Paul A Johnston

• Professor at Mount Royal University

Pre-mortem Trypanites borings in Devonian palaeotaxodonts indicate the anatomical postero-dorsal area of the shell as well as the orientation of the animal within the substrate during life.

In a classic study of bivalves from the Upper Ordovician (Katian) Boda Limestone, Sweden, Isberg (1934) named and described 18 species of the unusual bivalve Shaninopsis, all from the same locality. Our study of the type material indicates that only three species at most are present: Shaninopsis prona Isberg, 1934, Shaninopsis radiata Isberg, 1934,...

Yunfuconcha bimenta, a new genus and species of bivalve from the Ordovician of western Guangdong, China, is described. Its unusual hinge consists of a palaeotaxodont-like dentition anteriorly and a heteroconch-like dentition posteriorly. The posterior hinge area exhibits a remarkable, broad, deeply inset, concave ligament area, which is reminiscent...

Fault-controlled, hydrothermal dolomitization often occurs at margins between shallow-water carbonate platforms and deep-water sedimentary basins. In western Canada, for example, the platform margin between the Cathedral Formation and the Burgess Shale Formation has been dolomitized at temperatures up to ~200 °C, with local magnesite, talc, and cli...

The Upper Ordovician bivalve Shaninopsis Isberg, 1934 is re-examined and shown to be most closely related to the middle Paleozoic Lunulacardiidae (Subclass Cryptodonta).

Using U-Pb geochronology, dolomitization and associated mineralization of the carbonate platform adjacent to the Middle Cambrian Burgess Shale are shown to be syn- to early post-depositional.

The Cryptodonta are documented from the Ordovician to the end-Cretaceous.

In a classic study of bivalves from the Upper Ordovician (Katian) Boda Limestone, Sweden, Isberg (1934) named and described 18 species of the unusual bivalve Shaninopsis, all from the same locality. We examined the type material and, based on morphologic and morphometric analyses, conclude only one species is present, Shaninopsis prona Isberg, 1934...

Our 1998 paper titled "The Bivalve Heresies-Inoceramidae are Cryptodonta, not Pteriomorphia" reclassified a major Mesozoic bivalve group at the subclass level. Our attempt to rehabilitate the Cryptodonta, first described by Neumayr in the 1890's, was based on data and observations that find support in new observations and papers on various cryptodo...

The paleo-ecological settings of Burgess Shale-type (BST) fossils have been the subject of extensive investigations, particularly with regard to the role of anoxia in their exceptional preservation. Our understanding of the complexity of both paleontological and geochemical environmental proxies has evolved with increased knowledge of niche communi...

The paleo-ecological settings of Burgess Shale-type (BST) fossils have been the subject of extensive investigations, particularly with regard to the role of anoxia in their exceptional preservation. Our understanding of the complexity of both paleontological and geochemical environmental proxies has evolved with increased knowledge of niche communi...

The famous middle Cambrian Burgess Shale was deposited abutting an alleged, near vertical, seafloor carbonate cliff known as the Cathedral Escarpment. The Escarpment is thought to have formed from massive failure of the Cathedral carbonate platform margin resulting in a slide surface with a sub-vertical headwall up to 200 m high. Subsequent retrogr...

Bulk sampling of middle Cambrian carbonate units in the lower Burgess Shale Formation (Wuliuan) and the upper Wheeler Formation (Drumian) in Utah have yielded abundant silicified stenothecoids. Previously unreported from the Burgess Shale, stenothecoids discovered include at least two species: Stenothecoides cf. elongata and Stenothecoides rasettii...

Lower to Middle Cambrian strata, well exposed in imbricated westward-dipping thrust sheets of the southern Canadian Rockies, host a range of geologic features from famous fossil lagerstätten to economically important ore deposits. This paper describes six localities in the Front and Central ranges west of Calgary that record tectonic, sedimentologi...

The following classification summarizes the suprageneric taxonomy of the Bivalvia for the upcoming revision of the Bivalvia volumes of the Treatise on Invertebrate Paleontology, Part N. The development of this classification began with Carter (1990), Campbell, Hoekstra, and Carter (1995, 1998), Campbell (2000, 2003), and Carter, Campbell, and Campb...

An unusually large specimen of the rare digitate to bladed Aulocopella winnipegensis Rauff and three relatively normal sized specimens of ashtray-shaped Hudsonospongia? sp. constitute the first record of demosponges from the Upper Ordovician Beaverfoot Formation in southeastern British Columbia and the first record of these taxa from western Canada...

Small egg-like structures from the Upper Cretaceous (Campanian) Djadokhta Formation of Mongolia were previously interpreted as casts of crocodile, lizard, and turtle eggs, or as inorganic nodules. Identical structures from coeval redbeds at Bayan Mandahu in northern China indicate the structures are not vertebrate eggs, nor of vertebrate origin. Co...

Because the Bayan Mandahu redbeds of Inner Mongolia share similar sedimentary facies and fossil assemblages with the Djadokhta Formation of pre-Altai Gobi, the two units are interpreted as stratigraphic correlatives, both of Campanian age. Sedimentary facies indicate that the Bayan Mandahu redbeds were deposited in semiarid, alluvial to eolian envi...

