Tegopeltidae Simonetta & Delle Cave, 1975; Family Helmetiidae Simonetta & Delle Cave, 1975.

Concilitergan diversity and relationships.
A, Arthroaspis bergstroemi, MGUH 30382, from the early Cambrian (Stage 3) Sirius Passet, Greenland. B, Helmetia expansa, USNM 83952, from the mid-Cambrian (Wuliuan) Burgess Shale, Canada. C, Kuamaia lata, CJHMD 00064, from early Cambrian (Stage 3) Chengjiang, China. D, Tegopelte gigas, USNM 189201, from the mid-Cambrian (Wuliuan) Burgess Shale, Canada.
E, simplified topology based on results from phylogenetic analyses herein which resolved Arthroaspis bergstroemi as an early-branching concilitergan.

 Holotype of Helmetia expansa USNM 83952, dorsal view.
A, Cross polarized light. B, Low angle light. C, Magnification of A showing cephalon. D, Magnification of A showing lamellae.

Abbreviations: cep, cephalon; anl, anterolateral spine; ant, antenna; asc, anterior sclerite; ey, eye; ex, exopodite; hyp, hypostome; lm, lamellae; mey, medial eyes; mg, midgut gland; opn, optical nerve; py, pygidium; rs, reniform structure; stn, sternite number; th, thorax.

Family Tegopeltidae Simonetta & Delle Cave, 1975

Constituent genera: Tegopelte Simonetta & Delle Cave, 1975; Skioldia Hou & Bergström, 1997; and Saperion Hou & Bergström, 1997.

...

Family Helmetiidae Simonetta & Delle Cave, 1975

Emended diagnosis: Concilitergans in which the thorax has tergites with non-effaced boundaries and well-developed pleural spines, and a pygidium with variable number of posterolateral spines and a medial terminal spine with a broad base.

Constituent genera: Helmetia Walcott, 1918; Rhombicalvaria Hou, 1987; Haifengella Zhao et al., 2014; Kuamaia Hou & Bergström, 1997.

Genus Helmetia Walcott, 1918

Type species: Helmetia expansa Walcott, 1918

 

 the Burgess Shale concilitergan Helmetia expansa.

 Reconstruction by Marianne Collins

Conclusion: 

We redescribe Helmetia expansa as one of the best-known concilitergans based on 36 specimens from the Burgess Shale. It has large anterolateral spines, a serrated margin, a six-segmented thorax and a large pygidium with two pairs of spines.

New material reveals insights into the preservation of non-biomineralized structures in H. expansa, including antennae, biramous appendages, optic structures and traces of digestive glands. Additionally, H. expansa acquired an adult exoskeletal morphology that at least doubled in size throughout ontogeny and provides rare direct evidence of moulting in a non-biomineralized Cambrian trilobitomorph.

New morphological characters and broader taxon sampling of Cambrian artiopodans clarifies the internal relationships within Conciliterga, which contains Arthroaspis bergstroemi from Sirius Passet and two major families Helmetiidae and Tegopeltidae, both represented in the Burgess Shale and Chengjiang Lagerstätten.

Sarah R. Losso, Jean-Bernard Caron and Javier Ortega-Hernández. 2025. Helmetia expansa Walcott, 1918 Revisited – New insights into the internal anatomy, moulting and phylogeny of Conciliterga. Journal of Systematic Palaeontology. 23(1); 2468195. DOI: doi.org/10.1080/14772019.2025.2468195  [04 Apr 2025]

 

[Entomology • 2025] Papilio solstitius • A cryptic New Species of Tiger Swallowtail (Lepidoptera: Papilionidae) from eastern North America

Papilio solstitius  

DeRoller, Wang, Dupuis & Schmidt, 2025 

DOI: doi.org/10.3897/zookeys.1228.142202

 

