TRILOBITES: HIGHLY SUCCESSFUL ANCIENT ARTHROPODS

Trilobites are an extinct group of marine arthropods that first appeared in the Early Cambrian. They left many beautifully preserved examples of their three-lobed exoskeletons in the fossil record. Trilobites — in all their many wonderful forms — lived in our ancient oceans for more than 270 million years. The last of their lineage went extinct at the end of the Permian, 252 million years ago.  

THE CAMBRIAN EXPLOSION: AN EXPLOSION OF LIFE

TREASURES OF CANADA: TRENT RIVER PALAEONTOLOGY

Dan Bowen, Chair, VIPS, Trent River

The rocks that make up the Trent River on Vancouver Island were laid down south of the equator as small, tropical islands. They rode across the Pacific heading north and slightly east over the past 85 million years to where we find them today.

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. And it is massive. At 103 million km2 (40 million sq mi), it is the largest tectonic plate and continues to grow fed by volcanic eruptions that piggyback onto its trailing edge.

This relentless expansion pushes the Pacific Plate into the North American Plate. The pressure subducts it beneath our continent where it then melts back into the earth. Plate tectonics are slow but powerful forces. 

The island chains that rode the plates across the Pacific smashed into our coastline and slowly built the province of British Columbia. And because each of those islands had a different origin, they create pockets of interesting and diverse geology.

It is these islands that make up the Insular Belt — a physio-geological region on the northwestern North American coast. It consists of three major island groups — and many smaller islands — that stretches from southern British Columbia up into Alaska and the Yukon. These bits of islands on the move arrived from the Late Cretaceous through the Eocene — and continues to this day.

The rocks that form the Insular Superterrane are allochthonous, meaning they are not related to the rest of the North American continent. The rocks we walk over along the Trent River are distinct from those we find throughout the rest of Vancouver Island, Haida Gwaii, the rest of the province of British Columbia and completely foreign to those we find next door in Alberta.

To discover what we do find on the Trent takes only a wee stroll, a bit of digging and time to put all the pieces of the puzzle together. The first geological forays to Vancouver Island were to look for coal deposits, the profitable remains of ancient forests that could be burned to the power industry.

Jim Monger and Charlie Ross of the Geological Survey of Canada both worked to further our knowledge of the complex geology of the Comox Basin. They were at the cutting edge of west coast geology in the 1970s. It was their work that helped tease out how and where the rocks we see along the Trent today were formed and made their way north.

We know from their work that by 85 million years ago, the Insular Superterrane had made its way to what is now British Columbia. 

The lands were forested much as they are now but by extinct genera and families. The fossil remains of trees similar to oak, poplar, maple and ash can be found along the Trent and Vancouver Island. We also see the lovely remains of flowering plants such as Cupanities crenularis, figs and breadfruit.

Heading up the river, you come to a delineation zone that clearly marks the contact between the dark grey marine shales and mudstones of the Haslam Formation where they meet the sandstones of the Comox Formation. Fossilized material is less abundant in the Comox sandstones but still contains some interesting specimens. Here you begin to see fossilized wood and identifiable fossil plant material.

Further upstream, there is a small tributary, Idle Creek, where you can find more of this terrestrial material in the sandy shales. As you walk up, you see identifiable fossil plants beneath your feet and jungle-like, overgrown moss-covered, snarly trees all around you.

Walking west from the Trent River Falls at the bottom, you pass the infamous Ammonite Alley, where you can find Mesopuzosia sp. and Kitchinites sp. of the Upper Cretaceous (Santonian), Haslam Formation. Minding the slippery green algae covering some of the river rocks, you can see the first of the Polytychoceras vancouverense zone.

Continuing west, you reach the first of two fossil turtle sites on the river — amazingly, one terrestrial and one marine. If you continue, you come to the Inland Island Highway.

The Trent River has yielded some very interesting marine specimens, and significant terrestrial finds. We have found a wonderful terrestrial helochelydrid turtle, Naomichelys speciosa, and the caudal vertebrae of a Hadrosauroid dinosaur. Walking down from the Hadrosaur site you come to the site of the fossil ratfish find — one of the ocean's oddest fish.

