EOCENE CRYPTODIRAN TURTLE

An Eocene Cryptodiran Fossil Turtle, Baena arenosa, from fine-grained lime mud outcrops in the Green River Formation, Wyoming, USA.

This fellow, with the extra-long tail, marks the last of his lineage. The now extinct family Baenidae appeared first in the Jurassic and died out at the end of the Eocene. We've found specimens of Baena, along with 14 other species of turtles in seven genera and five families in the Lower Eocene San Jose Formation, San Juan Basin of New Mexico.

This specimen is from the Green River Formation of Wyoming which was once the bottom of one of an extensive series of Eocene lakes. The Green River Formation is particularly abundant in beautifully preserved fossil fish, eleven species of reptiles including a 13.5ft crocodile, an armadillo-like mammal, Brachianodon westorum, bats, birds and other fresh-water aquatic goodies.

This specimen of a beautiful Baena was found and prepped by the Green River Stone Company. They purchased their private 12-acre quarry about 20 years ago. It's at the Eocene lake's centre, shared with Fossil Butte National Monument about 24 kilometres (15 miles) west of Kemmerer, Lincoln County, Wyoming.

DESHAYESITES VOLGENSIS BLOCK

From Russia with Love — a lovely iridescent block of ammonites with Deshayesites volgensis (Sasonova, 1958), and Aconeceras (Sinzovia) trautscholdi (Sinzow. 1870) with their natural pink, blue and purple candy colouring. These beauties are from Lower Cretaceous, Aptian, 120 - 112 million-year-old outcrops near Shilovka, Ulyanovsk Region, Russia. This lovely block was collected by and is in the collections of the deeply awesome Emil Black.

Aptian deposits near the Volga River between Ul'yanovsk and Saratov have been studied for more than a century. The age of lower Aptian deposits was traditionally established based on changing ammonite assemblages of the family Deshayesitidae.

The diverse assemblage of heteromorphic ammonites, Ancyloceratidae, inhabitants of relatively deep basins, has made it possible to propose a new scheme of ammonoid zonation in the lower Aptian epipelagic deposits of the Russian plate.

Many of the identified ancyloceratids were established here for the first time. The analysis of coexisting deshayesitids and heteromorphs enabled a correlation of stratigraphic schemes for the monomorphic Deshayesitidae and heteromorphic Ancyloceratidae. The described generic taxa and species are Volgoceratoides I. Michailova et Baraboshkin, gen. nov., V. schilovkensis I. Michailova et Baraboshkin, sp. nov., Koeneniceras I. Michailova et Baraboshkin, gen. nov., K. tenuiplicatum (von Koenen, 1902), K. rareplicatum I. Michailova et Baraboshkin, sp. nov.

In few sections of the Saratov Volga area (central part of the Russian Platform), representing both offshore and nearshore lithofacies of the epicontinental Middle Russian Sea, researchers have recognized simultaneous changes in ammonite and belemnite successions. The significant influence of anoxic events on faunal turnovers in marine communities is well-established. However, many studies are focused on the impact of anoxic conditions on benthic organisms, not on the hunter-gatherers living higher up in the sea column. This means that coeval changes in pelagic cephalopod assemblages remain relatively poorly understood.

Belemnites, represented by the late members of the family Oxyteuthididae, are common in the interval directly preceding the anoxic event, but totally disappear with the onset of the black shale deposition. We see a reduction in the shell size of the Deshayesites ammonites across the mudstone – black shale boundary (maximum shell diameter of adults reduces from ∼20 cm to 7–8 cm).

Some other ammonites become numerous (Sinzovia) within the black shale interval or show the first occurrence in it (Koeneniceras and Volgoceratoides). In our opinion diminishing of Deshayesites shell size during the early Aptian OAE could be caused by the coupling of palaeoenvironmental factors such as progressive warming and regional input of brackish water. Preliminary results of carbon isotope studies of aragonite deriving from the ammonite nacreous layer are also provided.

The significant influence of anoxic events on faunal turnovers in marine communities is well-established. However, many studies are focused on the impact of anoxic conditions on benthic organisms, not on the hunter-gatherers living higher up in the sea column. This means that coeval changes in pelagic cephalopod assemblages remain relatively poorly understood. The maximum diameter on the Deshayesites shown here in the photo by Emil Black is 70 mm.

Rogov, Mikhail & Shchepetova, Elena & Ippolitov, Alexei & Seltser, Vladimir & Mironenko, Aleksandr & Pokrovsky, Boris & Desai, Bhawanisingh. (2019). Response of cephalopod communities on abrupt environmental changes during the early Aptian OAE1a in the Middle Russian Sea. Cretaceous Research. 10.1016/j.cretres.2019.01.007.

E. Yu. Baraboshkin and I. A. Mikhailova. New Stratigraphic Scheme of the Lower Aptian in the Volga River Middle Courses. Stratigraphy arid Geological Correlation, Vol 10, No 6, 2002, pp 603-626 Translated from Stratigrafiy a Geologicheskaya Korrelyatsiya, Vol 10, No 6, 2002, pp 82-105

LATE JURASSIC PHYLLOCERAS

Phylloceras consanguineum (Gemmellaro 1876) a fast-moving carnivorous ammonite from Late Jurassic (Middle Oxfordian) deposits near Sokoja, Madagascar, off the southeast coast of Africa.

