[Paleontology • 2026] Isodapedon varzealis • A New hyperodapedontine rhynchosaur (Archosauromorpha: Rhynchosauria) from a Cynodont-dominated Site (Upper Triassic) of southern Brazil

 

Isodapedon varzealis  

Schiefelbein, Garcia, Doering & Müller, 2026

DOI: doi.org/10.1098/rsos.260176 

Artwork by Caio Fantini.

 

Abstract

We describe Isodapedon varzealis gen. et sp. nov., a new hyperodapedontine rhynchosaur from the Carnian deposits of the Candelária Sequence, southern Brazil. Phylogenetic analyses place this taxon outside known South American hyperodapedontines, including Macrocephalosaurus mariensis and ‘Hyperodapedon’ species, and support the restriction of the genus Hyperodapedon to its type species, thereby revealing greater diversity within the group than previously recognized. Isodapedon varzealis gen. et sp. nov. is characterized by symmetrical maxillary tooth bearing areas and distinctive dentary morphology, indicating divergent feeding adaptations relative to known rhynchosaurs. Stratigraphic occurrence in beds correlated with the Exaeretodon sub-zone of the Hyperodapedon Assemblage Zone, and its phylogenetic affinities with early diverging hyperodapedontines from Argentina and Scotland, imply a geographically widespread radiation of conservative morphotypes across southwestern Gondwana. This study highlights the complexity of Late Triassic rhynchosaur evolution and underscores the importance of continued palaeontological investigation in refining the taxonomy, biostratigraphy and palaeoecology of this key herbivorous clade.

Keywords: Rhynchosauria, Late Triassic, Candelária Sequence, Archosauromorpha

Subjects:palaeontology

Geological context of the Várzea do Agudo site and provenance of CAPPA/UFSM 0371. (A) Geologic map of the central region of Rio Grande do Sul (southern Brazil) showing the surface distribution of stratigraphic units of the Paraná Basin. (B) Field photograph of the Várzea do Agudo site. (C) Stratigraphic column of the Várzea do Agudo site depicting its fossiliferous content distribution. (D) Life reconstruction of CAPPA/UFSM 0371 by Caio Fantini. (E) Tridimensional model of the partial cranium of CAPPA/UFSM 0371 in right lateral view.

Abbreviations: cs, coarse-sandstone; Fm, formation; fs, fine-sandstone; g, gravel-sandstone; m, mudstone; ms, medium-sandstone. Silhouettes based on artwork by Caio Fantini and Felipe Elias.

Skull and lower jaws of Isodapedon varzealis gen. et sp. nov. (CAPPA/UFSM 0371).
(A) photographs, interpretative illustration and three-dimensional model from surface scan of the skull of CAPPA/UFSM 0371 in right lateral view. (B) Photographs, interpretative illustration and three-dimensional model from surface scan of the skull of CAPPA/UFSM 0371 in left lateral view.

Abbreviations: a, angular; aoc, anguli oris crest; d, dentary; jug, jugal; max, maxilla; mf, mental foramen; pmx l, left premaxilla; pmx r, right premaxilla; sa, surangular; sp, splenial. Black arrow points anteriorly.

Isodapedon varzealis gen. et sp. nov. craniomandibular elements.
 (A) Left skull in lateral view of Isodapedon varzealis gen. et sp. nov. (CAPPA/UFSM 0371) with emphasis on maxillary dentition area (occlusal view). (B) Left lower jaw in medial view with emphasis on lingual dentition area (oblique occlusal view).

Abbreviations: dg, diagonal gaps; lbt, labial teeth; lgt, lingual teeth; ls, longitudinal sulcus; sg, shallow groove; sms, short medial shelf. Black arrow points anteriorly.

Archosauromorpha 

Rhynchosauria  

Rhynchosauridae 

Hyperodapedontinae 

Isodapedon gen. nov.

Type and only species: Isodapedon varzealis sp. nov.

Etymology. The genus name is derived from the Ancient Greek ἴσος (ísos), meaning ‘equal’ or ‘the same’, as a reference to the equally wide tooth-bearing areas of the maxilla.

Isodapedon varzealis sp. nov.

Etymology. The species name refers to the locality of ‘Várzea do Agudo’ in which the specimen was collected.