Ratfish, Hydrolagus Collie, are chimaera found in the north-eastern Pacific Ocean today. The fossil specimen from the Trent would be considered large by modern standards as it is a bruiser in comparison to his modern counterparts. 

This robust fellow had exceptionally large eyes and sex organs that dangled enticingly between them. You mock, but there are many ratfish who would differ. While inherently sexy by ratfish standards, this fellow was not particularly tasty to their ancient marine brethren (or humans today) — so not hugely sought after as a food source or prey.

A little further again from the ratfish site we reach the contact of the two Formations. The rocks here have travelled a long way to their current location. With them, we peel away the layers of the geologic history of both the Comox Valley and the province of British Columbia.

The Trent River is not far from the Puntledge, a river whose banks have also revealed many wonderful fossil specimens. The Puntledge is also the name used by the K'ómoks First Nation to describe themselves. They have lived here since time immemorial. Along with Puntledge, they refer to themselves as Sahtloot, Sasitla and Ieeksun.

References: Note on the occurrence of the marine turtle Desmatochelys (Reptilia: Chelonioidea) from the Upper Cretaceous of Vancouver Island Elizabeth L. Nicholls Canadian Journal of Earth Sciences (1992) 29 (2): 377–380. https://doi.org/10.1139/e92-033; References: Chimaeras - The Neglected Chondrichthyans". Elasmo-research.org. Retrieved 2017-07-01.

Directions: If you're keen to explore the area, park on the side of Highway 19 about three kilometres south of Courtenay and hike up to the Trent River. Begin to look for parking about three kilometres south of the Cumberland Interchange. There is a trail that leads from the highway down beneath the bridge which will bring you to the Trent River's north side.

FERRISAURUS SUSTUTENSIS: A NEW NON-AVIAN DINOSAUR IN BC

Say hello to Ferrisaurus sustutensis —  “A new leptoceratopsid dinosaur from Maastrichtian-aged deposits of the Sustut Basin, northern British Columbia, Canada."

You may recall Dr. Victoria Arbour, curator of palaeontology at the Royal BC Museum from her work on ankylosaurs & that interesting specimen from Hornby Island thought to be a pterosaur but further study revealed to be a saurodontid fish, an ambush predator with very sharp serrated teeth and elongate, torpedo-like body. Not a pterosaur but still a massively exciting find. Arbour was very gracious about the new interpretation, taking it in stride. She has since gone on to name this partial ornithischian dinosaur from Sustut Basin, as well as the ankylosaurs Zuul, Zaraapelta, Crichtonpelta, and Ziapelta. She's been a busy bee.

For this latest find, she’s partnered up & published her findings with David Evans from the Royal Ontario Museum in the peer-reviewed scientific journal PeerJ - the Journal of Life and Environmental Sciences last year. Their paper describes this partial dinosaur skeleton found amongst the inhospitable boreal forests and folded rock of the Canadian Cordillera near the Sustut Basin of northern British Columbia, Canada.

The first bones were collected by geologist Kenny F. Larsen who was surveying for uranium along the then in-construction BC Rail line along the Sustut River. The bones were later donated to Dalhousie University in Halifax, Nova Scotia then accessioned by the Royal British Columbia Museum in Victoria, BC. The skeleton includes parts of the pectoral girdles, left forelimb, left hindlimb, and right pes. Their rationale for a new species distinguished from other named leptoceratopsids is based on the proportions of the ulna and pedal phalanges.

This specimen was previously described in 2008 as an indeterminate small-bodied, bipedal neornithischian, possibly representing either a pachycephalosaur or a basal ornithopod similar to Thescelosaurus. With more material to work with, Arbour and Evans reinterpreted the remains as a leptoceratopsid ceratopsian, Ferrisaurus sustutensis, gen. et. sp. nov.

Figure 2: Preserved elements of RBCM P900

The news deserves some fanfare. While Alberta, our sister province to the east is practically littered with dinosaur remains, they are relatively rare in BC. This is the first unique non-avian dinosaur species reported from British Columbia.

