Examining the anatomy of the pelagic Nemertean Protopelagonemertes beebei.

Specimens of pelagic Nemerteans are rarely encountered in nature, and thus, their biology and systematics tend to be poorly characterised. Among the 1300 species in Nemertea (commonly known as Ribbon or Proboscis Worms), approximately 100 have been reported from the epi- to bathypelagic zones within the water column, whereas the remainder are primarily benthic in distribution. With the exception of a few species belonging to the Monostilifera, the majority of the pelagic Nemerteans belong to the Pelagica within the suborder Polystilifera. Since the description of Pelagonemertes rollestoni by Henry Nottidge Moseley in 1875 (the first representative of the Pelagica discovered during the Challenger expedition), three major taxonomic monographs have been published on this group of organisms, that of August Brinkmann in 1917, that of Wesley Coe in 1926, and that of Vera Korotkevich in 1955. However, progress in the systematics of pelagic Polystiliferans has been hindered by their rarity, with 52 of the 96 described species of Pelagica being known from a single specimen. Consequently, for many species the degree of intraspecific variation in taxonomic characters has yet to be established. Moreover, taxonomic descriptions have often been based on material that had become markedly distorted or damaged during retrieval from deep waters. As June 2020, there are only four barcode-sequence entries for the Pelagica in the DDBJ/EMBL/GenBank databases to which species names have been tagged. Accordingly, to ensure the correct application of names to pelagic Nemerteans, larger amounts of data should be accumulated with respect to their precise morphology and DNA barcoding sequences, and for as many species/specimens as possible.

As with the case of other pelagic Nemertean taxa, the taxonomy of the Polystiliferan genus Protopelagonemertes is problematic. Traditionally, the number of proboscis nerves has been one of the major taxonomic characters used to distinguish between the three species that constitute this genus; 29 in  Protopelagonemertes hubrechti; 19–21 (varying within a single specimen) in Protopelagonemertes beebei; and 36 in Protopelagonemertes joculatori. However, variations in the numbers of proboscis nerves have been subsequently documented for different specimens identified as Protopelagonemertes hubrechti: 22, 24, 25, and 26 nerves in four specimens collected in the Southeast Atlantic, off South Africa; 26, 27–29, and 30 nerves in three specimens from the Northwest Atlantic, off Nonsuch Island, Bermuda; and 30 nerves in a specimen from Antarctica. In contrast, no further information has been forthcoming with regards to the variability of this character in two additional specimens identified as Protopelagonemertes beebei, which were collected in the Northeast Pacific, off Baja California, and the Northwest Pacific, off the Kuril Islands, respectively. However, the number of proboscis nerves in a specimen from Sagami Bay, Japan, identified as Protopelagonemertes beebei, was found to vary from 19 to 22 (or, seemingly up to 25), thereby indicating that the variation in this character is completely continuous between that which has previously been reported for Protopelagonemertes beebei and Protopelagonemertes hubrechti. Protopelagonemertes joculatori was described based on a single specimen, and accordingly, there is no indication as to the intraspecific variation of this character in this species. Moreover, it seems highly probable that a proportion, if not all, of the previous studies on these specimens have failed to make a distinction between primary and secondary proboscis nerves. Secondary proboscis nerves were first mentioned by Wesley Coe in 1926 for Planktonemertes agassizii; Pelagonemertes joubini; Plionemertes plana; and Proarmaueria pellucida, and have also been referred to as 'small' proboscis nerves for Neoarmaueria laticeps and Neoarmaueria tenuicauda; Balaenanemertes parvula; Chuniella compacta; Nectonemertes tenuis; Obnemertes solida; and Obnemertes maximovi. In 1992 Alexi Chernyshev described 7–8 'large' and 6–8 'small' proboscis nerves in Zinarmaueria platonovae, and subsequently presented a histological photomicrograph of secondary ('false') proboscis nerves in Planktonemertes sp. More recently, Alexi Chernyshev and Neonila Polyakova have presented a confocal laser scanning micrograph image (labeled with phalloidin, 5-HT, and α-tubulin antibodies) for Nectonemertes cf. mirabilis, depicting primary (larger) and secondary (smaller) proboscis nerves. Despite the findings of these previous studies, the distinction between the primary and secondary nerves is not necessarily obvious. In this reguard, Wesley Coe reasoned that the primary nerves represent the true proboscis nerves, given 'the fact that their branches divide the longitudinal muscular layer into the same number of separate bundles'; however, this can equally apply to secondary nerves. Later, Alexi Chernyshev remarked that the primary nerves can be distinguished from secondary nerves based on the fact that the former invariably come into contact with the inner circular muscle layer of the proboscis.