Diagnosis. The holotype of Isodapedon varzealis is distinguished from all other known rhynchosaurids by the following unique combination of morphological traits (* asterisk denotes autapomorphies): maxilla divided into two tooth-bearing areas by a single longitudinal sulcus; equally wide maxillary lateral and medial tooth-bearing areas; same number (three) of longitudinal rows of teeth in both maxillary lateral and medial tooth-bearing areas; absence of lingual teeth in the medial surface of the maxilla; straight posterior margin of the parietal; sharp sagittal crest extending up to the posterior margin of the parietal; short and rounded ventral process of the squamosal; distinct posterior process in the squamosal; no contact between the lacrimal and palatine; ‘blunt’ and greatly reduced posteroventral process of the dentary; single dorsal blade in the dentary; medial shelf in the medial surface of the posterior portion of the dentary that does not reach half the length of the bone*; medial shelf separated from the dorsal blade of the dentary by a shallow groove; dorsal margin of the posterior portion of the dorsal blade extending markedly further dorsally than the posterior portion of the medial shelf at the level of the posteriormost lingual tooth; and single well-defined row of small, dorsally projected, closely packed lingual teeth in the dentary.

Artistic representation of a Late Triassic landscape of southern Brazil depicting individuals of Isodapedon varzealis gen. et sp. nov. in the foreground and a proterochampsid in the background.

Artwork by Caio Fantini.

 

Jeung Hee Schiefelbein; Maurício Silva Garcia; Mariana Doering and Rodrigo Temp Müller. 2026. A New hyperodapedontine rhynchosaur from a Cynodont-dominated Site (Upper Triassic) of southern Brazil. R Soc Open Sci. 13(4); 260176. DOI: doi.org/10.1098/rsos.260176 [15 Apr 2026]

[PaleoOrnithology • 2025] Aenigmatorhynchus rarus • A remarkable Beak Morphology in a Bird Skull from the Eocene of Messel (Germany) signifies unusual feeding specializations

 Aenigmatorhynchus rarus 

 Mayr & Smith, 2026

DOI: doi.org/10.1098/rsos.250620  

 Researchgate.net/publication/392979376  

 

Abstract

We report the skull of a new avian species from the latest early or earliest middle Eocene fossil site Messel in Germany. Aenigmatorhynchus rarus, gen. et sp. nov. is characterized by a long, straight, and pointed beak, as well as a mandible with prominent processus coronoidei, a very long symphysis, closely adjacent cristae tomiales, and a narrow dorsal sulcus along the tip. This unusual character mosaic impedes a straightforward phylogenetic assignment. In its proportions, the mandible is superficially similar to that of extant stilts (Himantopus, Recurvirostridae) and oystercatchers (Haematopus, Haematopodidae), but some features preclude an assignment of Ae. rarus to these and other charadriiform taxa. The ventral ossification of the rostrum suggests comparisons with long-beaked taxa of the Aequornithes and Telluraves, but again several features conflict with a position of Ae. rarus within either of these clades. Even though an unambiguous phylogenetic placement is not possible, the new fossil expands the avifauna of the Messel site and exhibits a distinctive beak morphology, which is not found in extant birds and indicates a specialized foraging behaviour as yet unknown in birds.

Keywords: Aenigmatorhynchus rarus, gen. et sp. nov., Aves, beak morphology, fossil birds, evolution

Skulls of Aenigmatorhynchus rarus from the latest early or earliest middle Eocene of Messel in Germany. (a) The holotype specimen (SMF-ME 11857A) coated with ammonium chloride. (b), (c) µCT scans of the holotype. (d) The holotype before it was transferred to artificial resin (photograph by Bruno Behr). (e), (f) a referred skull of Ae. rarus in the Pohl collection (PBP-MES−590A+B); coated with ammonium chloride.

 Abbreviations: car, cartilago arytenoidea; cdo, condylus occipitalis; hyo, hyoid apparatus; ios, ventral margin of interorbital septum; jug, jugal bar; lmd, articular (caudal) end of left mandibular ramus; lqd, left quadrate; pal, palatine (os palatinum); ppo, processus postorbitalis; rmd, articular (caudal) end of right mandibular ramus; rps, rostrum parasphenoidale; rpt, right pterygoid; rqd, right quadrate; sym, symphysis mandibulae; tra, tracheal rings. The scale bars equal 10 mm.

Skull and cervical vertebrae of the new avian species Aenigmatorhynchus rarus from the Messel fossil site in Germany. This fossil consists of slab and counter slab and is a referred specimen in a private collection. It was coated with ammonium chloride to enhance the contrast; the scale bar equals 10 mm. 

 

 Aves Linnaeus, 1758

  Order and family incertae sedis

Aenigmatorhynchus, gen. nov. 

