[Paleontology • 2025] The Ecology and Geography of Temnospondyl Recovery after the Permian–Triassic Mass Extinction

 

 Temnospondyls of the Triassic.

in Mehmood, Singh, Elsler et Benton, 2025. 

DOI: doi.org/10.1098/rsos.241200 

artwork by Mark P. Witton  

Abstract

One of the mysteries of the Permian–Triassic mass extinction was the subsequent success of temnospondyls. Temnospondyls were key early tetrapods in the Carboniferous and Permian and hardly seem to be ideal pioneers in a tough post-extinction world. Did they survive because of some unusual adaptations or by occupying some limited part of the world? We explore temnospondyl success in the Triassic by comparing their functional ecomorphology and palaeogeographic distributions. We find that Early Triassic temnospondyls exhibited all skull sizes and shapes, reflecting a wide diversity of feeding modes: abundant parabolic-snouted forms, and less common longirostrine (long-snouted) and insectivorous (short-skulled) forms. In fact, morphospace occupation by temnospondyls increased dramatically from Late Permian to Early Triassic, and then decreased in the Middle Triassic, but without emphasis on one feeding mode or another. Nor is there any evidence for unusual patterns of evolution: Temnospondyli and subclade Trematosauria follow an Ornstein–Uhlenbeck evolutionary model, suggesting evolution towards a common skull shape. Metoposauroidea, Brachyopoidea and basal Stereospondyli evolved by the stasis model. Further, these Early Triassic temnospondyls did not occupy a limited part of the world; they show temperate distributions, but with some specimens in equatorial regions, contradicting the idea of a permanently impermeable tropical dead zone.

Keywords: geometric morphometrics, ecological function, temnspondyli, Triassic, Permian–Triassic mass extinction

 Temnospondyls of the Triassic.
(a) simplified phylogeny of the temnospondyl clades investigated here, with two paraphyletic assemblages, ’basal temnos’ and basal ’stereos’. Amphibamiformes are a clade within Dissorophoidea, comprising Micropholidae and Lissamphibia. Branches stemming from coloured nodes depict subclades of this node.
(b) three functional groupings based on skull morphology: large parabolic skulls characteristic of generalists such as extant crocodilians; generalist insectivore with short and wide skulls as in modern frogs; and longirostrine, adapted for fast, weak bites usually in fish eating, as in modern gharials.

Abbreviations: Stereo., Sterospondyli; Temno., Temnospondyli.

Silhouette images from Phylopic (https://www.phylopic.org: Dmitry Bogdanov (Metoposaurus, Lydekkerina, Batrachosuchus, Pelorocephalus, Trematosaurus) all CC0 3.0; Steven Traver (Dendrobates) CC0 1.0). Nix Draws Stuff/Nix illustration (Eryops) CC0 4.0. Silhouette images from Wikimedia Commons (https://commons.wikimedia.org: Smokeybjb (Eolydekkerina magna, Deltasaurus kimberleyensis); Nobu Tamura (Gerrothorax BW and Wetlugasaurus BW) all CC0 3.0). Vector graphics: Mike Prince (Gharial) CC0 2.0; Momotarou, 2012 (Andrias japonicus) CC0 3.0; CDC (African Dwarf Frog) Public Domain. Skull Graphics vectorized by AM; Aphaneramma [Fortuny, et al. 2018]; Cyclotosaurus [Schoch & Milner, 2014] and Triadobatrachus [Ascarrunz, et al. 2016].

  Mastodonsaurus vs. Jaxtasuchus

artwork by Mark P. Witton  

www.MarkWitton.co.uk

Aamir Mehmood, Suresh A. Singh, Armin Elsler and Michael J. Benton. 2025. The Ecology and Geography of Temnospondyl Recovery after the Permian–Triassic Mass Extinction. R. Soc. Open Sci. 12: 241200. DOI: doi.org/10.1098/rsos.241200 [05 March 2025]

Amphibians bounce-back from Earth’s greatest mass extinction

https://www.bristol.ac.uk/news/2025/march/amphibians-bounce-back-from-extinction-event.html

Ancient frog relatives survived the aftermath of the largest mass extinction of species by feeding on freshwater prey that evaded terrestrial predators, University of Bristol academics have found.

In the study, published today in the journal Royal Society Open Science, their findings suggest the amphibians’ success lay in their generalist feeding ecology, enabling them to feed on a wide variety of prey despite the array of environmental changes happening all around them through the Triassic.

...

  x.com/MarkWitton/status/1376637860141539335

[Paleontology • 2024] Melkamter pateko • The Oldest monofenestratan Pterosaur from the Queso Rallado locality (Cañadón Asfalto Formation, Toarcian) of Chubut Province, Patagonia, Argentina

 Melkamter pateko

 Fernandes, Pol & Rauhut, 2024 

DOI: doi.org/10.1098/rsos.241238 

Artistic reconstruction by Pedro Andrade.