Abstract

In the eastern Great Lakes region of North America, two tiger swallowtail species have previously been recognized, Papilio glaucus Linnaeus, 1758 and Papilio canadensis Rothschild & Jordan, 1906. A third entity, the Midsummer Tiger Swallowtail, has been treated as a P. glaucus × canadensis hybrid, and exhibits a mosaic of both intermediate and unique morphological and biological traits. Here we demonstrate that rather than being a localized, historically recent hybrid phenomenon, the Midsummer Tiger Swallowtail maintains its morphological and physiological distinctness over a large geographic region in the absence of one or both putative parental species, and was first documented in the literature nearly 150 years ago. Papilio solstitius sp. nov. is physiologically unique in delaying post-diapause development, which results in allochronic isolation between the spring flights of P. glaucus and P. canadensis, and the late summer flight of P. glaucus. Similarly, the geographic range of Papilio solstitius spans the region between the northern terminus of P. glaucus and southern limits of P. canadensis, remaining distinct in areas of sympatry. Defining the taxonomic identity of this unique evolutionary lineage provides an important baseline for further inquiry into what has served as an exemplary species group in evolutionary study.

Key words: cryptic species, hybrid, Papilio glaucus, Papilionidae, Pterourus, speciation

Papilio solstitius
a dorsum of male, holotype, ventrum on right. Long Swamp, Old Almonte Rd., Ottawa, Ontario, CAN. CNC voucher # CNCLEP00342771
b dorsum of female allotype, ventrum on right. Vanalstine Lake, Frontenac Co., Ontario, CAN; ovipositing on Prunus serotina.

Scale bar:10 mm.

 Papilio solstitius sp. nov.

Etymology: The epithet solstitius is derived from solstitium, the Latin term for solstice. The species’ unique midsummer flight period commences near the summer solstice.

Differential diagnosis. Papilio solstitius is closely related to P. glaucus, P. canadensis and P. appalachiensis, but differs from all in a suite of characters (Table 1). The most significant differences are apparent in developmental biology and phenology. Papilio solstitius is unique in its long post-diapause emergence delay, with adult eclosion beginning in late June to early July, compared to May for all other species (Fig. 2). Unlike the facultatively multivoltine P. glaucus, P. solstitius is obligately univoltine (like P. canadensis and P. appalachiensis). In the northern part of its range, P. solstitius overlaps with P. canadensis, and in the south with P. glaucus; it is not known to overlap with P. appalachiensis (Fig. 1). Identification difficulties are therefore largely limited to confusion with either P. canadensis or P. glaucus. In combination with location and date, the comparative morphological characters summarized in Table 1 and discussed in the “Comparative Morphology” section below will serve to identify most specimens.

 

Charles J. DeRoller, Xi Wang, Julian R. Dupuis, B. Christian Schmidt. 2025. A cryptic New Species of Tiger Swallowtail (Lepidoptera, Papilionidae) from eastern North America. ZooKeys. 1228: 69-97. DOI: doi.org/10.3897/zookeys.1228.142202

[Paleontology • 2024] Entothyreos synnaustrus • Deep Origin of Articulation Strategies in Panarthropods: Evidence from A New luolishaniid Lobopodian (Panarthropoda) from the Tulip Beds, Burgess Shale

Entothyreos synnaustrus 

Aria & Caron, 2024  

DOI: 10.1080/14772019.2024.2356090 

Artwork by Danielle Dufault x.com/MesozoicMuse

Abstract

The evolution of articulated sclerites via soft membranes, termed arthrodization, is arguably one of the most critical innovations in animals. Defining the megaphylum Arthropoda, the arthrodization of appendages, or arthropodization, likely predated that of the body, the combination of both being diagnostic of true arthropods (Euarthropoda) – all of these innovations occurring during the Cambrian explosion. Here, thanks to dozens of exceptionally preserved fossils from the Cambrian Wuliuan Stage Burgess Shale (Tulip Beds locality on Mount Stephen, British Columbia, Canada), we show that a distinct but comparable system of imbricated sclerotic elements evolved in the paraphyletic sister group of arthropods, the lobopodians. Entothyreos synnaustrus gen. et sp. nov. has characteristic body plan features of the Collinsovermidae (order Luolishaniida), including anterior limbs for suspension-feeding and stout anchoring posterior limbs. Uniquely, however, E. synnaustrus also displays segmental sclerotic sheets along the trunk, covered in a thin layer of integument, as well as overlapping sclerotized annuli on posterior-most limbs. While the latter elements likely served a protective function, the dorsolateral trunk sheets, which also carry spines, may have facilitated body erection and suspension-feeding. Other luolishaniids possess separate ring-like structures connecting the base of metameric spines which are covered by the apical layer of the lobopodian integument. E. synnaustrus and related taxa illustrate, therefore, an arguably parallel evolution of arthropod-like morphoanatomical features early during the rise of panarthropods. This finding broadens our perspectives on the uniqueness of major synapomorphies and the importance of including canalization in macroevolutionary narratives.