 Diagnosis: The new taxon is characterized by a long, straight, mediolaterally narrow and pointed beak, which reaches about 75% of the entire skull length; the mandibular symphysis is very long and measures about half the length of the mandible; the rami mandibularum run in parallel in the rostral half of the mandible; the mandible exhibits prominent processus coronoidei and its tip forms a trough-like dorsal sulcus. The latter two features probably represent autapomorphies of the new taxon.

Etymology: The genus name is derived from aenigma (Lat.), riddle—which in turn is derived from αἴνιγμα (Gr.), speaking in riddles—and ῥύγχος (Gr.), beak; the taxon name refers to the unusual character distribution shown by the mandible of the new species.

  Aenigmatorhynchus rarus, sp. nov.

Etymology: The species epithet is derived from rarus (Lat.), rare, in reference to the fact that the holotype skull currently is the only record of the species in a public collection.

 

Gerald Mayr and Krister Smith . 2026. A remarkable Beak Morphology in a Bird Skull from the Eocene of Messel (Germany) signifies unusual feeding specializations. R Soc Open Sci. 12(6): 250620. DOI: doi.org/10.1098/rsos.250620 [25 Jun 2025] 

 Researchgate.net/publication/392979376_A_remarkable_beak_morphology_in_a_bird_skull_from_the_Eocene_of_Messel_Germany

[Ichthyology • 2025] Gambusia nobilis, G. pyrros & G. echelleorum • A Total Evidence Approach justifies Taxonomic Splitting of the Endangered Pecos gambusia (Cyprinodontiformes: Poeciliidae: Gambusia) into Three Species

 Gambusia nobilis (Baird & Girard 1853)

Gambusia pyrros 
Gambusia echelleorum 

 Portnoy, Bretzing-Tungate, Fields, Bean, Smith, Dolan, Blanchard & Conway, 2025 

DOI: doi.org/10.1098/rsos.251025

Abstract

Gambusia nobilis is a federally endangered species found across a fragmented distribution within the Pecos River Drainage of Texas and New Mexico, USA. Drought, human water usage, and potential hybridization and competition with introduced congeners threaten species persistence. Therefore, a population genomics study was conducted to provide critical information for conservation planning. Unsupervised clustering suggested hierarchical structure, with a primary K = 3, and deep divergences were detected among samples grouped into the Leon Creek watershed, the Toyah Creek watershed, and water bodies within the Bitter Lake National Wildlife Refuge (F’ST = 0.55–0.76 for putatively neutral data). Phylogenetic analyses showed three distinct clades corresponding to these groups, with divergence times estimated to be in the last 50 000 years. Complimentary morphological analyses detected differences among the three groups, including features of male colour pattern, and the number of caudal-fin rays in both sexes. Taken as a whole, the results indicate that the endangered G. nobilis comprises three species (two of which are named herein as G. pyrros n. sp. and G. echelleorum n. sp.), rather than one, and the study highlights the daunting yet critical task of documenting species diversity during a period of unprecedented diversity loss.

Keywords: Chihuahua desert, genetic drift, taxonomy, Poeciliidae, species delimitation

Subjects:biology, evolution, genomics, taxonomy and systematics

Distribution and relationships of the Gambusia nobilis species complex.
  (a) Map showing distribution of G. nobilis, G. pyrros n. sp. and G. echelleorum n.sp. within Chihuahuan desert ecoregion of western Texas and southeastern New Mexico. (b) Closer view of area surrounded by dashed rectangle (b) in (a), showing location of G. echelleorum samples from Bitter Lake watershed in New Mexio, type locality indicated by black asterisk (*). (c) Closer view of area surrounded by dashed rectangle (c) in (a), showing location of G. nobilis samples from Leon Creek watershed and G. pyrros samples from Toyah Creek watershed in Texas, type localities indicated by black asterisk (*).
(d) Clade equivalent to the Gambusia nobilis species complex from the Maximum Likelihood phylogram based on 5989 loci showing relationships of G. nobilis, G. pyrros and G. echelleorum, numbers above branches represent bootstrap values (full topology available in electronic supplementary material, figure S7). (e) Discriminant analysis of principal components using the unsupervised clustering algorithm, K-means (= 3), using 3502 single nucleotide polymorphism-containing loci and 212 individuals (G. nobilis, n = 63; G. pyrros, n = 79; G. echelleorum, n = 70). Basemap in (a) created with SimpleMappr. Satellite images in (b) and (c) obtained from Google Earth.