In a paper published in the journal Plankton & Benthos Research on 18 November 2020, Hiroshi Kajihara of the Faculty of Science at Hokkaido University, and Atsushi Yamaguchi of the Faculty of Fisheries Sciences and the Arctic Research Centre at Hokkaido University, describe  a single specimen of an orange pelagic Polystiliferan, approximately 2 cm long and 7 mm wide in the anesthetised state, identified as Protopelagonemertes beebei, was collected between 3.35 and 4.10 pm Japan Standard Time on June 9, 2020, during a research cruise of the training vessel Ushio-Maru,  using a vertical tow of a 80-cm ring net with 63 μm mesh, from a depth of 830 m (20 m above the sea floor) to the surface off the Pacific coast of Hokkaido, northern Japan.

The specimen was acquired by Atsushi Yamaguchi, maintained at 3°C in a 500-mL bottle, and subsequently sent to Hiroshi Kajihara on 13 2020. On arrival at the laboratory, the specimen was anesthetised in magnesium chloride solution isotonic to seawater, during which the proboscis was partially protruded, and subsequently photographed. The posterior end of the body, which was slightly notched along its medial portion in dorsal view, was cut for a few millimeters and fixed in 99% ethanol for DNA extraction. The remainder of the body was fixed in Bouin's fluid for 24 h, dehydrated in 99% alcohol, cleared in xylene, embedded in paraffin, serially sectioned at a thickness of 7 μm, stained using Mallory's trichrome method, and embedded in Entellan New. This voucher specimen has been deposited in the Invertebrate Collection of the Hokkaido University Museum, with the catalogue number 6146.

 

Photographs of Protopelagonemertes beebei (ICHUM 6146), taken of the specimen in an anesthetized state. (A) Entire body, dorsal view. (B) Anterior end of the body, ventral view, showing cephalic furrows (indicated by arrowheads). (C) Posterior end of the body, dorsal view. Scale bars: 5 mm for (A); 1 mm for (B), (C). Kajihara & Yamaguchi (2020).

Histological observation of the proboscis of ICHUM 6146 revealed that the secondary proboscis nerves in this taxon are accompanied by cell bodies, putatively glial cells (or otherwise neuronal perikarya). In contrast, the primary proboscis nerves are devoid of cell bodies and appear to consist exclusively of axonal fibers. Kajihara and Yamaguchi counted 19–23 primary proboscis nerves and 12–16 secondary proboscis nerves in the anterior proboscis chamber in the present material. The number of the primary proboscis nerves in ICHUM 6146 overlaps with that reported for Protopelagonemertes beebei, at 19–21. However, when combined, the number of the primary and secondary nerves in certain portions add up to 36, thereby encompassing the numbers reported for Protopelagonemertes hubrechti and  Protopelagonemertes joculatori. Accordingly, Protopelagonemertes beebei, and possibly Protopelagonemertes joculatori, may be synonymous with Protopelagonemertes hubrechti. Kajihara and Yamaguchi's observations thus prompted them to question the validity of morphological species delimitation in Protopelagonemertes, given that no distinction has been made between primary and secondary proboscis nerves in the original descriptions of the three congeners Protopelagonemertes hubrechti, Protopelagonemertes beebei, and Protopelagonemertes joculatori. In addition, a connection between what is probably a secondary proboscis nerve and the outer circular muscle layer is observed in ICHUM 6146, which is inconsistent with the criterion proposed by Alexi Chernyshev. Hence, with a view toward a more systematic classification of this genus, morphological and molecular data from reliably identified material, ideally from type localities, should be accumulated for each of the nominal species Bathynemertes hubrechti (type locality: North Atlantic), Protopelagonemertes beebei (type locality: off Nonsuch Island, Bermuda), and Protopelagonemertes joculatori (type locality: Banda Sea).