Keywords: Cambrian, Burgess Shale, Panarthropoda, lobopodian, arthrodization, convergence

Entothyreos synnaustrus gen. et sp. nov. 

 

Cédric Aria and Jean-Bernard Caron. 2024. Deep Origin of Articulation Strategies in Panarthropods: Evidence from A New luolishaniid Lobopodian (Panarthropoda) from the Tulip Beds, Burgess Shale. Journal of Systematic Palaeontology. 22(1); 2356090. DOI: 10.1080/14772019.2024.2356090

 x.com/MesozoicMuse/status/1804256832837300241

[Invertebrate • 2023] Xyloplax princealberti (Echinodermata: Asteroidea) • A New Species that is not always associated with Wood Falls

Xyloplax princealberti 

Payne, Tilic, Boschen-Rose, Gannon, Stiller, Hiley, Grupe, Mah & Rouse, 2023

DOI: 10.3390/d15121212 

 twitter.com/_Cheyenne_Payne 

Abstract

Xyloplax is a genus of three species of sea stars previously found only on sunken wood in the deep ocean. Their circular and petaloid bodies, which lend them their common name “sea daisy”, and their presumed exclusive diet of wood make them an unusual and rare element of deep-sea ecosystems. We describe here the fourth species of Xyloplax from the eastern Pacific Ocean, Xyloplax princealberti n. sp., which ranges from offshore Canada to the Gulf of California (Mexico) and Costa Rica. Though sampled geographically close to another described species of Xyloplax from the northeastern Pacific, X. janetae, this new species is unique morphologically and according to available DNA data. The short abactinal spines are the most obvious feature that distinguishes X. princealberti n. sp. from other Xyloplax. The minimum distance for mitochondrial cytochrome c oxidase subunit I from Xyloplax princealberti n. sp. to the only other available Xyloplax, X. janetae, was 13.5%. We also describe Ridgeia vestimentiferan tubeworm bushes from active hydrothermal vents as a new Xyloplax habitat, the first record of a non-wood substrate, and a new reproductive strategy, simultaneous hermaphroditism, for this genus. We generated the first mitochondrial genome for a member of Xyloplax and analyzed it with other available asteroid data using nucleotide-coding or amino acid (for protein-coding genes) plus nucleotide coding (for rRNA genes). The nucleotide-coding results place Xylopax as part of the clade Velatida, consistent with a previous phylogenomic analysis that included Xyloplax princealberti n. sp. (as Xyloplax sp.), though the placement of Velatida within Asteroidea differed. The amino acid plus nucleotide coding recovered Velatida to be a grade with X. princealberti n. sp. as sister group to all other Asteroidea.

Keywords: deep sea; asteroid; hydrothermal vent

 Collection sites and representative individuals of Xyloplax princealberti n. sp.
 (A) Recovered wood block from Juan de Fuca Ridge, offshore Canada, showing a specimen on the surface (indicated with white arrow). Inset shows an animal in situ on the wood surface. (B) Ridgeia vestimentiferan bush sampled at the Juan de Fuca Ridge, offshore Canada. (C) Wood found with seven specimens of Xyloplax princealberti n. sp. at 2421 m on the Alarcón Rise, Gulf of California, Mexico. (D) Wood deployment at 1845 m at Jaco Scar, offshore Costa Rica. (E) Specimens in abactinal view collected from wood deployment in the Juan de Fuca Ridge, offshore Canada. (F) Specimens in abactinal view collected from wood in the Gulf of California, Mexico. (G) Two specimens in abactinal view from Jaco Scar, offshore Costa Rica. (H) Two specimens in actinal view from Jaco Scar, offshore Costa Rica.