 

Abstract

As the first group of tetrapods to achieve powered flight, pterosaurs first appeared in the Late Triassic. They proliferated globally, and by the Late Jurassic through the Cretaceous, the majority of these taxa belonged to the clade Monofenestrata (which includes the well-known Pterodactyloidea as its major subclade), typified by their single undivided fenestra anterior to the orbit. Here, a new taxon Melkamter pateko gen. et sp. nov., represented by the specimen MPEF-PV 11530 (comprising a partial cranium and associated postcranial elements), is reported from the latest Early Jurassic (Toarcian) locality of Queso Rallado (Cañadón Asfalto Formation) and referred to the clade Monofenestrata, increasing our previously known taxonomic and geographic representations, and temporal range for this clade. This occurrence marks the oldest record of Monofenestrata globally and helps to shed critical light on the evolutionary processes undergone during the ‘non-pterodactyloid’-to-pterodactyloid transition within the Pterosauria. In addition, another single isolated tooth from the same locality shows ctenochasmatid affinities. These finds further elucidate the still-poor Gondwanan Jurassic pterosaur fossil record, underscoring that most of our current ideas about the timing and modes of pterosaur evolution during that period are largely based on (and biased by) the pterosaur fossil record of the Northern Hemisphere.

Keywords: Pterosauria, Monofenestrata, Jurassic, Toarcian, Patagonia, Argentina

  Comparison of (a) Darwinopterus linglongensis (IVPP V16049; mirror-imaged for comparison), (b) Melkamter pateko, and the newly- prepared left side of (c) Cuspicephalus scarfi.

Scale bars are 1 cm.

 Systematic palaeontology

PTEROSAURIA Owen, (1842) 

MONOFENESTRATA Lü et al. (2010) sensu Andres et al. (2014)

Genus Melkamter, gen. nov.

 Melkamter pateko, sp. nov.

  Etymology: Genus name ‘Melkamter’ from the native Tehuelche word ‘mel’ meaning (in Spanish/English) ‘ala/wing’ and ‘kamter’ meaning ‘lagarto grande/big lizard’ (after the original translation of ‘pterosaur’ as ‘winged lizard’); the species epithet ‘pateko’ is derived from ‘pate’ meaning ‘rallado/rasped’ and ‘ko’ meaning ‘conjunto de huesos/set of bones’, an ode to both to the site of Queso Rallado, and the fractured preservational state of the fossil (translations from [60]).

Holotype: MPEF-PV 11530 (Museo Paleontólogico Egidio Feruglio, Trelew, Argentina), consisting of at least a partial cranium (with counterslab) and two associated teeth, four dorsal vertebrae, one metacarpal (either I, II or III) and other bone fragments.

 Type locality and Horizon: Locality Queso Rallado, close to Cerro Cóndor, northern central Chubut Province, Argentina. Lower section of the Cañadón Asfalto Formation, latest Early Jurassic, Toarcian.

 Diagnosis: Non-pterodactyloid monofenestratan with a confluent naris and anteorbital fenestra and quadrate inclined at about 120°. Autapomorphies include: the presence of a small vestigial ascending process in the maxilla that does not reach the nasal or lacrimal dorsally; a maxillary body anterior to the vestigial ascending process that is higher than a posterior portion, with both portions divided by the vestigial ascending process delimited by a marked step; lacrimal and posterior processes of the jugal offset at about 55° angle. The taxon can furthermore be diagnosed by a combination of characters, including the marked dorsal deflection of the dorsal margin of the skull at the beginning of the nasoantorbital fenestra, resulting in a concave rather than straight outline of the dorsal skull margin in this region in lateral view, and the pointed anterior process of the quadratojugal that separates the posterior ends of the jugal and the maxilla.

 Artistic reconstruction of  Melkamter pateko 

by Pedro Andrade.

Alexandra E. Fernandes, Diego Pol and Oliver W. M. Rauhut. 2024. The Oldest monofenestratan Pterosaur from the Queso Rallado locality (Cañadón Asfalto Formation, Toarcian) of Chubut Province, Patagonia, Argentina. R. Soc. Open Sci.11: 241238. DOI: doi.org/10.1098/rsos.241238 

https://nachrichten.idw-online.de/2024/12/11/a-new-species-of-flying-reptiles-reshuffles-the-timeline-of-pterosaur-evolution

[Mammalogy • 2024] Orcinus rectipinnus & O. ater • Revised Taxonomy of eastern North Pacific Killer Whales (Orcinus orca): Bigg’s and Resident Ecotypes deserve Species Status

 

 Bigg’s killer whale Orcinus rectipinnus (Cope in Scammon, 1869)
Resident killer whale Orcinus ater (Cope in Scammon, 1869)

in Morin, McCarthy Fung, Durban, Parsons, Perrin, Taylor, Jefferson & Archer, 2024.