 

Transverse sections of the proboscis anterior chamber of Protopelagonemertes beebei (ICHUM 6146) showing primary (indicated by white arrowheads) and secondary (indicated by black arrowheads) proboscis nerves. (A) Twenty-three primary nerves and 13 secondary nerves. (B) Magnification of #5 and #6 primary and #2 secondary nerves in (A), the latter of which contains putative glial cells. (C) A secondary nerve extending to the outer circular muscle layer. Abbreviation: OCM, outer circular muscle layer of the proboscis. Scale bars: 200 μm for (A); 50 μm for (B); 20 μm for (C). Kajihara & Yamaguchi (2020).

Kajihara and Yamaguchi have confirmed the presence of cephalic furrows in ICHUM 6146, which is probably the first time this feature has been described in the Pelagica. Although the function of these furrows is uncertain, it can be speculated that they may act as chemical or physical receptors, conceivably by perceiving changes in water pressure attributable to vibrations/waves generated by prey and predator species. Cephalic furrows are commonly found in benthic nemerteans and may also be present in pelagic types. However, in pelagic Nemerteans, the epidermis is often dislodged during collection, thereby rendering the detection of cephalic furrows difficult or impossible.

Protopelagonemertes beebei appears to be common in Japanese meso- to bathypelagic waters; for this species, Kajihara and Yamaguchi propose a new Japanese name, dai-dai-oyogi-himomushi. A megablast search at the DDBJ website based on the LC565011 sequence (658 base pairs, cytochrome c oxidase subunit I gene) derived from ICHUM 6146 resulted in a 100% match with AB587263 and HQ848618 which are sequences derived from two specimens collected at a depth of about 1300 m in Sagami Bay. To determine the sequence of LC565011, total DNA was extracted from the ethanol-preserved tissue using a DNeasy Blood & Tissue Kit. Polymerase chain reaction amplification was performed using the primer pair LCO1490/HCO2198 under the following thermal cycling conditions: an initial denaturation at 98°C for 1 minute; followed by 35 cycles of 98°C for 10 seconds, 45°C for 30 seconds, and 72°C for 1 minute; with a final extension at 72°C for 4 minutes. Nucleotide sequencing was carried out using the same primer pair with an ABI BigDye Terminator ver. 3.1 Cycle Sequencing Kit and a 3130 DNA Analyzer.

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Kamuysaurus japonicus: A new species of Hadrosaur from the Late Cretaceous of Hokkaido, Japan.

Hadrosaurs, or Duck-Billed Dinosaurs, were large herbivorous Ornithischian Dinosaurs widespread across Laurasia (Eurasia plus North America; Laurasia split away from the southern continents in the Triassic, the split into North America and Eurasia during the Cretaceous) as well as South America and Antarctica during the Late Cretaceous. They were descended from the earlier Iguanadontids, but with more sophisticated jaws and teeth, which allowed them to chew their food, not by side-to-side motion as in a modern mammal, but by a unique flexion of the upper jaw parts, which moved apart as the lower jaw moved upwards (from which scientists conclude these Dinosaurs must have had lips, unlike any modern relative of the Dinosaurs). The term 'Hadrosauroid' refers to the widest possible grouping of Hadrosaurs, including all animals in the group after their evolutionary split with the Iguanadontids in the Early Cretaceous, whereas the most derived members of the group are split into two subgroups, the Lambeosaurs, which had hollow bony crests, thought to have been used for making sounds, and the Saurolophides, or Hadrosaurines, which either lacked crests or had solid ones.