 Images of Xyloplax princealberti n. sp. from the wood deployment in Juan de Fuca Ridge, offshore Canada.
(A) Live specimen (from lot SIO-BIC E6809), abactinal view. * indicates hydropore. (B) Live specimen (lot SIO-BIC E6809), actinal view. (C) Closeup of the abactinal view of a live specimen (lot SIO-BIC E6809), showing adambulacral spines and short abactinal spinelets. * indicates hydropore. (D) Closeup of the actinal view of a live specimen (lot SIO-BIC E6809), showing tube feet and adambulacral spines. (E) Preserved holotype (SIO-BIC E11463), abactinal view. (F) Preserved holotype (SIO-BIC E11463), actinal view. (G) Preserved holotype (SIO-BIC E11463), closeup ambulacral area showing 7 tube feet and abactinal spinelets, abactinal view.

VELATIDA

XYLOPLACIDAE Baker, Rowe & Clark, 1986 

Xyloplax Baker, Rowe & Clark, 1986 

 

Xyloplax princealberti n. sp.

Diagnosis: Xyloplax with rounded abactinal spine bases, spines uniformly short. Two to three adambulacral spines per plate; more than 100 total spines around margin. Tube feet rounded, bulbous, up to ten per segment. Terminal plates badge-shaped. Mouth, gut, and anus absent. “Viviparous”, simultaneous hermaphrodite.

Etymology: This species honors His Serene Highness Prince Albert II of Monaco for his efforts to protect the marine environment through the Prince Albert II of Monaco Foundation.

  Cheyenne Y. Payne, Ekin Tilic, Rachel E. Boschen-Rose, Amanda Gannon, Josefin Stiller, Avery S. Hiley, Benjamin M. Grupe, Christopher L. Mah and Greg W. Rouse. 2023. Xyloplax princealberti (Asteroidea, Echinodermata): A New Species that is not always associated with Wood Falls. Diversity. 15(12), 1212. DOI: 10.3390/d15121212

(This article belongs to the Special Issue Diversity and Biogeography of Sea Stars (Echinodermata, Asteroidea))

  twitter.com/_Cheyenne_Payne/status/1744505443982991665

[Paleontology • 2023] Burgessomedusa phasmiformis • A Macroscopic Free-swimming Medusa (Cnidaria: Medusozoa) from the middle Cambrian Burgess Shale

Burgessomedusa phasmiformis

Moon, Caron & Moysiuk, 2023

 DOI: 10.1098/rspb.2022.2490

Artwork by C. McCall.

Abstract

Cnidarians are regarded as one of the earliest-diverging animal phyla. One of the hallmarks of the cnidarian body plan is the evolution of a free-swimming medusa in some medusozoan classes, but the origin of this innovation remains poorly constrained by the fossil record and molecular data. Previously described macrofossils, putatively representing medusa stages of crown-group medusozoans from the Cambrian of Utah and South China, are here reinterpreted as ctenophore-grade organisms. Other putative Ediacaran to Cambrian medusozoan fossils consist mainly of microfossils and tubular forms. Here we describe Burgessomedusa phasmiformis gen. et sp. nov., the oldest unequivocal macroscopic free-swimming medusa in the fossil record. Our study is based on 182 exceptionally preserved body fossils from the middle Cambrian Burgess Shale (Raymond Quarry, British Columbia, Canada). Burgessomedusa possesses a cuboidal umbrella up to 20 cm high and over 90 short, finger-like tentacles. Phylogenetic analysis supports a medusozoan affinity, most likely as a stem group to Cubozoa or Acraspeda (a group including Staurozoa, Cubozoa and Scyphozoa). Burgessomedusa demonstrates an ancient origin for the free-swimming medusa life stage and supports a growing number of studies showing an early evolutionary diversification of Medusozoa, including of the crown group, during the late Precambrian–Cambrian transition.

Keywords: cnidarian, cambrian explosion, medusae

 

Systematic palaeontology

 Phylum Cnidaria Verrill, 1865

 Subphylum Medusozoa Peterson, 1979

 Burgessomedusa phasmiformis gen. et sp. nov.