Until recently, research on the renowned fossil animals of the Burgess Shale has advanced to a greater degree than an understanding of the rocks in which they are found. Studies addressing lithostratigraphy and hydrothermal petrography of the so-called ‘inner carbonate belt’ and adjacent Chancellor Group, however, have begun to re-evaluate long-sta...

The Monarch, a mountain in southeastern British Columbia, exposes the Cathedral Escarpment, which abuts the basinal Burgess Shale and an underlying limestone, the upper Takakkaw Tongue. At one section, a dolomitized megabreccia, representing an intraformational collapsed cavern, forms the Cathedral Escarpment wall. The megabreccia is cross-cut by t...

A newly discovered Burgess Shale-type (BST) biota occurs in southeastern British Columbia on Haiduk and Tangle peaks. The fossiliferous rocks of the informally named Vermilion sub-unit and Duchesnay unit occur in the Bolaspidella Zone, one trilobite biozone younger than the Burgess Shale Formation. The younger rocks abut the Eldon Escarpment in a s...

Middle Cambrian basinal strata along the Kicking Horse Rim, including the Burgess Shale Formation, con- tain lenses of black, thin-bedded, noncalcareous, geochemically anomalous chloritic rock. The lenses have ex- tremely high MgO concentrations (up to 31 wt %), or less commonly are enriched in Ba (up to 1,680 ppm), which contrasts with surrounding...

The Kicking Horse Rim is a linear, fault-controlled, paleotopographic high over which the seaward edge of platformal strata repeatedly developed during the Middle Cambrian. Shale-dominated slope deposits along the Kicking Horse Rim, including the Burgess Shale Formation, contain lenses of black, thin-bedded, non-calcareous, geochemically-anomalous...

Megafossils show an unusual distribution within the Burgess Shale Formation and the younger Vermilion and Duchesnay units of the Chancellor Group in southeastern British Columbia. Within the Burgess Shale, concentrations of fossils are restricted to a narrow linear zone (<50 m wide) where the shale abuts the Cathedral Escarpment, a submarine cliff...

Deciphering the oxygenation potential of bottom waters during deposition of the fossiliferous strata of the Burgess Shale is key to understanding the paleoecology of the organisms preserved as fossils and the processes involved in their preservation. Methods of paleo-redox determination that are based upon trace fossils, organic carbon content, or...

Conical and flat-topped hillocks dotting the shale plains near Pueblo are erosional remnants armoured by irregular limestone lenses. Dense lucinid bivalve assemblages and carbonate cements with stable carbon isotope signatures indicative of mineral precipitation in the presence of methane are characteristic of the lenses. Coquinoid limestones compr...

Megafossils show an unusual distribution within the geographically extensive Middle Cambrian Burgess Shale Formation and the younger Duchesnay and Vermilion units of the Chancellor Group, in southeastern British Columbia. Within the Burgess Shale, concentrations of fossils are largely restricted to a narrow linear zone (in our experience typically...

Megafossils show an unusual distribution within the geographically extensive Middle Cambrian Burgess Shale Formation and the younger Duchesnay and Vermilion units of the Chancellor Group, in southeastern British Columbia. Within the Burgess Shale, concentrations of fossils are largely restricted to a narrow linear zone (in our experience typically...

Recent debates concerning the origin of Emsian carbonate mud buildups exposed at Hamar Laghdad in the eastern Anti-Atlas of Morocco centre around geochemical studies that suggest authigenic or chemosynthetic processes induced precipitation of mud from hydrothermal fluids. Geochemical data alone cannot be used to demonstrate conclusively the origin...

New data on shell morphology in praecardioid bivalves support our earlier hypothesis that these bivalves form a natural group and that they constitute a distinct subclass of bivalves: the Cryptodonta. Our results stand in marked contrast to recent published classifications of the Bivalvia in which the Cryptodonta are discarded as a wastebasket taxo...

Aiming to understand lateral variations in faunal composition within the Burgess Shale Formation, we examined exposures 60 km to the southeast of the type area at The Monarch, a mountain straddling the British Columbia/Alberta border. Three sections were studied, including the north and south walls of a cirque (1 km apart) and another section 100 m...

Some worms, arthropods, and other organisms known from the Burgess Shale have been discovered in younger rocks at two new sites in southeastern British Columbia. One of these sites is situated on the south flank of Haiduk Peak and the other occurs near Miller Pass (Fig. 1). The two locales are in outcroppings of the Duchesnay unit (upper Middle Cam...

Field studies in the Middle Cambrian Burgess Shale Formation and Duchesnay Unit (both Chancellor Group, British Columbia) indicate that seeps may have profoundly influenced the composition and distribution of the sediments and biota. Our evidence for seeps includes deposits of iron phyllosilicate ooids, carbonate mud mounds, and the appropriate pal...

The origin of ooidal ironstones remains controversial. Conventional interpretations for their formation include diagenesis of authigenic calcitic ooids or derivation from lateritic precursor materials. Some recent studies have implicated exhalative hydrothermal sources or derivation from volcanic ash. We have examined typical Minette-type ooidal ir...