In a paper published in the journal Scientific Reports on 5 September 2019, Yoshitsugu Kobayashi of the Hokkaido University Museum, Tomohiro Nishimura of the Hobetsu Museum, Ryuji Takasaki of the Department of Natural History and Planetary Sciences at Hokkaido University, Kentaro Chiba of the Faculty of Biosphere-Geosphere Science at the Okayama University of Science, Anthony Fiorillo of the Perot Museum of Nature and Science, Kohei Tanaka of the Graduate School of Life and Environmental Sciences at rhe University of Tsukuba, Tsogtbaatar Chinzorig of the Division of Vertebrate Paleontology at the Institute of Paleontology and Geology of the Mongolian Academy of Sciences, Tamaki Sato of the Department of Astronomy and Earth Sciences at Tokyo Gakugei University, and Kazuhiko Sakurai, also of the Hobetsu Museum, describe a new species of Hadrosaur from the Late Cretaceous Hakobuchi Formation of Hokkaido, Japan.

The Hakobuchi Formation is the uppermost unit of the Yezo Group, which is a part of a Cretaceous to Paleocene forearc basin deposit that outcrops in southern Hokkaido, Japan. The formation consists of alternating layers of fine- to medium-grained sandstone with hummocky cross-stratification, a bedding pattern typically associated with the action of large storms (such as typhoons) below the fair weather wave base, and sandy mudstones lacking cross-stratification and containing glauconite, a mineral considered indicative of outer shelf environments with low sedimentation rates. The unit of the formation which produced the specimen from which the new species is described has been correlated to the lowest Maastrichtian in age, making it about 72 million years old.

The new Hadrosaur species is named Kamuysaurus japonicus, where 'Kamuysaurus' derives from 'Kamuy', a spiritual or divine being in the mythology of the indigenous Ainu people of Hokkaido, plus '-saurus', the Latin term for a Lizard or Reptile, frequently used as a suffix for Dinosaur names, and 'japonicus' indicates that it comes from Japan. The species is described from a single specimen comprising a nearly complete skeleton with the skull and mandible, derived from an outcrop of the Hakobuchi Formation which is considered to represent an outer shelf environment because of the presence of glauconite sandstone and the absence of hummocky cross-stratification. Despite its completeness, some bones are heavily damaged or eroded by a bio-erosion prior to burial.

(a) The holotype skeleton of Kamuysaurus japonicus. (b) Reconstructed skeleton, showing recovered elements. Selected postcranial elements: cervical vertebrae (atlas, axis, and fourth and twelfth cervicals) in left lateral view (c), dorsal vertebrae (first, seventh, and sixteenth dorsals) in left lateral view (d), caudal vertebrae (anterior, middle, and posterior caudals) in left lateral view (e), left scapula (f) and coracoid (g) in lateral view, right sternum in ventral view (h), left humerus in anterior view (i), right ulna and radius in medial view (j), right manus in dorsal view (k), right pelvis in lateral view (l), right femur in anterior view (m), right tibia in anterior view (n), right fibula in lateral view (o), right astragalus and calcaneum, articulated positioned with tibia (p), and right pes in dorsal view (q). All scales are 10 cm except 1 m scale for (b). Abbreviations; ac, acromion process; ast, astragalus; cal, calcaneum; dpc, deltopectoral crest; fi, fibula; icg, intercondylar groove; il, ilium; is, ischium; ltr, lesser trochanter; mc2, metacarpal II; mc5, metacarpal V; mt2, metatarsal II; mt4, metatarsal IV; nc, neurocentrum; od, odontoid; olp, olecranon process; pc, pleurocentrum; pu, pubis; ra, radius; ti, tibia; ul, ulna; vp, ventral process. Kobayashi et al. (2019).

The specimen is assigned as a Hadrosaurine Hadrosaurid with the following unique characters: the midpoint of the quadratojugal notch is positioned at roughly three-quarters of the total length of the quadrate (a bone in the jaw which forms part of the inner ear in Mammals) from the dorsal end, the ascending process of the surangular (bone in the jaw which has been lost in Mammals) is short, and the neural spines of sixth to thirteenth dorsal vertebrae are inclibed forwards. Kamuysaurus japonicus also has a slightly curved primary ridge on the maxillary(upper) teeth, the high average height/width ratio of the dentary (lower) teeth is over 3.30, there is a moderate medial extension of the symphyseal process of the dentary (jawbone), the anterior margin of the coronoid process of the dentary is more developed than the posterior margin, the triangular ventral margin of the anterior process of the jugal as wide as it is high, the palatine articular facet of the jugal (cheekbone) is moderately inclined, the caudal margin of the quadratojugal flange of the jugal is nearly straight, theanterodorsal margin of the prefrontal (bone that forms the upper inside portion of the orbit) along the orbital rim is smoothly curved, sthe quamosal process of the postorbital (bone that forms the upper outside portion of the orbit) terminates anterior to the quadrate cotylus, the nasofrontal sutural surface of the frontal (connection between the frontal bone, which makes up the forhead, and the bones of the snout) is long, the infratemporal fenestra (opening in the skull behind the eye) is subrectangular, there is a weak expansion of deltopectoral crest of the humerus (long bone in the upper arm), the humerus is slender with the humeral shaft being less than 20% as wide as it is long.