DOI: 10.1098/rsos.231368 

twitter.com/EmmaLuck22

Abstract

Killer whales (Orcinus orca) are currently recognized as a single ecologically and morphologically diverse, globally distributed species. Multiple morphotypes or ecotypes have been described, often associated with feeding specialization, and several studies have suggested taxonomic revision to include multiple subspecies or species in the genus. We review the ecological, morphological and genetic data for the well-studied ‘resident’ and Bigg’s (aka ‘transient’) ecotypes in the eastern North Pacific and use quantitative taxonomic guidelines and standards to determine whether the taxonomic status of these killer whale ecotypes should be revised. Our review and new analyses indicate that species-level status is justified in both cases, and we conclude that eastern North Pacific Bigg’s killer whales should be recognized as Orcinus rectipinnus (Cope in Scammon, 1869) and resident killer whales should be recognized as Orcinus ater (Cope in Scammon, 1869).

Keywords: Cetacea, odontocete, speciation

 

  Vertical images of (a) an adult male Bigg’s killer whale (BKW) from the West Coast Transient population of Bigg’s killer whales and (b) an adult male resident killer whale (RKW) from the sympatric Southern Resident population of resident killer whales.
Images are scaled to the estimated asymptotic lengths of 7.3 m and 6.9 m, respectively. Vertical images were collected using an octocopter drone using methods described by Durban et al. [2022], provided by John Durban and Holly Fearnbach.

Order Artiodactyla Montgelard, Catzefils and Douzery, 1997

 Cetacea Brisson, 1762

   Odontoceti Flower, 1867

     Superfamily Delphinoidea Flower, 1865

       Family Delphinidae Gray, 1821

Orcinus rectipinnus (Cope in Scammon, 1869)

Etymology: In Latin, recti means right or upright, and pinna means fin, feather or wing, most likely referring to the tall, erect dorsal fin of males.

Synonymy: Orca rectipinna Cope in Scammon, 1869: 22; original designation.

Common name: We propose continued use of the common name, ‘Bigg’s killer whale’, for this species, to honour Dr. Michael A. Bigg (1939–1990), who pioneered the study of North Pacific killer whales in the 1970s. This ecotype was formerly known as the ‘transient killer whale’.

Orcinus ater (Cope in Scammon, 1869)

Etymology: In Latin, ater means black or dark, which probably refers to the largely black colour of this species.

Synonymy: Orca ater Cope in Scammon, 1869: 22; original designation.

Common name: We are planning on engaging with North American Indigenous tribal groups and expect to eventually have a consensus common name, but in the meantime, we suggest continued use of ‘resident killer whale’ so as to maintain consistency.

 

Phillip A. Morin, Morgan L. McCarthy Charissa W. Fung, John W. Durban, Kim M. Parsons, William F. Perrin, Barbara L. Taylor, Thomas A. Jefferson and Frederick I. Archer. 2024. Revised Taxonomy of eastern North Pacific Killer Whales (Orcinus orca): Bigg’s and Resident Ecotypes deserve Species Status. R. Soc. Open Sci. 11: 231368. DOI: 10.1098/rsos.231368

 twitter.com/EmmaLuck22/status/1772915048337347033

[PaleoIchthyology • 2023] Rhamphoichthys taxidiotis • The First articulated Skeletons of enigmatic Late Cretaceous Billfish-like Actinopterygians (Tselfatiiformes: Plethodidae)

 Rhamphoichthys taxidiotis

El Hossny, Cavin, Kaplan, Schwermann, Samankassou & Friedman. 2023

 

 DOI:10.1098/rsos.231296 

 twitter.com/Lionel_Cavin

Artwork by Sky Jung.

 

Abstract

Only few candidates of Mesozoic fishes with a similar body plan and ecological niche to the modern billfishes are suggested as their analogues. Several specimens were recovered from Cenomanian deposits in Germany and Lebanon and display a billfish-like fusiform body with elongated premaxillae. They are found close to the plethodids and show a unique combination of characters (rostrum pointed and extremely elongated, double articular head of the quadrate, anteroposteriorly elongated abdominal centra indicating a slender body and different types of scales on the body) allowing their inclusion in a new genus. Two ‘Protosphyraena’ species are also assigned to this new genus. This fish can be considered as an ecological analogue to the extant xiphioids sharing their feeding habits. This fish was abundant and roamed, as an apex predator, the Central Tethys and the Boreal realms during the Cenomanian.

Keywords: ecological analogue, Cenomanian, billfishes, Protosphyraena, Plethodidae, Rhamphoichthys taxidiotis

 

 Cranial anatomy of  Rhamphoichthys taxidiotis gen. et sp. nov., holotype WMNM P 48342.
(a) Photograph of the skull in left lateral view. (b) Interpretive line drawing of (a).