Male individuals of the three members of the Gambusia nobilis species complex photographed in life against different background and in different views (lateral and dorsal) to document variation in colour pattern.
(a) Left side, lateral view, against light grey background: (i) G. nobilis (TCWC 21102.01); (ii, iii) G. pyrros (TCWC 21103.02, paratypes); (iv) G. echelleorum (TCWC 21104.01, holotype); (v-vii) G. echelleorum (TCWC 21105.01, paratypes). (b) Left side, lateral view, against dark grey background: (i, ii) G. nobilis (TCWC 21102.01); (iii) G. pyrros (TCWC 21103.02, paratype); (iv) G. echelleorum (TCWC 21104.01, holotype); (v) G. echelleorum (TCWC 21105.01, paratype). (c) Dorsal view (background variable): (i, ii) G. nobilis (TCWC 21102.01); (iii, iv) G. pyrros (TCWC 21103.02, paratypes); (v) G. echelleorum (TCWC 21104.01, holotype); (vi) G. echelleorum (TCWC 21105.01, paratype

 Gambusia nobilis (Baird & Girard 1853)

  Gambusia pyrros new species

Diagnosis: A member of the Gambusia nobilis species group (sensu Rauchenberger [1989]) most similar to G. nobilis and G. echelleorum. The characters distinguishing G. pyrros from G. nobilis are listed in the diagnosis of the latter. Gambusia pyrros is distinguished from G. echelleorum by the same characters that distinguish G. nobilis from G. echelleorum, plus: body colour of males orange-red or yellow-orange (figures 1d and 2b(ii); electronic supplementary material, figure S8) (versus yellow-grey to light cream; figures 1d and 2b(iii); electronic supplementary material, figure S8), anal fin of male orange-red at base in life (figure 2d(ii)) (versus orange; figure 2d(iii)), a higher modal number of total caudal-fin rays (29–32, mode 31 versus 25–29, mode 27; figure 2e), a higher modal number of branched caudal-fin rays (12–15, mode 14 versus 9–14, mode 12).

Etymology: From the Greek pyrros, meaning flame-coloured, a reference to the bright yellow, orange and red colours of the median fins of males in life. A noun in apposition. Proposed common name: flame gambusia.

  Gambusia echelleorum new species

Diagnosis: A member of the Gambusia nobilis species group (sensu Rauchenberger [1989]) most similar to G. nobilis and G. pyrros. The characters distinguishing G. echelleorum from G. nobilis and G. pyrros are listed in the diagnoses provided for the latter two.

Etymology: Named for Alice and Anthony Echelle in honour of their work on Gambusia nobilis. A noun in the genitive. Proposed common name: New Mexico Gambusia.

David S. Portnoy; Robert J. Bretzing-Tungate; Andrew T. Fields; Megan G. Bean; Ryan K. Smith; Elizabeth P. Dolan; Rose Blanchard and Kevin W. Conway. 2025. A Total Evidence Approach justifies Taxonomic Splitting of the Endangered Pecos gambusia into Three Species. R Soc Open Sci. (2025) 12 (11): 251025. DOI: doi.org/10.1098/rsos.251025 [26 Nov 2025]

 

[Paleontology • 2025] Enigmacursor mollyborthwickae • A neornithischian Dinosaur from the Upper Jurassic Morrison Formation of the western USA

Enigmacursor mollyborthwickae

Maidment & Barrett, 2025

 

DOI: doi.org/10.1098/rsos.242195

Artwork by Bob Nicholls.

Abstract

Although their remains have been known since the 1870s, the small, bipedal ornithischian dinosaurs from the Upper Jurassic Morrison Formation of the western USA remain poorly known. The historic type specimens are incomplete and poorly preserved and have recently been designated as nomina dubia. Here, we describe a recently collected, partial but three-dimensionally preserved skeleton of a new small-bodied ornithischian from the Morrison Formation of Colorado, USA, that we name Enigmacursor mollyborthwickae gen. et sp. nov. The skeleton includes substantial portions of the axial and appendicular skeleton and, when scored into a phylogenetic analysis, is shown to be a non-cerapodan neornithischian, whose closest relative is Yandusaurus hongheensis from the Late Jurassic of China. The discovery of Enigmacursor enhances the diversity of ornithischian dinosaurs from the Morrison Formation and provides new information on their anatomy. In addition, it demonstrates that there is additional cryptic diversity of small-bodied Morrison Formation ornithischians, suggesting they were a more diverse component of these Late Jurassic ecosystems than was previously realized.

Systematic palaeontology

Dinosauria (Owen 1842)

Ornithischia (Seeley 1888)

Neornithischia (Cooper 1985)

Enigmacursor mollyborthwickae gen. et sp. nov.