Life reconstruction of Kamuysaurus japonicus with a carcass of a Mosasaur, Phosphorosaurus ponpetelegans, a Sea Turtle, Mesodermochelys undulates, and shells of Ammonoids, Patagiosites compressus and Gaudryceras hobetsense, and Bivalves, Nannonavis elongatus on the beach. The individual of Kamuysaurus in the foreground is reconstructed based on the assumption of the presence of a supracranial crest, similar to a sub-adult form of Brachylophosaurus. The individual behind it is reconstructed without the crest. Kobayash et al. (2019).

In order to access the somatic maturity of this individual, the right tibia was thin-sectioned. Tibiae have been often used for osteohistological examination of Hadrosaurs, because they have a thick cortex and therefore preserve a more complete record of the growth. This ontogenetic assessment indicated that this individual had reached its somatic maturity. Reconstruction of the specimen as a quadruped gave an estimated body mass of 5296 kg, while reconstruction as a biped gave a mass of 4087 kg; in both reconstructions the body length is about 8 m and no further significant growth could have been expected if the animal had continued living.

Carcass of Kamuysaurus, floating in the sea, with two Mosasaurs, Mosasaurus hobetsuensis, two Sea Turtles, Mesodermochelys undulates, and four Ammonoids, Pachydiscus japonicus. Kobayashi et al. (2019).

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Berardius minimus: A new species of Beaked Whale from the North Pacific.

Beaked Whales, Ziphiidae, are the second largest group of Toothed Whales in terms of number of species, with 22 species in six genera. Despite this speciousness the group is not well studied, due to their preference for deep water environments and long dive times, which makes them rather hard to study. The genus Berardius currently contains two species, Baird’s Beaked Whale, Berardius bairdii, found in the North Pacific, and Arnoux’s Beaked Whale Berardius arnuxii, found in the Southern Ocean. However, Whalers from Hokkaido, the northernmost of Japan's four main islands, have long recognised two forms of Beaked Whale in the North Pacific, a larger grey form that corresponds to the official description of Baird’s Beaked Whale, and a smaller black form, which might potentially represent a different species.

In a paper published in the journal Scientific Reports on 30 August 2019, Tadasu Yamada of the Department of Zoology at the National Museum of Nature and Science, Shino Kitamura of the Sanriku Fisheries Research Centre, and the Faculty of Fisheries Sciences at Hokkaido University, Syuiti Abe, also of the Faculty of Fisheries Sciences at Hokkaido University, Yuko Tajima, also of the Department of Zoology at the National Museum of Nature and Science, Ayaka Matsuda, again of the Faculty of Fisheries Sciences at Hokkaido University, James Mead of the Division of Mammals at the Smithsonian Institution, and Takashi Matsuishi, once again of the Department of Zoology at the National Museum of Nature and Science, and of the Global Institution for Collaborative Research and Education at Hokkaido University, formally describe the smaller North Pacific Beaked Whalea as a new species of Berardius.

The new species is named Berardius minimus in reference to its smaller size, and is described on  the basis of six specimens found dead either washed up on beaches or floating close to shore around the island of Hokkaido. The species is notably smaller than both other species of Berardius, with the largest specimen observed being only 6.9 m in length, as well as having a shorter, straighter and narrower beak, being darker in colour, almost black, with prominent white spots, and more prone to bites from Cookie-cutter Sharks. The species was found to be genetically distinct from Berardius bairdii, and to have somewhat different skeletal proportions.