It has been placed, within a reasonably resolved phylogenetic context, with Ferrisaurus recovered as more closely related to Leptoceratops than Montanoceratops. At 68.2–67.2 Ma in age, Ferrisaurus falls between, and slightly overlaps with, both Montanoceratops and Leptoceratops, and represents a western range extension for Laramidian leptoceratopsids. Leptoceratopsidae is an extinct family of neoceratopsian dinosaurs from Asia, North America and Europe. They resembled and were closely related to, other neoceratopsians, such as Protoceratopsidae and Ceratopsidae, but they are more primitive and generally smaller.

Figure 3: Pectoral Elements of Laramidian leptoceratopsids

Back in 2017, Arbour led an expedition to the Sustut River in Northern British Columbia to relocate the site where Ferrisaurus was originally discovered forty-six years earlier in 1971 along the BC Rail line near the intersection of Birdflat Creek and the Sustut River. The expedition was a huge success as the team found the remains of this new species of dinosaur and also recovered several species of fossil plants.

The fossil plant finds may not seem that exciting in comparison to a dinosaur but Cretaceous plants in BC are also relatively rare. Most of our best fossil plant sites are Eocene, the ancient lakebed sites at McAbee and Princeton — so a good 15 million or so years earlier.

During that expedition, the team recovered a fragment of a large Cretaceous terrestrial trionychoid turtle Basilemys from the family Nanhsiungchelyidae near the confluence of Birdflat Creek and the Sustut River. This largely North American turtle along with the plants will allow us to make correlations with terrestrial finds from other sites including those from the Nanaimo group, the inland island construction sites and the Trent River on Vancouver Island and Horseshoe Canyon in southwestern Alberta. Jordan Mallon and Donald Brinkman have done some good work on the Basilemys morrinensis from the Upper Cretaceous Horseshoe Canyon Formation. The Sustut Basin turtle and plant remains have been accessioned into the Royal BC Museum’s collections in Victoria.

It wasn't until last summer that Arbour was able to extract more of this dinosaur and not all of it as their field season was shortened by a cold snap that brought snow and ice, freezing the ground they were working in the high alpine. Arbour plans to continue her work searching for dinosaur fossils in the high alpine plateaus of northern British Columbia. A fresh grant this year from the Natural Sciences and Engineering Research Council of Canada (NSERC) will help pave the way for both her and some summer students to continue their fieldwork.

Reference: Arbour VM, Evans DC. 2019. A new leptoceratopsid dinosaur from Maastrichtian-aged deposits of the Sustut Basin, northern British Columbia, Canada. PeerJ 7:e7926 https://doi.org/10.7717/peerj.7926. Here's a link to the paper: https://peerj.com/articles/7926/

Figure 1: RBCM P900, the holotype of Ferrisaurus sustutensis, was collected along the BC Rail line near the intersection of Birdflat Creek and the Sustut River in 1971, in the Sustut Basin of northern British Columbia, Canada. Map modified from Evenchick et al. (2003).

Figure 2: Preserved elements of RBCM P900, holotype of Ferrisaurus sustutensis, in white (gray represents missing parts of incomplete bones). RBCM P900 includes a partial right coracoid, partial left scapular blade, complete left radius, partial left ulna, partial left tibia, fibula, and coossified astragalus and ?calcaneum, partial left metatarsals I-IV, and digits III (phalanges 2–4) and IV (phalanges 2–5) of the right pes.

Figure 3: Pectoral elements of RBCM P900, holotype of Ferrisaurus sustutensis, compared to other Laramidian leptoceratopsids. (A) Fragmentary right coracoid of RBCM P900 in lateral view, compared to (B) complete right scapulocoracoid of CMN 8889, Leptoceratops gracilis, lateral view centered on coracoid with scapula in oblique view. Fragmentary left scapular blade of RBCM P900 in (C) lateral and (D) medial view, compared to (E) left scapula of MOR 300, Cerasinops hodgskissi in medial view, and (F) left scapula of TCM 2003.1.9, Prenoceratops pieganensis in lateral view. Abbreviations: sp, sternal process.