This classical Tethyan Mediterranean specimen is very well preserved, showing much of his delicate suturing in intricate detail. Phylloceras were primitive ammonites with involute, laterally flattened shells.

They were smooth, with very little ornamentation, which led researchers to think of them resembling plant leaves and gave rise to their name, which means leaf-horn. They can be found in three regions that I know of.  In the Jurassic of Italy near western Sicily's Rosso Ammonitico Formation, Lower Kimmeridgian fossiliferous beds of Monte Inici East and Castello Inici (38.0° N, 12.9° E: 26.7° N, 15.4° E) and in the Arimine area, southeastern Toyama Prefecture, northern central Japan, roughly, 36.5° N, 137.5° E: 43.6° N, 140.6° E. And in Madagascar, in the example seen here found near Sokoja, Madagascar, off the southeast coast of Africa at 22.8° S, 44.4° E: 28.5° S, 18.2° E.

WEYLA OF THE SUNRISE FORMATION

Weyla (Nielsen, 1963) New York Canyon, Nevada

A lovely example of the large bivalve, Weyla (Nielsen, 1963), from the earliest known Jurassic Ferguson Hill Member (Hettangian and Sinemurian) of the Sunrise Formation in the New York Canyon area of west-central Nevada, USA.

The end-Triassic mass extinction was global, severe, and accompanied by worldwide disturbance to carbonate ramp and platform sedimentation. We see the effects played out in the Ferguson Hill Member of the Sunrise Formation. These outcrops are the result of the earliest known Jurassic carbonate ramp produced in the back-arc basin along NE Panthalassa following the extinction event to determine the biotic constituents and timing of local ecological recovery.

The Ferguson Hill Member (Hettangian and Sinemurian) of the Sunrise Formation in the New York Canyon area of west-central Nevada, USA has a lovely counterpart in the Rockies of British Columbia, Canada, explored over three field seasons in the early 2000s before being closed off as a provincial park.

In the Hettangian, post-extinction biosiliceous sedimentation extended to the inner ramp, where an ooid and grapestone shoal marked the outermost extent of a narrow belt of carbonate sedimentation. An early recovery phase in the late Hettangian is characterized by widespread, laterally homogeneous, demosponge-dominated level-bottom sedimentation across the mid- to inner-ramp, in addition to limited trophic tiering (sessile epifaunal suspension-feeding and mobile infaunal deposit-feeding), substantial ramp aggradation, and poor settling conditions for competitive benthic colonizers (e.g., corals, crinoids, infaunal bivalves).

Within 1.6–2 Myr after the extinction (in the early Sinemurian), a late recovery phase is recognized by the appearance of epifaunal grazers (gastropods, echinoids) and suspension feeders (crinoids, solitary scleractinian corals), phototrophic microbialites (oncoids, and possibly photosymbionts within corals), and infaunal deposit or suspension feeders (bivalves).

Although the late recovery faunas included more trophic levels than pre-extinction carbonate ramp habitats, development and progradation of the first Jurassic carbonate ramp still relied heavily on sponge, microbialite, and abiotic mineralization.

JURASSIC SUNRISE FORMATION OF NEVADA

The entrance to the Pliensbachian-Toarcian localities at Joker Peak and Mina Peak Members of the Sunrise Formation, Nevada, USA.

The Jurassic ammonites of this section were first studied by Dr. Paul Smith, past Chair of Earth and Ocean Sciences, University of British Columbia and more recently by Andrew Caruthers et al.

Caruthers and his team took a goodly look at the Early Jurassic coral fauna. It is nice to see the other marine invertebrates getting the attention they deserve. Caruthers is an interesting cat. He uses a combination of invertebrate palaeontology and isotope geochemistry to ponder the effects of paleoclimate change and mass extinction. He has turned his eye in recent years to the Paleozoic of the Michigan Basin AND he's based in Kalamazoo, MI. Yep, Kalamazoo.

Others have taken up the mantle of discovery from these sites. Pengfei Hou did his 2014 Masters thesis comparing the Sinemurian (Early Jurassic) stratigraphic sections of Last Creek, British Columbia and Five Card Draw, Nevada including a detailed taxonomic study from the Involutum Zone to the lower part of the Harbledownense Zone of the Sinemurian.

HOPLOSCAPHITES NEBRASCENSIS

This sweet macroconch with her lovely oil-in-water colouring is a Hoploscaphites nebrascensis (Owen, 1852). This is the female form of the ammonite that has a larger shell than the male, or microconch.

Hoploscaphites nebrascensis is an upper Maastrichtian species and index fossil. It marks the top of ammonite zonation for the Western Interior. This species has been recorded from Fox Hills Formation in North and South Dakota as well as the Pierre Shale in southeastern South Dakota and northeastern Nebraska.

It is unknown from Montana, Wyoming, and Colorado due to the deposition of coeval terrestrial units. It has possibly been recorded in glacial deposits in Saskatchewan and northern North Dakota, but that is hearsay. 