Faunal composition of the Middle Cambrian Burgess Shale at The Monarch strongly contrasts with that of the type localities at mounts Field and Stephen to the northwest. At The Monarch, shallow-water dolomites of the Cathedral Formation are cut by a megatruncation surface known as the Cathedral Escarpment, a feature continuous for nearly 100 km. A t...

Field studies in the Middle Cambrian Burgess Shale Formation and Duchesnay Unit (both Chancellor Group, eastern British Columbia) indicate that seeps may have profoundly influenced the composition and distribution of the sediments and biota. Our evidence for seeps includes deposits of iron-rich ooids, carbonate mud mounds, and the appropriate paleo...

Widespread in Phanerozoic epeiric depositional environments, ooidal ironstones remain controversial, there being no consensus on their origin. Conventional interpretations for their formation include diagenesis of authigenic calcitic ooids (Alling, 1947) or derivation from lateritic precursor materials (Nahon et al., 1980). Comparisons of Fe-rich p...

During the last decade it has become increasingly clear that Minette-type oolitic ironstones are authigenic deposits rather than products of early burial diagenesis [Kimberley 1994]. Minette-type iron deposits occur throughout the Phanerozoic in shallow-water settings within tectonically active, heavily-faulted regions. They are often associated wi...

A new genus and species of fossil mosquito (Diptera: Culicidae) is described from Canadian Cretaceous amber, thus providing the first undeniable record of this group from the Cretaceous Period. Paleoculicis minutus n.gen., n.sp. can be separated from extant culicids by features of the head, thorax, and abdomen. Paleoculicis has closer affinities to...

The term "monovincular ligament" is introduced.

Retroceramid ligaments and life mode are discussed

ISSN 1183-0298X

This was only the 2nd or 3rd time that Paul Johnston and I had submitted talks at conferences outlining our new thinking on the origin of the Inoceramidae, and the long-maligned bivalve subclass Cryptodonta. Earlier in 1998 the BIVALVIA: AN EON OF EVOLUTION volume had been published (based on the 1995 bivalve meeting at the Tyrrell Museum in Albert...

New data contradict the mosasaur-bite hypothesis for the origin of holes seen in Placenticeras ammonites from the Late Cretaceous Pierre Shale and Bearpaw Formation of the western interior of North America. Observations of a limpet-infested Placenticeras ammonite and of several Placenticeras specimens with radular scratch marks reveal that the limp...

Morphologic and paleoecologic similarities of Inoceramidae and Paleozoic Praecardioidea indicate phylogenetic proximity. The Inoceramidae are therefore removed from the subclass Pteriomorphia and placed with praecardioideans in the subclass Cryptodonta. Comparison of the multivincular ligaments of Inoceramidae and the pteriomorph Isognomon reveal f...

Following our abstract & talk at the Inoceramid Workshop in Freiberg, Germany in 1996, this abstract was only the 2nd Collom & Johnston presentation of our new hypothesis on bivalve phylogeny and taxonomy. It was also the second time we used the term MONOVINCULAR to describe the newly-documented ligamenture of these long-neglected and misunderstood...

Our earliest introduction of the new term MONOVINCULAR LIGAMENT, used to describe the unique ligament of the Cryptodonta (Bivalvia). This is ancestral to the MULTIVINCULAR ligament of the Inoceramidae, which are herein moved from the Subclass Pteriomorphia to the Subclass Cryptodonta.

The northern Rocky Mountain Lower Paleozoic rocks consist of carbonates deposited in the shallow waters of the MacDonald Platform, and the coeval slope and basin facies of the Kechika Trough to the west of the platform. A prominent unconformity is at the base of an Upper Ordovician 'quartzite and dolomite unit'. In a small region east of the main r...

Though long suspected to be critical to the understanding of the evolution of the pelecypod subclass Pteriomorphia, the mid-Palaeozoic family Rhombopteriidae was too poorly known to allow clarification of its relationships. Furthermore, numerous species were assigned to the nominate genus, Rhombopteria , many of which belong in other genera or even...

A well preserved pteriomorphian bivalve from the Middle Silurian of New South Wales is assigned to a new genus and species, Umburra cinefacta, and a new, monotypic family, Umburridae. The Umburridae are included in the Superorder Eupteriomorphia on the basis of the left-convex, inequivalved shell, but show some prionodont features including a conti...

A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves three steps: the dissolution of carbonate in fossiliferous...

The discovery of mammalian fossils in the sandy phase of the Frenchman Formation of Saskatchewan documents the first record of Mesozoic mammals from that province, and from Canada outside of Alberta. Mammals identified include Mesodma (Multituberculata), a didelphid marsupial, a species of Cimolestes (Insectivora) apparently structurally intermedia...

ANNUAL growth rings are often found in the skeletal tissues of Recent and fossil ectothermic vertebrates1,2. These rings are usually attributed to the inability of ectotherms to maintain high levels of activity, feeding and growth during adverse times, such as dry seasons in tropical areas and cold seasons at higher, more temperate latitudes1. In e...