Ang-rart, angulo-retroarticular; Ao, antorbital; Art, articular; Asp, autosphenotic; Br.r, branchiostegal rays; Ce.a, anterior ceratohyal; Cl, cleithrum; Cor, coracoid; Den, dentary; d.f, dilatator fossa; Dsp, dermosphenotic; Ecp, ectopterygoid; Enp, endopterygoid; Fr, frontal; Hm, hyomandibular; Io, infraorbitals; Mes, mesethmoid; Mpt, metapterygoid; Mx, maxillary; Na, nasal; Op, operculum; Ors, orbitosphenoid; Pa, parietal; Par, parasphenoid; Pmx, premaxillary; Pop, preoperculum; Psp, pterosphenoid; Qu, quadrate; Sc.r, sclerotic ring; Sca, scapula; So, supraorbital; Soc, supraoccipital; Sop, suboperclum; Stt, supratemporal; V, vertebrae.

Tselfatiiformes Nelson, 1994 

Plethodidae Loomis, 1900  

Genus: Rhamphoichthys gen. nov.

 

Diagnosis. Elongate plethotid that differs from all others by the combination of the following characters: fusiform body with a slender rostrum making up half the length of the skull; presence of sclerotic ring; a broad and double-headed articular head of quadrate; hyomandibula hourglass shaped; seven broad branchiostegal rays; vertebral column with at least 100 vertebrae (55 abdominal + 40 caudal); abdominal vertebral centra elongate anteroposteriorly; dorsal fin rays very long with some rays exceeding depth of the body; hypural plate large made of fusion of hypurals 1–4 and an autogenous dorsal hypural 5; scales of different types: weakly mineralized ovoid scales, more robustly mineralized rhombic scales, bilaterally symmetrical scales with midline ridge and notch and at least one scale with a serrated posterior margin.

Etymology. From the Greek: rámfos (rhamphos) meaning beak with the suffix ichthys for fish.

Rhamphoichthys taxidiotis sp. nov.

 

Holotype. WMNM P 48342, articulated skull and highly disrupted postcranium.

Horizon. Lowermost horizon of upper Cenomanian of the Hesseltal Formation, Halle, Westphalia, Germany.

Etymology. From the Greek taxidiotis, meaning traveller. The combination makes it ‘the traveller fish with a beak’, reflecting the long rostrum and wide geographical distribution of this presumably pelagic taxon.

 Reconstruction of Rhamphoichthys taxidiotis gen. et sp. nov.

Artwork by Sky Jung.

Tamara El Hossny, Lionel Cavin, Ulrich Kaplan, Achim H. Schwermann, Elias Samankassou and Matt Friedman. 2023. The First articulated Skeletons of enigmatic Late Cretaceous Billfish-like Actinopterygians. R. Soc. Open Sci.10; 231296 DOI:10.1098/rsos.231296

  twitter.com/Lionel_Cavin/status/1732676420197880011

[PaleoMammalogy • 2023] the Pliocene Marsupial Ambulator keanei gen. nov. (Marsupialia: Diprotodontidae) from inland Australia and its Locomotory Adaptations

 Ambulator keanei (Stirton, 1967)

in van Zoelen, Camens, Worthy et Prideaux. 2023.  

DOI: 10.1098/rsos.230211 

 twitter.com/Zoelenotherium

Abstract

Diprotodontids were the largest marsupials to exist and an integral part of Australian terrestrial ecosystems until the last members of the group became extinct approximately 40 000 years ago. Despite the frequency with which diprotodontid remains are encountered, key aspects of their morphology, systematics, ecology and evolutionary history remain poorly understood. Here we describe new skeletal remains of the Pliocene taxon Zygomaturus keanei from northern South Australia. This is only the third partial skeleton of a late Cenozoic diprotodontid described in the last century, and the first displaying soft tissue structures associated with footpad impressions. Whereas it is difficult to distinguish Z. keanei and the type species of the genus, Z. trilobus, on dental grounds, the marked cranial and postcranial differences suggest that Z. keanei warrants genus-level distinction. Accordingly, we place it in the monotypic Ambulator gen. nov. We, also recognize the late Miocene Z. gilli as a nomen dubium. Features of the forelimb, manus and pes reveal that Ambulator keanei was more graviportal with greater adaptation to quadrupedal walking than earlier diprotodontids. These adaptations may have been driven by a need to travel longer distances to obtain resources as open habitats expanded in the late Pliocene of inland Australia.

Keywords: megafauna, Pliocene, Australia, fossil marsupials, Diprotodontidae, cranial and postcranial morphology

 

 Reassembled partial skeleton Ambulator keanei (SAMA P54742) with silhouette.

Systematic palaeontology

Class: Mammalia Linnaeus, 1758 

Superorder: Marsupialia Illiger, 1811 

Order: Diprotodontia Owen, 1877  

Superfamily: Diprotodontoidea Archer & Bartholomai, 1978 

Family: Diprotodontidae Gill, 1872 

Genus: Ambulator gen. nov.

 

Ambulator keanei (Stirton, 1967) comb. nov.