Holotype—NHMUK PV R 39000, a partial skeleton that includes three teeth, three cervical, 11 dorsal, two dorsosacral and five caudal vertebrae, 10 dorsal ribs, five chevrons, right sternum, both scapulae, both humeri, both radii, both ulnae, three metacarpals, left ilium, right ischium, right pubis, both femora, both tibiae, both fibulae, right astragalus and both pedes.

Diagnosis—Enigmacursor mollyborthwickae differs from all other ornithischian dinosaurs in possessing the following unique combination of features and one potential autapomorphy (the latter marked with an asterisk): (1) posterior articular facets offset ventrally relative to anterior articular facets on proximal dorsal vertebrae*; (2) absence of a supracetabular crest on the ilium; (3) femoral head separated from the greater trochanter by a trochanteric fossa; (4) apex of anterior trochanter situated level with the ventral margin of the femoral head; (5) absence of a ligament sulcus on the posterior surface of the femoral head; (6) ventral surface of fourth trochanter straight or slightly convex in medial or posterior view; (7) medially directed, hook-like posterior condyle of the proximal end of the tibia.

Etymology—Enigma, meaning a puzzle or mystery, in reference to the convoluted taxonomic history of small-bodied ornithischians from the Morrison Formation; cursor, from the Latin for ‘runner’, in reference to the cursorial morphology of the elongated hind limb and pes. The species name honours Molly Borthwick, whose generous donation allowed the NHMUK to acquire the specimen.

Enigmacursor mollyborthwickae
a) Skeletal reconstruction of with preserved elements shaded.
b) Life reconstruction. Artwork by Bob Nicholls.

Susannah C. R. Maidment and Paul M. Barrett. 2025. Enigmacursor mollyborthwickae, a neornithischian dinosaur from the Upper Jurassic Morrison Formation of the western USA. R. Soc. Open Sci. 12: 242195. DOI: doi.org/10.1098/rsos.242195 [25 June 2025]

https://www.nhm.ac.uk/discover/news/2025/june/new-species-mystery-dinosaur-unveiled-natural-history-museum.html

   

[Paleontology • 2025] Tail of Defence: An Almost complete Tail Skeleton of Plateosaurus (Sauropodomorpha, Late Triassic) reveals possible Defence Strategies

 

Plateosaurus trossingensis 

in Filek, Kranner, Pabst et Göhlich, 2025.

DOI: doi.org/10.1098/rsos.250325 

Abstract

In 2015, a partial skeleton of the Late Triassic dinosaur Plateosaurus trossingensis was excavated from Frick, Switzerland, and subsequently mounted at the Natural History Museum of Vienna in 2021. This specimen includes an almost complete series of tail vertebrae, with a well-preserved, articulated whip-like distal end. The preserved tail structure provides valuable insights into the morphological implications of tail function and its potential role in the behaviour of Plateosaurus. Using the caudal vertebrae, we reconstructed and analysed the potential tail-lashing capabilities of Plateosaurus, comparing its biomechanics with those of other fossil and extant long-tailed reptilian taxa, including the extinct sauropod Diplodocus, the extant Asian water monitor (Varanus salvator), and the green iguana (Iguana iguana). Our results indicate that the tail of P. trossingensis was highly flexible, with an estimated kinetic energy output ranging between 0.537 and 1.616 kJ during rapid strikes, comparable to the defensive tail use observed in modern reptiles. These findings suggest that tail-whipping may have played a role in predator deterrence and intraspecific interactions in Plateosaurus.

Keywords: Plateosaurus, behaviour, defence strategy, Triassic, Frick, Switzerland

 Reconstruction of a Plateosaurus herd featuring three juveniles and an adult, which is hypothetically depicted in the act of lashing its tail in defence against a predator

(Copyright: Daria Filek and Thomas Filek).

 

Thomas Filek, Matthias Kranner, Ben Pabst and Ursula B. Göhlich. 2025. Tail of Defence: An Almost complete Tail Skeleton of Plateosaurus (Sauropodomorpha, Late Triassic) reveals possible Defence Strategies. Royal Society Open Science. DOI: doi.org/10.1098/rsos.250325 [21 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] Maleriraptor kuttyi • A new herrerasaurian dinosaur from the Upper Triassic Upper Maleri Formation of south-central India

 

 Life reconstruction of Maleriraptor kuttyi with the unaysaurid sauropodomorph Jaklapallisaurus asymmetricus, both from the lower Norian Upper Maleri Formation of south-central India. 

Ezcurra, Garcia, Novas, Müller, Agnolín & Chatterjee, 2025

DOI: doi.org/10.1098/rsos.250081 

 Researchgate.net/publication/391521510

Artwork by Márcio L. Castro.