Diagnosis: Medusoid with a tetraradial bell-shaped umbrella with width reaching approximately 40% of umbrella height. Over 90 finger-like tentacles along the oral margin, reaching approximately 15% of umbrella height in length. Stomach cavity located at apex of the umbrella, occupying approximately 30% of the body area. Manubrium extending up to two-thirds the length of the umbrella. Gonads elongate and ovoid, occupying approximately 45% of the umbrella height, located along umbrella corners, but internally positioned approximately halfway between umbrella margins and manubrium.

 Etymology: Genus is a compound name with Burgess referring to the locality, the Burgess Shale, and medusa (Latin) referring to the clade Medusozoa. Species is a compound name with phasma (Greek) and forma (Latin), in reference to the ghostly figure of the umbrella.

  Life reconstruction showing a cluster of Burgessomedusa phasmiformis gen. et sp. nov. swimming above the benthos. This reconstruction is based on the Raymond Quarry Burgess Shale community with clusters of Vauxia sponges represented in the foreground.

Artwork by C. McCall.

Justin Moon, Jean-Bernard Caron and Joseph Moysiuk. 2023. A Macroscopic Free-swimming Medusa from the middle Cambrian Burgess Shale. Proc. R. Soc. B. 29020222490. DOI: 10.1098/rspb.2022.2490

 https://phys.org/news/2023-08-oldest-species-jellyfish.html

[Paleontology • 2023] Computed Tomography and Three-dimensional Reconstruction of the Skull of the Stem Tetrapod Crassigyrinus scoticus

Crassigyrinus scoticus Watson, 1929

in Porro, Rayfield & Clack, 2023.

 DOI: 10.1080/02724634.2023.2183134  

  twitter.com/LauraBPorro

Image by Bob Nicholls 

ABSTRACT

The early tetrapod Crassigyrinus scoticus was a large aquatic predator known from the lower- to mid-Carboniferous (upper Tournasian to upper Visean/lower Serpukovian, approximately 350–330 Ma) of Scotland and Canada. Crassigyrinus is enigmatic in terms of its phylogenetic position due to its unusual morphology, which features a mixture of primitive and derived characters. Previous reconstructions, based on five incomplete and deformed specimens, have suggested a dorsoventrally tall skull with a short and broad snout, large orbits and external nares, and an extended postorbital region. In this study, we scanned four specimens using computed tomography and segmented imaging data to separate bone from matrix and individual bones from each other. Based on these data, we present a revised description of the upper and lower jaws, including sutural morphology and abundant new anatomical information. Damage was repaired and the skull retrodeformed to create a hypothetical three-dimensional reconstruction of the skull of Crassigyrinus that is dorsoventrally flatter than earlier reconstructions, yet still morphologically unique amongst early tetrapods. Overall skull shape, the size and distribution of the teeth, sutural morphology, and the specialized anatomy of the jaw joint and mandibular symphysis all suggest that Crassigyrinus was a powerful aquatic predator capable of hunting and subduing large prey.

CONCLUSIONS: 

The results presented here supplement and amend previous descriptions of C. scoticus, including new information on skull anatomy, sutural morphology, and a detailed description of the jaw joint and mandibular symphysis. Computed tomography and 3D visualization permitted a new 3D reconstruction of the upper and lower jaws of C. scoticus. The reconstructed cranium is dorsoventrally flatter than previous attempts and features a vaulted palate and enormous subtemporal fossae; the new lower jaw is less curved than earlier reconstructions, and the jaw joint is anteromedially tilted rather than transversely oriented. Evidence from skull anatomy, sensory systems, tooth size, shape and distribution, sutural morphology, and the shape and orientation of the jaw joint and mandibular symphysis are used to predict the feeding mechanism and ecology in this unusual stem tetrapod, hypotheses that will be tested further using biomechanical modeling.

Laura B. Porro, Emily J. Rayfield and Jennifer A. Clack. 2023. Computed Tomography and Three-dimensional Reconstruction of the Skull of the Stem Tetrapod Crassigyrinus scoticus Watson, 1929. Journal of Vertebrate Paleontology. e2183134. DOI: 10.1080/02724634.2023.2183134  

  twitter.com/LauraBPorro/status/1653359347143983105

https://www.nhm.ac.uk/discover/news/2023/may/crushed-scottish-fossils-reconstructed-reveal-ancient-predators-skull.html