Illustrations of (A) Berardius minimus, and (B) Berardius bairdii. The black bars show 1 m. In general appearance, Berardius minimus resembles a small Berardius bairdii with a proportionately shorter beak and more spindle-shaped body, Yoshimi Watanabe in Yamada et al. (2019).

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Allodesmus uraiporensis: A new species of Allodesmine Seal from the Miocene of Hokkaido.

The Allodesmines are an extinct group of Pinnipeds thought to have been closely related to the True Seals, which are known from the Middle-to-Late Miocene of Japan and the Pacific Coast of North America. They were large animals, reaching about 2.5 m in length, and showed sexual dimorphism, with males bigger than the females and having enlarged canine teeth, presumed to have been used in combat with one-another over mating rights. The taxonomy of Allodesmines is somewhat controversial, with some palaeontologists claiming as many as eight species in four genera, while others recognise only five species in a single genus, Allodesmus.

In a paper published in the journal Royal Society Open Science on 16 May 2018, Wataru Tonomori of the Graduate School of Life and Environmental Sciences at the University of Tsukuba, Hiroshi Sawamura of the Ashoro Museum of Paleontology, Tamaki Sato of the Department of Astronomy and Earth Sciences at the Tokyo Gakugei University, and Naoki Kohno, also of the Graduate School of Life and Environmental Sciences at the University of Tsukuba, and of the Department of Geology and Paleontology at the National Museum of Nature and Science, describe a new species of Allodesmine Seal from the middle Miocene Atsunai Formation of Urahoro, on Hokkaido Island, Japan.

The new species is placed in the genus Allodesmus (Tonomori et al. recognise two genera of Allodesmines, Atopotarus), and given the specific name uraiporensis, meaning 'from Urahoro' (Uraiporo is an old form of Urahoro, itself meaning 'place where big Fish gather' in the Ainu language. The species is described from a single disarticulated but largely complete male specimen, differentiated from all other members of genus by its dentition and structure of the skull. 

Reconstruction of Allodesmus uraiporensis skeleton. Blue parts indicate preserved bones. Tonomori et al. (2018).

With an estimated age of between 16.3 and 13.5 million years old, Allodesmus uraiporensis, is the oldest known member of the genus from the West Pacific, and may represent the earliest arrival of the genus on this side of the ocean, during the Miocene Climatic Optimum (a period of warmth and stability lasting from about 18.0 million years ago till about 14.8 million years ago), which then resulted in an adaptive radiation in the West Pacific, which resulted in several new species.

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Magnitude 6.7 Earthquake off the south coast of Hokkaido Island, Japan.

The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 6.7 Earthquake at a depth of 50 km off the south coast of Hokkaido Island, slightly before 12.30 pm Japan Standard Time (slightly after 3.30 am GMT) on Thursday 14 January 2016. There are no reports of any damage or injuries associated with this event, though it was felt as far south as Tokyo.

The approximate location of the 14 January 2016 Hokkaido Earthquake. Google Maps.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Eastern Honshu area lies on the boundary between the Pacific, Eurasian and Philipine Plates, where the Pacific Plate is passing beneath the Eurasian and Philippine Plates as it is subducted into the Earth. This is not a smooth process; the rocks of the two plates constantly stick together, only to break apart again as the pressure builds up, causing Earthquakes in the process.

The movement of the Pacific and Philippine Plates beneath eastern Honshu. Laurent Jolivet/Institut des Sciences de la Terre d'Orléans/Sciences de la Terre et de l'Environnement.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organization Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Magnitude 5.7 Earthquake off the east coast of Honshū Island, Japan.                              The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 5.7 Earthquake at a depth of 50 km off the coast of Iwate Prefecture, slightly after 1.45 pm Japan Standard Time (slightly after 4.45 am GMT) on Tuesday 17 February 2015. There...

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Phosphorosaurus ponpetelegans: A new species of Halisaurine Mosasaur from the Late Cretaceous of Hokkaido.