 Genus Etymology: ‘Ambulator’ is Latin for ‘walker’. This is in reference to the taxon's many postcranial adaptations that to plantigrade, graviportal walking. The gender of the genus is masculine.

 

 Species etymology: Named for Mr Vincent P. Keane, who provided heavy equipment for the excavations in the Tirari Desert in 1962 conducted by Ruben A. Stirton, Paul F. Lawson, Richard H. Tedford and Michael O. Woodburne. 

 Holotype: SAMA P13844, partial lower mandible with both ascending rami missing; right and left I1; left and right P3; left M1; right M4, partial maxilla containing left M2–M4. Collected by R. A. Stirton in 1962.

 Type locality: Keane Quarry, Lake Palankarinna, South Australia. Palankarinna Local Fauna, 3.9 Ma.

Conclusion: 

We describe the first postcranial material known for Ambulator keanei. This is only the fourth species of post-Miocene diprotodontid for which postcranial material has been described and includes the first three-dimensional description of the footpad morphology for the family. We found that Am. keanei expresses the earliest evidence for specialized graviportal locomotion within diprotodontids, suggesting that it may have been relatively vagile, which may correlate with late Pliocene grassland expansion. We also found evidence that the phalanges of graviportal diprotodontids were not used in weight bearing during locomotion. Systematic comparisons of established diprotodontid taxa indicate that inclusion of postcranial morphology in phylogenetic analyses is needed in order to resolve both species- and the higher-level taxonomy for the Diprotodontidae. Rare, well-preserved skeletal and soft tissue material found in the Main Body of the Tirari Formation indicates considerable potential for discovery of additional material. Future efforts should target collecting more vertebrate material from this formation. This may lead to not only a better understanding of marsupial diversity but a better understanding of the faunal change of Australia through time.

Jacob D. van Zoelen, Aaron B. Camens, Trevor H. Worthy and Gavin J. Prideaux. 2023. Description of the Pliocene Marsupial Ambulator keanei gen. nov. (Marsupialia: Diprotodontidae) from inland Australia and its Locomotory Adaptations. Royal Society Open Science. DOI: 10.1098/rsos.230211 

 twitter.com/Zoelenotherium/status/1663824958848638976

[Invertebrate • 2023] Polycirrus aoandon, P. onibi & P. ikeguchii • Investigating the Diversity of Bioluminescent Marine Worm Polycirrus (Annelida), with Description of Three New Species from the Western Pacific

Polycirrus onibi Jimi, P. aoandon Jimi, & P. ikeguchii Jimi,
 

in Jimi, Bessho-Uehara, Nakamura, Sakata, Hayashi, et Ogoh, 2023

DOI: 10.1098/rsos.230039

Bioluminescence, a phenomenon observed widely in organisms ranging from bacteria to metazoans, has a significant impact on the behaviour and ecology of organisms. Among bioluminescent organisms, Polycirrus, which has unique emission wavelengths, has received attention, and advanced studies such as RNA-Seq have been conducted, but they are limited to a few cases. In addition, accurate species identification is difficult due to lack of taxonomic organization. In this study, we conducted comprehensive taxonomic survey of Japanese Polycirrus based on multiple specimens from different locations and described as three new species: Polycirrus onibi sp. nov., P. ikeguchii sp. nov. and P. aoandon sp. nov. The three species can be distinguished from the known species based on the following characters: (i) arrangement of mid-ventral groove, (ii) arrangement of notochaetigerous segments, (iii) type of neurochaetae uncini, and (iv) arrangement of nephridial papillae. By linking the bioluminescence phenomenon with taxonomic knowledge, we established a foundation for future bioluminescent research development. We also provide a brief phylogenetic tree based on cytochrome c oxidase subunit I (COI) sequences to discuss the evolution of bioluminescence and the direction of future research.

Keywords: Polycirrus aoandon sp. nov., Polychaeta, Polycirrus onibi sp. nov., Polycirrus ikeguchii sp. nov., terebelliformia, bioluminescence

Polycirrus onibi sp. nov.

 Bioluminescence of Polycirrus spp.
 (a, c) Polycirrus onibi sp. nov.; (b, d) Polycirrus aoandon sp. nov.;
(e) in situ observation of Polycirrus spp. (mixture of P. ikeguchii sp. nov. and P. onibi sp. nov., most of them are P. ikeguchii sp. nov.) at Notojima.

Genus Polycirrus Grube, 1850 

[New Japanese name: Hikari-Fusa-gokai-zoku]

Type-species. Polycirrus medusa Grube, 1850 [13].

Polycirrus onibi Jimi, sp. nov.

[Japanese name: Onibi-fusa-gokai]

Diagnosis. Polycirrus with transparent body wall, tentacles with subterminal red spots, mid-ventral groove from segment 3, notochaetae on segments 3–14, neurochaetae on segment 15 and following segments, type II uncini, nephridial papillae in anterior area of parapodia on segments 3–14.