Abstract

Some of the oldest known dinosaurs and the first faunas numerically dominated by them are documented in the Upper Triassic–Lower Jurassic-aged Gondwana formations exposed in the Pranhita-Godavari Valley of south-central and east-central India. The Upper Maleri Formation of the Pranhita-Godavari Basin preserves an early-middle Norian dinosaur assemblage numerically dominated by sauropodomorph dinosaurs, including at least two nominal species. However, the preliminary report of a herrerasaurian dinosaur specimen indicates that this assemblage of south-central Gondwana was more taxonomically diverse. Here, we describe and compare in detail the anatomy and assess the taxonomy and phylogenetic relationships of the Upper Maleri herrerasaurian specimen. A unique combination of character states present in this specimen allows the erection of the new genus and species Maleriraptor kuttyi. Updated quantitative phylogenetic analyses focused on early dinosauriforms recovered Maleriraptor kuttyi as a member of Herrerasauria outside of the South American clade Herrerasauridae. Maleriraptor kuttyi fills a temporal gap between the Carnian South American herrerasaurids and the younger middle Norian–Rhaetian herrerasaurs of North America. Maleriraptor kuttyi shows the first evidence that herrerasaurs survived also in Gondwana the early Norian tetrapod turnover that resulted in the global extinction of the rhynchosaurs.

Keywords: Dinosauria, Saurischia, Herrerasauria, Norian, Late Triassic, Pranhita-Godavari

Dinosauria Owen, 1842 [Langer et al., 2020]  

Saurischia Seeley, 1887 [Gauthier et al., 2020]  

Herrerasauria Galton, 1985 sensu Langer, 2004 

Maleriraptor gen. nov.

Etymology: The genus name is derived from the Upper Maleri Formation, in which the holotype and only known specimen was collected, and the Greek word raptor, thief, which is an ending usually used for predatory dinosaur genera.

Maleriraptor kuttyi sp. nov.

Holotype: ISIR 282, a first primordial sacral vertebra with its right rib and the base of the left rib, the distalmost portion of a right second sacral rib, a caudosacral or first caudal vertebra, an anterior caudal vertebra, right ilium, proximal and distal ends of right pubis and proximal end of left pubis (figure 1a, figures 2−5).

Stratigraphic and geographic occurrence: Upper Maleri Formation (early Norian, Late Triassic), Pranhita-Godavari Valley, around 1 km south of the Annaram village, south-central India (figure 1b,c). ISIR 282 was collected more than 40 years ago and we lack georeferenced data.

Diagnosis: Maleriraptor kuttyi is an early diverging dinosauriform that differs from all other Triassic archosaurs in the presence of the following unique combination of character states (autapomorphy indicated with an asterisk): centrum posterior to the second primordial sacral vertebra longer than each of the primordial sacral centra; ilium with a postacetabular process shorter than 0.6 times the length between the pubic and ischial peduncles, absence of brevis fossa, lateral rugosity of the iliac postacetabular process restricted to its posterior-most tip*; pubis with ventrally directed shaft; and pubis with a very poorly developed distal anteroposterior expansion.

Etymology: The species name commemorates the late T. S. Kutty, who discovered the holotype and co-authored its preliminary description with some of the authors of this study (M.D.E., F.E.N., S.C.).

 Life reconstruction of Maleriraptor kuttyi with the unaysaurid sauropodomorph Jaklapallisaurus asymmetricus, both from the lower Norian Upper Maleri Formation of south-central India.

Artwork by Márcio L. Castro.

Martín D. Ezcurra, Maurício Silva Garcia, Fernando E. Novas, Rodrigo Temp Müller, Federico L. Agnolín and Sankar Chatterjee. 2025. A new herrerasaurian dinosaur from the Upper Triassic Upper Maleri Formation of south-central India. Royal Society Open Science. 12(5):250081. DOI: doi.org/10.1098/rsos.250081 [07 May 2025]

  Researchgate.net/publication/391521510_A_new_herrerasaurian_dinosaur_from_the_Upper_Triassic_Upper_Maleri_Formation_of_south-central_India

[Mollusca • 2025] Pararosa vigarae • The Accordion Worm: A New Genus and Species of heteronemertean (Nemertea: Pilidiophora) from Galicia (Spain)

  

Pararosa vigarae  Junoy & Verdes, 

in Verdes, Gracia-Sancha, Pérez-Dieste, Conejero, Campos, Leiva, Taboada, Riesgo et Junoy, 2025.