Mososaurs were a distinctive group of large marine Squamates (i.e. members of the same group of animals as Lizards and Snakes) that came to dominate many marine ecosystems during the last 20 million years of the Cretaceous. The Halisaurines are considered to be less advanced than other Mososaurs, and least well adapted to a life in open marine waters. They were small for Mososaurs, but still typically reached 4-6 m in length, and have been recorded from North and South America as well as Europe and Africa.

 

In a paper published in the Journal of Systematic Palaeontology on 7 December 2015, Takuya Konishi of the Royal Tyrrell Museum of Palaeontology and Department of Biological Sciences at the University of Cincinnati, Michael Caldwell of the Department of Biological Sciences and Earth and Atmospheric Sciences at the University of Alberta, Tomohiro Nishimura and Kazuhiko Sakurai of the Hobetsu Museum and Kyo Tanoue of Fukuoka University describe a new species of Halisaurine Mosasaur from the Late Cretaceous Hakobuchi Formation of southern Hokkaido Island, Japan.

The new species is placed in the genus Phosphorosaurus, which has previously been described from Belgium, and given the specific name ponpetelegans, meaning 'elegant creek': the specimen from which the species is described comes from a siderite nodule found at Pankerusano-sawa Creek, the specimen is exceptionally well preserved and the creek is noted for its clear water, in addition the specimen was found close to the village of Hobetsu, the name of which also means 'creek'. The specimen comprises a partial skull, reconstructed as being about 500 mm in length, disarticulated but not compressed and largely complete but with some missing elements, plus a fragmentary lower jaw and several neck vertebrae.

Reconstructed skull of Phosphorosaurus ponpetelegans in lateral view. Konishi et al. (2015).

The eye sockets of Phosphorosaurus ponpetelegans are exceptionally large, and interpreted by Konoshi et al. as having given the living animal good binocular vision, with the eyes having a visual field overlap of 35°, larger than in any known Lizard or in any Mososaur for which it has been possible to make such a reconstruction, and towards the upper end of that found in Snakes. Among Snakes a higher visual field overlap tends to be associated with nocturnal species, and a large eye size is also a trait typical of animals of any type which hunt at night (or otherwise in poor light), 

The Hakobuchi Formation has previously produced larger, non-Halisaurine Mosasaurs, which are interpreted as having been piscavores (Fish-eaters) capable of chasing down large prey. It has also produced Lanternfish and Coleoid Cephalopods, groups that today are typically bioluminescent, living in the depths of the ocean below the photic zone (the depths to which sunlight penetrates) during the day, but migrating upwards at night to feed. This leads Kinishi et al. to speculate that Phosphorosaurus ponpetelegans may have been a nocturnal predator, targeting these species and occupying a separate ecological niche to the larger Mososaurs present.

Reconstruction of Phosphorosaurus ponpetelegans as a nocturnal predator. Tatsuya Shinmura/Ashoro Museum of Paleontology/Natural History Museum in  Konishi et al. (2015).

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Aristonectine Elasmosaur remains from the Late Cretaceous of Angola.                                   The Aristonectines were a group of poorly understood Elasmosaurs (long-necked Plesiosaurs) known from the Late Jurassic of the...

Redescription of a Thalattosuchian Crocodyliform from the Jurassic-Cretaceous boundary of Patagonia.                                Purranisaurus potens is known from a single partial specimen from...

A new Placodont specimen from the Late Triassic of Switzerland.                                Psephoderma alpinum is an armoured Placodont (a group of Marine Reptiles known only from the Triassic and thought to be related to Plesiosaurs) known from a number of locations in the Alps. It has a long...

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Changes in the diet of Brown Bears on Hokkaido.

Expanding Human populations have been the major factor affecting almost all of the Earth’s ecosystems since the end of the last glaciation. Human activity has altered food webs on every continent, led to the extinction of many species of animals and plants, with larger animals particularly adversely affected, and altered climates on a regional and increasingly global scale. Brown Bears, Ursus arctos, are highly adaptable large omnivores found across much of the Northern Hemisphere. They are extremely flexible in their dietary habits, and able to change their diet in response to Human or other environmental pressures in ways that few other large animals can manage. Reconstructing the diets of past populations of Brown Bears therefore offers the potential insight into wider impacts on the environment and food chain.