Etymology. The new species name derives from the Japanese yōkai ‘onibi’. Onibi represents the soul of a deceased human or animal, manifested as a floating blue flame. It is often equated with the Will-o'-the-wisp. The blue–purple bioluminescence is reminiscent of this yōkai.

Polycirrus ikeguchii Jimi, sp. nov.

[Japanese name: Ikeguchi-fusa-gokai]

Diagnosis. Polycirrus with transparent body wall, tentacles with subterminal red spots, mid-ventral groove from segment 2, notochaetae on segments 3–19, neurochaetae on segment 17 and following segments, type II uncini, nephridial papillae in anterior area of parapodia, on segments 3–17.

Etymology. The species is named after Mr Shinichiro Ikeguchi. He is the former deputy director of the Notojima Aquarium, and he contributed to the discovery of the luminescence phenomenon of this species.

Polycirrus aoandon Jimi, sp. nov.

[Japanese name: Aoandon-fusa-gokai]

Diagnosis. Polycirrus with orange body wall, tentacles without subterminal red spots, mid-ventral groove from segment 3, notochaetae on segments 3–56, neurochaetae on segment 16 and following segments, type I uncini, nephridial papillae in anterior area of parapodia on segments 3–14.

Etymology. The new species name derives from the Japanese yōkai ‘Aoandon’. Aoandon carries a blue (= Ao in Japanese) lantern (= andon in Japanese). The blue–purple bioluminescence is reminiscent of this yōkai.

 

Naoto Jimi, Manabu Bessho-Uehara, Koji Nakamura, Masahiko Sakata, Taro Hayashi, Shusei Kanie, Yasuo Mitani, Yoshihiro Ohmiya, Aoi Tsuyuki, Yuzo Ota, Sau Pinn Woo and Katsunori Ogoh. 2023. Investigating the Diversity of Bioluminescent Marine Worm Polycirrus (Annelida), with Description of Three New Species from the Western Pacific. Royal Society Open Science. DOI: 10.1098/rsos.230039

 phys.org/news/2023-03-newly-sea-worms-dark-creatures.html

 

[Paleontology • 2023] Ursactis comosa • First Record of Growth Patterns in A Cambrian Annelid

Ursactis comosa

Osawa, Caron & Gaines, 2023

DOI: 10.1098/rsos.221400

 twitter.com/Hatena_O

drawing by Danielle Dufault / Royal Ontario Museum.

 

Abstract

Early annelid evolution is mostly known from 13 described species from Cambrian Burgess Shale-type Lagerstätten. We introduce a new exceptionally well-preserved polychaete, Ursactis comosa gen. et sp. nov., from the Burgess Shale (Wuliuan Stage). This small species (3–15 mm) is the most abundant Cambrian polychaete known to date. Most specimens come from Tokumm Creek, a new Burgess Shale locality in northern Kootenay National Park, British Columbia, Canada. Ursactis has a pair of large palps, thin peristomial neurochaetae and biramous parapodia bearing similarly sized capillary neurochaetae and notochaetae, except for segments six to nine, which also have longer notochaetae. The number of segments in this polychaete range between 8 and 10 with larger individuals having 10 segments. This number of segments in Ursactis is remarkably small compared with other polychaetes, including modern forms. Specimens with 10 segments show significant size variations, and the length of each segment increases with the body length, indicating that body growth was primarily achieved by increasing the size of existing segments rather than adding new ones. This contrasts with most modern polychaetes, which typically have a larger number of segments through additions of segments throughout life. The inferred growth pattern in Ursactis suggests that annelids had evolved control over segment addition by the mid-Cambrian.

Keywords: Burgess Shale, polychaete, development, stem-group annelid, gregarious behaviour, body tagmatization

 Photos of the holotype, ROMIP 66770.1, of Ursactis comosa gen. et sp. nov. from the lower quarried interval of the Tokumm Creek locality. The specimen has 10 chaetigerous segments and stout palps, peristomial neurochaetae, and longer notochaetae on the sixth to ninth segments. It is presumably preserved dorsally.
(a) Composite image of part and counterpart. Squares with dashed lines indicate the area shown in (b–d). (b) Close-up of the first four segments in the part. (c) Close-up of segments 8–10 and the pygidium in the counterpart. (d) Close-up of the head in the counterpart, showing dark patches within the head. Acronyms: ch, chaetae; chP, peristomial chaetae; mo, mouth; pal, palp; pr, parapodium; py, pygidium; numbers following the acronyms denote segments, counting from anterior, excluding peristomium. Scale bars: (a): 5 mm; (b–d): 1 mm.

