ATURIA: MIOCENE NAUTILOID

Aturia angustata, Lower Miocene, WA

This lovely Lower Miocene nautiloid is Aturia angustata collected on the foreshore near Clallam Bay, Olympic Peninsula, northwestern Washington. 

Aturia is an extinct genus of Paleocene to Miocene nautiloid within Aturiidae, a monotypic family, established by Campman in 1857 for Aturia (Bronn, 1838), and is included in the superfamily Nautilaceae (Kümmel,  1964).

There are seven living nautiloid species in two genera: Nautilus pompilius, N. macromphalus, N. stenomphalus, N. belauensis, and the three new species being described from Samoa, Fiji, and Vanuatu (Ward et al.). We have specimens of fossil nautiloids dating to the Turonian of California, and possibly the Cenomanian of Australia. There has also been a discovery of what might be the only known fossil of Allonautilus (Ward and Saunders, 1997), from the Nanaimo Group of British Columbia, Canada.

Aturia in the Collection of Rick Ross, VIPS

The exquisite shell preservation of many Nanaimo nautilids has opened up a lens into paleotemperatures and accurate Nitrogen isotope analyses. 

Nautilus and all other known Cretaceous through Paleogene nautiloids were shallow water carnivores. We may see their shells as beautiful bits of art and science today, but they were seen in our ancient oceans as small yet mighty predators. Preferring to dine on shrimp, crab, fish and on occasion, a friendly cousin nautiloid to two.

Aturia lived in cooler water in the Cenozoic, preferring it over the warmer waters chosen by their cousins. Aturia, are commonly found as fossils from Eocene and Miocene outcrops. That record ends with their extinction in the late Miocene. This was a fierce little beast with jaws packed with piranha-like teeth. They grew at least twice that of the largest known Nautilus living today. 

Aturia is characterized by a smooth, highly involute, discoidal shell with a complex suture and subdorsal siphuncle. The shell of Aturia is rounded ventrally and flattened laterally; the dorsum is deeply impressed. The suture is one of the most complex within the subclass Nautiloidea. Of all the nautiloids, he may have been able to go deeper than his brethren.

Nautiloids are known for their simple suturing in comparison to their ammonite cousins. This simplicity of design limited their abilities in terms of withstanding the water pressure experienced when several atmospheres below the sea. Nautiloids were not able to compete with their ammonite cousins in this regard. 

Instead of elaborate and complex sutures capable of withstanding the pressures of the deep, nautiloids have simpler sutures that would have them enfold on themselves and crush at depth.  

Aturia angustata; Rick Ross Collection

It has a broad flattened ventral saddle, narrow pointed lateral lobes, broad rounded lateral saddles, broad lobes on the dorso-umbilical slopes, and a broad dorsal saddle divided by a deep, narrow median lobe. 

The siphuncle is moderate in size and located subdorsally in the adapical dorsal flexure of the septum. Based on the feeding and hunting behaviours of living nautiluses, Aturia most likely preyed upon small fish and crustaceans. 

I've found a few of these specimens along the beaches of Clallam Bay and nearby in a local clay quarry. I've also seen calcified and chalcedony — microcrystalline quartz — agatized beauties of this species collected from river sites within the Olympic Peninsula range. In the bottom photos, you can see Aturia from Washington state and one (on the stand on the left) from Oregon, USA. These beauties are in the collections of the deeply awesome Rick Ross, Vancouver Island Palaeontological Society.

References: Ward, P; Haggart, J; Ross, R; Trask, P; Beard, G; Nautilus and Allonautilus in the Nanaimo Group, and in the modern oceans; 12th British Columbia Paleontological Symposium, 2018, Courtenay, abstracts; 2018 p. 10-11

KHATSAHLANO: A FOREST FIRE IN STONE

In the Field with Vancouverite Geoscientist Andy Randell — We were super excited to spend a day with the awesome possum that is Andy Randell filming fossils in the field.

We braved the wet and cold on this fine day to head out in search of fossil plants along the Kitsilano foreshore.

And find them we did! 40 million-year-old pretty as you please plant fossils

The Kitsilano fossil plant sites are intriguing as they hold a mystery... why ONLY plants and NO animal fossils? Nary an insect, mammal or reptile to be found. 

We did find some truly lovely plant fossils that speak to a warmer, wetter environment than the Kitsilano we know today. 

Andy shared that the sediments that lay on the foreshore along Kitsilano Beach are thought to be from the Upper Eocene / Early Oligocene in age (38 to 28 million years old), although opinion varies on the exact age with some folk thinking they may be as much as 40 million-years-old. 

The rocks here are layered in stacks of sand, silt and mudstones associated with a lowland estuarine or deltaic environment. If you look closely, you can see signs of the water meandering into channels and ponds of still water. 

The area would have formed a basin, surrounded by mountains that were drained by rivers into this area. It seems that there are no indications of any marine incursions in the sediment pile, and so the area is assumed to have remained stable for some time.

Plant fossils are common in these beds and are often well preserved. The most common are broadleaved deciduous species such as beech, oak, chestnut and hazel, although several coniferous species are known including redwoods (Sequoia), larch, pine and spruce. The deciduous trees like low, moist landscapes which fit with the basin model. The coniferous species likely lived on the surrounding hills where the ground was somewhat drier and their remains transported by rivers into the depositional basin.

There are also regular signs of burning in the fossils – indicating some kind of forest fire events that must have occurred with some frequency.

You will want to catch his wonderfully engaging interviews. Andy is a professional geologist living in Vancouver who is tailoring his career to bring change to the minerals exploration industry. 

Since 2014, he has established his consulting business, SGDS Hive, which takes on graduate geoscientists and mentors them through a variety of exploration projects to help engage and educate the next generation of geologists. 

Andy is the engine behind Below BC, a non-profit society that provides outreach to the public around Earth Science topics, which now serves several thousand people in British Columbia each year. 

His love of geology and palaeontology started early. Andy is a wealth of knowledge on fossil plants. Growing up on the Isle of Wight, he studied plants that are remarkably similar to those we looked at today—and he is a natural behind the lens!

We were joined by my good friend Lauren, the deeply awesome John Fam, Vice-Chair of the Vancouver Paleontological Society & his two boys, Oliver & Liam. 

It was Liam's first fossil field trip & my 7-month old Flat Coat Retriever's first foray into the field. Both Liam and Coco had a grand time! He found fossils that she inspected and on occasion took a wee bite of to see what all the fuss was about.

We were blessed to have David, Andy's partner, teacher & botany buff, along with their two palaeo puppers — Daisy & Dobby — to complete our escort.

With Andy's guidance, everyone found fossil material and learned a lot about how these fossils were originally laid down in a river system.

A huge thank you to Gabriel Mesquita our talented cinematographer! It was a cold, wet day and the entire crew were troopers. If you are planning to visit the Kitsilano foreshore to look for fossils, know that the stairwell access at the base of Dunbar/Alma Street has been washed away. 

You'll want to head to Waterloo Street and make your way to the beach on the rather steep stairwell found there. Surface collecting is fine at this site. Wear rubber boots and know that the rock is very slippery.