In a paper published in the journal Nature Scientific Reports on 17 March 2015, a team of scientists led by Jun Matsubayashi of the Center for Ecological Research at Kyoto University and the Laboratory of Forest Ecosystem Management at Hokkaido University describe the results of a series of tests on stable isotope ratios from Brown Bear collagen extracted from bone samples from archaeological sites on Hokkaido Island.

A Brown Bear eating a Salmon on Hokkaido. Masaaki Kadosaki/Hokkaido Wildlife Laboratory.

To establish a comparison Matsubayashi et al. established stable isotope levels for potential food sources for Brown Bears on Hokkaido; Herbs, Fruits, Corn, Terrestrial Animals (primarily Sika Deer, Cervus nippon) and Salmon (Chum Salmon, Oncorhynchus keta, and Pink Salmon, Oncorhynchus gorbuscha). These levels were then compared to stable isotope levels from the Bear collagen, in order to try to reconstruct the diets of the living Bears.

The Bear samples were split into two groups, for East and West Hokkaido, where development has proceeded at different rates and where environmental conditions are somewhat different. West Hokkaido is closer to the other islands of Japan and has been intensively settled for longer. It is home to Chum Salmon, which migrate upriver from October to February, and has had a low Deer population throughout the study period. East Hokkaido has been intensively settled and developed only since the mid nineteenth century. It is home to both species of Salmon, with the Chum Salmon migrating upriver from October to February and the Pink Salmon migrating upriver from August to October as well as having had higher Deer populations throughout most of the study period.

The locations of Hokkaido Island and each archaeological sites. Matsubayashi et al. (2015).

The Bear samples were also split into three time periods; Predevelopment (before 1890 in the west and before 1920 in the east), Early Development (1931-1942) and Post Development (after 1996), and the contribution of each dietary source to the isotope ratio in the Bear collagen from each period was estimated.

Bears on the west of Hokkaido consumed high levels of Deer and Salmon in the Predevelopment phase, but had switched to a diet comprising almost entirely Herbs and Fruits by the Early Development phase. Bears on the east of the Island also began with a diet rich in Deer and Salmon, and had largely dropped Salmon from their diet by the Early Development phase. These Bears were still consuming relatively high levels of Deer in the Early Development phase, but again had largely switched to a diet of Herbs and Fruits by the Post Development stage.

Salmon is a highly prized dietary component for Brown Bears, and the Bears would be predicted to use this food source for as long as it is available. Salmon populations are known to have crashed due to overfishing in the late nineteenth century, but recovered during the twentieth century. The failure of Bears to re-adopt Salmon as a major dietary component with recovering populations suggests that the loss of this item from their diet was driven by some factor other than the Salmon population. Matsubayashi et al. suggest that the main factor in determining Bear access to Salmon might be levels of development along river systems, particularly the lower parts of these systems, which are the preferred Salmon-fishing grounds for Brown Bears, but also the first places settled and developed by Humans. Many of these areas were covered by environments that Bears tend to avoid, such as urban areas, paved roads and intensive farmland early in the development of the island, potentially excluding the Bears from their former feeding grounds.

Deer populations also underwent a crash at the end of the nineteenth century, driven by overhunting and two periods of severe snowfall, but again recovered during the twentieth century. Unlike Salmon, Deer occupy essentially the same terrestrial environment as Bears, and therefore human development, unless completely excluding either or both species, cannot be directly responsible for the loss of this food source from the Bear’s diet. Instead Matsubayashi et al. suggest that this might be connected to the extinction of the Hokkaido Wolf (Canis lupus hattai), which died out at the end of the nineteenth century, due to a combination of overhunting and the crash in the population of Sika Deer, its main food species. While Bears will occasionally hunt and bring down Deer, they are not well adapted to this behaviour, and studies in other part of the world have suggested that most of the meat they consume comes from chasing other predators, particularly Wolves, off their kills. If this relationship also formerly existed on Hokkaido, then the loss of Deer from the Diet of Brown Bears there can be directly attributed to the extinction of the Wolves.

See also…

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