Distribution of Ursactis comosa gen. et sp. nov. 
 (a) Maps with localities yielding Ursactis indicated by stars. The detailed map comes from the grey area in the general map. (b) Generalized stratigraphic column for the Burgess Shale Formation at the Tokumm Creek locality. The stars and the adjacent numbers represent the locations of two quarried intervals that yielded specimens of Ursactis and the number of specimens collected at each interval, respectively. (c) Outcrop photo of the lower quarried interval; the quarried interval is marked with dashed lines.
 (d–f) Specimens collected from the Collins Quarry on Mt. Stephen (d), the upper interval of the Tokumm Creek locality (e) and the lower interval of the Tokumm Creek locality (f). (d) Ursactis sp., ROMIP 66882. (e) Ursactis comosa, ROMIP 66873. (f) U. comosa, ROMIP 66874.1. Scale bars: (d): 1 mm; (e,f): 5 mm.

Ursactis comosa gen. et sp. nov.  from the lower quarried interval of the Tokumm Creek locality.
 (a) Overview of one of the multiple slabs of ROMIP 66771B, preserving specimens ROMIP 66771.28–48,74,119–121. Squares with dashed lines indicate areas shown in close-up in (b–d). (b) ROMIP 66771.33–42. A cluster of at least 10 specimens. Counterpart to figure 3d. (c) ROMIP 66771.120. A ventrally preserved specimen showing the biramous state of parapodia, posterior longer notochaetae and the mouth. Close-up image of the head and parapodia is in figure 5k. (d) ROMIP 66771.48. An enrolled specimen.

Acronym: ch, chaetae, with numbers denoting the segments, counting from the anterior, except for the peristomium. Scale bars: (a): 5 cm; (b–d): 5 mm.

Systematic palaeontology

Phylum: Annelida Lamarck, 1809.

Ursactis comosa gen. et sp. nov.

 

 Etymology: Ursa for the constellation Ursa Major, and actis, a Greek word for a ray, referring to the species' starry appearance and the clustered occurrence of fossils; comos, a Latin word meaning ‘having long hair,’ for its long capillary chaetae, in particular some notochaetae on segments six to nine.

Locality and stratigraphy: One specimen of Ursactis sp. (figure 1d) comes from the Collins Quarry on Mt. Stephen, Yoho National Park, Kicking Horse Shale Member. All the specimens of U. comosa come from two stratigraphic intervals within the upper part of the Burgess Shale Formation, Cambrian (Miaolingian Series, Wuliuan Stage), Ehmaniella biozone, at the Tokumm Creek locality of the Marble Canyon area, northern Kootenay National Park, British Columbia, Canada.

  Diagnosis for genus and species: Polychaete worm possessing maximum 10 chaetigers, excluding the peristomium, with biramous parapodia yielding simple capillary chaetae. Approximately 8–12 chaetae on each neuropodium and notopodium, and among chaetigers one to eight. The last two chaetigers have approximately five and two chaetae, respectively. Up to five notochaetae on chaetigers six to nine, double the length of other chaetae on the same chaetigers.

Conclusion: 

The known disparity and ecological diversity of Cambrian annelids have expanded in recent years thanks to the discovery of new species, including tube-dwelling forms [Chen, et al., 2020; Nanglu & Caron, 2021] and forms living in symbiosis with other taxa [Nanglu & Caron, 2021]. The clustering behaviour of Ursactis also implies that some polychaetes probably occupied substantial space and resources in some areas, suggesting a greater ecological role in local ecosystems.

The morphology of Ursactis may provide important clues to understanding the developmental patterns of the ancestral annelid. First, the occurrence of longer chaetae on specific segments suggests an early example of simple body tagmatization in annelids. Second, the surprisingly small number of segments and minor variation in segment number in this new polychaete implies that the addition of segments was terminated earlier in ontogeny than in modern polychaetes. Continued study of the modes of growth in fossilized annelids and of post-larval development of extant polychaetes would provide important clues to understanding the evolution of developmental patterns in the Annelida.

  life reconstruction of Ursactis comosa gen. et sp. nov.  

  drawing by Danielle Dufault / Royal Ontario Museum.  

 

Hatena Osawa, Jean-Bernard Caron and Robert R. Gaines. 2023. First Record of Growth Patterns in A Cambrian Annelid. Royal Society Open Science. DOI: 10.1098/rsos.221400

 twitter.com/Hatena_O/status/1651271505442131969

[Paleontology • 2022] Ausichicrinites zelenskyyi • First nearly complete Feather Star (Crinoidea) from the Upper Jurassic of Africa

 Ausichicrinites zelenskyyi

Salamon, Jain, Brachaniec, Duda, Płachno & Gorzelak, 2022

DOI: 10.1098/rsos.220345 

 twitter.com/RSocPublishing 

Abstract

Fossil comatulids, referred to as feather stars, are mostly known from highly disarticulated specimens. A single isolated element (centrodorsal) has been the basis for taxonomic description of a vast majority of fossil comatulids. Here, we report a nearly complete, and thus extremely rare, comatulid from the Upper Jurassic (Tithonian) of the Blue Nile Basin in central western Ethiopia that provides a unique insight into the morphology of comatulid arms and cirri. It is assigned to Ausichicrinites zelenskyyi gen. et sp. nov. and is the first Jurassic comatulid from the African continent. The new taxon shows some similarities with representatives of the Mesozoic Solanocrinitidae but also has close resemblance with the modern family Zygometridae, exclusively known from the Holocene of western Pacific and eastern Indian Oceans. This morphologic similarity is considered to be due to convergence. The first example of pinnule regeneration in a fossil feather star is reported, which reinforces the hypothesis about the importance of predation in the evolution of these crinoids.