Accordion worm | gusano acordeón  ||  DOI: doi.org/10.1098/rsos.250313

Abstract

Ribbon worms (Nemertea) are a less-known group of invertebrates, specially challenging for taxonomic studies due to the scarcity of external morphological features. As a consequence, the number of known nemertean species might represent just a small fraction of the true diversity of the phylum. The present study increases the number of known ribbon worm species with the description of the accordion worm Pararosa vigarae sp. nov., a new genus and species of Heternonemertea from the northwest coast of Spain. We performed molecular phylogenetic analyses based on partial sequences of 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I (COI) and histone H3 gene markers that indicated the newly identified specimens represent a new genus and species of heteronemertean in the family Lineidae. We also provide morphological data and images illustrating its unique behaviour, contracting its body into a series of rings similar to an accordion. Our results increase our knowledge on the diversity of an important but often overlooked invertebrate phylum and emphasize the need to combine morphological and molecular data to discover new ribbon worm species and better evaluate the true diversity of the phylum.

Keywords: accordion worm, Heteronemertea, Lineidae, Nemertea, Pararosa vigarae, ribbon worm

 

 Live images of Pararosa vigarae sp. nov.
 (A) Dorso-lateral view of head, showing cephalic slits; (B) anterior end, dorso-lateral view, showing detail of head tip; (C) ventral view of head, the mouth appears as a whitish middle line just behind the cephalic slits; (D) complete specimen with contracted body, showing epidermal rings; (E) dorsal view of complete specimen in a relaxed state, showing epidermal rings.

PILIDIOPHORA Thollesson and Norenburg, 2003

Class HETERONEMERTEA Coe (1901)

Family LINEIDAE McIntosh, 1874

Genus Pararosa gen. nov.

Diagnosis. Heteronemertean with a single pair of horizontal lateral cephalic slits which posteriorly form deep intramuscular canals; proboscis simple, unbranched; nervous system without neurochord or neurochord cells; dermis thick, glandular region separated from body wall muscles by well-developed connective tissue layer; blood system with cephalic lacunae; frontal sensory organs consisting of three simple ciliated pits located at the tip of the head; eyes absent.

Etymology. The name refers to the type locality of the type species, the ría de Arosa, preceded by the Spanish word par (pair), referring to the two localities where the specimens were collected. The name of the type locality in Spanish is feminine, and thus the new genus name is also feminine.

Type species. Pararosa vigarae sp. nov.

Pararosa vigarae sp. nov. Junoy & Verdes

Diagnosis. Heteronemertean with brown to dark green body, head shape retuse; ocelli absent; contracts into regular rings that persist as annular constrictions when stretched.

Etymology. Named after Rosa Vigara, wife of the senior author, as a gift for their golden wedding anniversary. Specific epithet is a noun, in reference to the last name Vigara.

Common name. Accordion worm. 

Spanish common name: gusano acordeón.

 

Aida Verdes, Carlota Gracia-Sancha, Jacinto Pérez-Dieste, María Conejero, Patricia Alvarez Campos, Carlos Leiva, Sergi Taboada, Ana Riesgo and Juan Junoy. 2025. The Accordion Worm: A New Genus and Species of heteronemertean (Nemertea, Pilidiophora) from Galicia (Spain). R. Soc. Open Sci. 12; 250313. DOI: doi.org/10.1098/rsos.250313 [07 May 2025]

 

[Paleontology • 2025] Rise of the King: Gondwanan Origins and Evolution of Megaraptoran Dinosaurs

Gondwanan Origins and Evolution of Megaraptoran Dinosaurs

in Morrison, Scherer, O’Callaghan, Layton, Boisvert, Rolando, Durrant, Salas, Allain et Gascoigne, 2025. 

DOI: doi.org/10.1098/rsos.242238 

 

Abstract

Late Cretaceous Earth was dominated by theropods such as tyrannosauroids and megaraptorans; however, it is unclear how these clades diversified and grew to massive proportions. This study aimed to conduct a biogeographical analysis and test climate as a potential mechanism for the increase in size. We used published phylogenetic matrices with the R package BioGeoBears to test different biogeographical hypotheses for both clades. We mapped body mass (BM) and body length against known climate data to test this potential hypothesis. Continental-scale variance did not drive tyrannosauroid biogeography and instead widespread ancestral populations, sympatric speciation and localized extinctions throughout these clades constricted geographic range. Both patterns were supported by statistical analyses. This biogeographical model also indicates the ancestor of the clade Tarbosaurus and Tyrannosaurus was present in both Asia and Laramidia, and therefore the ancestor of Tyrannosaurus came from Asia. Statistical data illustrated no correlation between Mean Annual Temperature (MAT) and BM but potential climatic shifts may be associated with gigantism in derived megaraptorids and eutyrannosaurians. This biogeographical model implies megaraptorans may have had a cosmopolitan distribution prior to the splitting of Laurasia and Gondwana. Also, gigantism in these clades may be associated with climatic shifts in the Late Cretaceous.