Keywords: Africa, comatulids, tithonian, predation, crinoids, Ethiopia

 

 Ausichicrinites zelenskyyi gen. et sp. nov. from the upper part of the Antalo Limestone Formation (....; 2114 m elevation), 21 m above the upper Tithonian calcareous nannofossil-yielding sample 2043b, Ethiopia.
 Scale bar equals 10 mm (a,c,e,f,g) and 1 mm (b,d,h,i). (a,c). Specimen with centrodorsal, arms and cirri ((a) non-whitened, (c) whitened) with magnifications (b,d) of IBr2 articulation (note a ‘dotted’ suture line (red arrows) from the outer surface of the articulation (b) and a fine ridge (red arrows) on the partly exposed facet (d)). (e) Lateral view showing a centrodorsal (non-whitened). (f,g) Tomographic images of slices of the fossil comatulids showing cryptosyzygial articulation at IBr2 (red arrows). (h) Proximal pluricirral (lateral view) and isolated cirri (facet view, blue arrow). (i) Regenerating pinnules consisting of one to three pinnular plates (blue arrows).

Ausichicrinites zelenskyyi gen. et sp. nov.

 

Mariusz A. Salamon, Sreepat Jain, Tomasz Brachaniec, Piotr Duda, Bartosz J. Płachno and Przemysław Gorzelak. 2022. Ausichicrinites zelenskyyi gen. et sp. nov., A First nearly complete Feather Star (Crinoidea) from the Upper Jurassic of Africa. Royal Society Open Science. 9(7);  DOI: 10.1098/rsos.220345

 twitter.com/RSocPublishing/status/1555433736572919810/

[PaleoOrnithology • 2022] More Bones of Leptoptilos robustus from Flores reveal New Insights into Giant Marabou Stork Paleobiology and Biogeography

A possible scene at Liang Bua around 70 000 years ago.
A giant marabou stork Leptoptilos robustus challenges a juvenile Komodo dragon Varanus komodoensis for access to the carcass of a dwarf proboscidean Stegodon florensis insularis while other giant marabou storks, vultures(Trigonoceps sp.) and hominins (Homo floresiensis) look on.

in Meijer, Sutikna, et al., 2022. 

 DOI: 10.1098/rsos.220435

Reconstruction by Gabriel Ugueto. 

   twitter.com/SerpenIllus

Abstract

Liang Bua (Flores, Indonesia) has yielded remains of a faunal community that included small-bodied and small-brained hominins, dwarf proboscideans, Komodo dragons, vultures and giant marabou storks (Leptoptilos robustus). Previous research suggested that L. robustus evolved from a smaller Leptoptilos dubius-like Middle Pleistocene ancestor and may have been flightless. However, analyses of this species' considerably expanded hypodigm (n = 43, MNI = 5), which includes 21 newly discovered bones described here for the first time, reveals that the wing bones of L. robustus were well-developed and this species was almost certainly capable of active flight. Moreover, L. robustus bones are broadly similar to Leptoptilos falconeri remains from sites in Africa and Eurasia, and its overall size range is comparable to fossils attributed to L. falconeri and similar specimens, as well as those of Leptoptilos lüi (China) and Leptoptilos titan (Java). This suggests that a Pleistocene dispersal of L. falconeri into Island Southeast Asia may have given rise to populations of giant marabou storks in this region. As L. robustus and L. titan are the most recent known representatives of these once plentiful giant marabou storks, Island Southeast Asia likely acted as a refugium for the last surviving members of this lineage.

A possible scene at Liang Bua around 70 000 years ago.
A giant marabou stork Leptoptilos robustus challenges a juvenile Komodo dragon Varanus komodoensis for access to the carcass of a dwarf proboscidean Stegodon florensis insularis while other giant marabou storks, vultures(Trigonoceps sp.) and hominins (Homo floresiensis) look on.

Reconstruction by Gabriel Ugueto.  twitter.com/SerpenIllus

Hanneke J. M. Meijer, Thomas Sutikna, E. Wahyu Saptomo and Matthew W. Tocheri. 2022. More Bones of Leptoptilos robustus from Flores reveal New Insights into Giant Marabou Stork Paleobiology and Biogeography. R. Soc. open sci. 9220435220435. DOI: 10.1098/rsos.220435

  twitter.com/SerpenIllus/status/1547210027835998208