Keywords: Biogeography, Late Cretaceous, Megaraptora, Tyrannosauroidea

 

The end Cretaceous Northern Hemisphere fauna was dominated by Tyrannosaurids (such as Tyrannosaurus rex), hadrosaurs and ceratopsian ornithischian dinosaurs.

Artwork by Pedro Salas and Sergey Krasovskiy.

Potential dispersal routes for megaraptorans during the Middle Jurassic–Early Cretaceous (approx. 143 Ma). ...

Cassius Morrison, Charlie Roger Scherer, Ezekiel V. O’Callaghan, Collin Layton, Colin Boisvert, Mauro Aranciaga Rolando, Leroy Durrant, Pedro Salas, Steven J. R. Allain and Samuel J. L. Gascoigne. 2025. Rise of the King: Gondwanan Origins and Evolution of Megaraptoran Dinosaurs. R. Soc. Open Sci. 12: 242238. DOI: doi.org/10.1098/rsos.242238  [07 May 2025] 

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[PaleoIchthyology • 2025] Pararhincodon torquis • Three-dimensional Fossils of a Cretaceous Collared Carpet Shark (Orectolobiformes: Parascylliidae) shed light on Skeletal Evolution in galeomorphs

 

 Pararhincodon torquis

Dearden, Johanson, O’Neill, Miles, Bernard, Clark, Underwood & Rücklin, 2025

 DOI: doi.org/10.1098/rsos.242011 

Artwork by Julio Lacerda

 

Abstract

A rich fossil record of teeth shows that many living shark families’ origins lie deep in the Mesozoic. Skeletal fossils of the sharks to whom these teeth belonged are far rarer and when they are preserved are often flattened, hindering understanding of the evolutionary radiation of living shark groups. Here we use computed tomography to describe two articulated Upper Cretaceous shark skeletons from the Chalk of the UK preserving three-dimensional neurocrania, visceral cartilages, pectoral skeletons and vertebrae. These fossils display skeletal anatomies characteristic of the Parascylliidae, a family of Orectolobiformes now endemic to Australia and the Indo Pacific. However, they differ in having a more heavily mineralized braincase and a tri-basal pectoral fin endoskeleton, while their teeth can be attributed to a new species of the problematic taxon Pararhincodon. Phylogenetic analysis of these new fossils confirms that Pararhincodon is a stem-group parascylliid, providing insight into the evolution of parascylliids’ distinctive anatomy during the late Mesozoic–Cenozoic shift in orectolobiform biodiversity from the Northern Atlantic to the Indo Pacific. Meanwhile both Pararhincodon and extant parascylliids have a distinctive vertebral morphology previously described only in Carcharhiniformes, contributing a skeletal perspective to the picture emerging from macroevolutionary analyses of coastal, small-bodied origins for galeomorphs.

Keywords: Elasmobranchii, Orectolobiformes, Galeomorphii, CT scanning, Cretaceous

 

Class. Chondrichthyes Huxley, 1880

Subclass. Elasmobranchii Bonaparte, 1838

Superorder. Galeomorphii Compagno, 1973

Order. Orectolobiformes Applegate, 1972

Family. Parascylliidae Gill, 1862

Genus: Pararhincodon Herman in Cappetta, 1976

  Pararhincodon torquis n. sp.

Holotype specimen: NHMUK PV P 73821 a

Diagnosis of species: Very small, strongly asymmetrical teeth. Cusp triangular with sharp cutting edge, strongly bent lingually and distally. Lateral cusplet on distal edge of tooth, absent on mesial edge which is developed into slight shoulder. Base of cusp has a labial bulge and the medial section is developed into a low labial protuberance. Parallel folds present at the base of the cusp, some of which travel up the cusp’s face. Root flat and developed into mesial and distal lobes with deep, open nutrient groove.

 

Derivation of name: From torc, a metal collar associated with cultures from the European Iron Age.

Richard P. Dearden, Zerina Johanson, Helen L. O’Neill, Kieran Miles, Emma L. Bernard, Brett Clark, Charlie J. Underwood and Martin Rücklin. 2025. Three-dimensional Fossils of a Cretaceous Collared Carpet Shark (Parascylliidae, Orectolobiformes) shed light on Skeletal Evolution in galeomorphs. R. Soc. Open Sci. 12: 242011. DOI: doi.org/10.1098/rsos.242011 [30 April 2025]