Outside the Western Interior, this species has been found in Maryland and possibly Texas in the Discoscaphites Conrad zone. This lovely one is in the collection of the deeply awesome (and enviable) José Juárez Ruiz. A big thank you to Joshua DrSlattmaster J Slattery for his insights on this species.

EUHOPLITES OF FOLKSTONE

Euhoplites Ammonite, Collection of José Juárez Ruiz

A beautiful Euhoplites ammonite from Folkstone, UK. Euhoplites is an extinct ammonoid cephalopod from the Lower Cretaceous, characterized by strongly ribbed, more or less evolute, compressed to inflated shells with flat or concave ribs, typically with a deep narrow groove running down the middle.

In some, ribs seem to zigzag between umbilical tubercles and parallel ventrolateral clavi. In others, the ribs curve forward from the umbilical shoulder and lap onto either side of the venter.

Its shell is covered in the lovely lumps and bumps we associate with the genus. The function of these adornments are unknown. I wonder if they gave them greater strength to go deeper into the ocean to hunt for food. 

They look to have been a source of hydrodynamic drag, likely preventing Euhoplites from swimming at speed. Studying them may give some insight into the lifestyle of this ancient marine predator. Euhoplites had shells ranging in size up to a 5-6cm. We find them in Lower Cretaceous, middle to upper Albian age strata. Euhoplites has been found in Middle and Upper Albian beds in France where it is associated respectively with Hoplites and Anahoplites, and Pleurohoplites, Puzosia, and Desmoceras; in the Middle Albian of Brazil with Anahoplites and Turrilites; and in the Cenomanian of Texas.

This species is the most common ammonite from the Folkstone Fossil Beds in southeastern England where a variety of species are found, including this 37mm beauty from the collections of José Juárez Ruiz.

HOLCOPHYLLOCERAS MEDITERRANEUM

There is delightful suturing on this lovely ammonite, Holcophylloceras mediterraneum, (Neumayr 1871) from Late Jurassic (Oxfordian) deposits near Sokoja, Madagasgar.

The shells had many chambers divided by walls called septa. The chambers were connected by a tube called a siphuncle which allowed for the control of buoyancy with the hollow inner chambers of the shell acting as air tanks to help them float.

We can see the edges of this specimen's shell where it would have continued out to the last chamber, the body chamber, where the ammonite lived. Picture a squid or octopus, now add a shell and a ton of water. That's him!

They were prolific breeders that evolved rapidly. If you could cast a fishing line into our ancient seas, it is likely that you would hook an ammonite, not a fish. They were prolific back in the day, living (and sometimes dying) in schools in oceans around the globe. We find ammonite fossils (and plenty of them) in sedimentary rock from all over the world.

In some cases, we find rock beds where we can see evidence of a new species that evolved, lived and died out in such a short time span that we can walk through time, following the course of evolution using ammonites as a window into the past.

For this reason, they make excellent index fossils. An index fossil is a species that allows us to link a particular rock formation, layered in time with a particular species or genus found there. Generally, deeper is older, so we use the sedimentary layers rock to match up to specific geologic time periods, rather the way we use tree-rings to date trees. A handy way to compare fossils and date strata across the globe.

OH KEUPPIA: ANCIENT OCTOPUS FROM LEBANON

An adorable example of Keuppia levante (Fuchs, Bracchi & Weis, 2009), an extinct genus of octopus that swam our ancient seas back in the Cretaceous. The dark black and brown area you see is his ink sac which has been preserved for a remarkable 95 million years.

This cutie is in the family Palaeoctopodidae, and one of the earliest representatives of the order Octopoda. These ancient marine beauties are in the class Cephalopoda making them relatives of our modern octopus, squid and cuttlefish.

There are two species of Keuppia, Keuppia hyperbolaris and Keuppia levante, both of which we find as fossils. We find their remains, along with those of the genus Styletoctopus, in Cretaceous-age Hâqel and Hjoula localities in Lebanon. For many years, Palaeoctopus newboldi (Woodward, 1896) from the Santonian limestones at Sâhel Aalma, Lebanon, was the only known pre‐Cenozoic coleoid cephalopod believed to have an unambiguous stem‐lineage representative of Octobrachia fioroni. 

With the unearthing of some extraordinary specimens with exquisite soft‐part preservation in the Lebanon limestones, our understanding of ancient octopus morphology has blossomed. The specimens are from the sub‐lithographical limestones of Hâqel and Hâdjoula, in north‐west Lebanon. These localities are about 15 km apart, 45 km away from Beirut and 15 km away from the coastal city of Jbail. Fuchs et al. put a nice little map in their 2009 paper that I've included and referenced here.

Palaeoctopus newboldi had a spherical mantle sac, a head‐mantle fusion, eight equal arms armed with suckers, an ink sac, a medially isolated shell vestige, and a pair of (sub‐) terminal fins. The bipartite shell vestige suggests that Palaeoctopus belongs to the octopod stem‐lineage, as the sister taxon of the Octopoda, the Cirroctopoda, is characterized by an unpaired clasp‐like shell vestige (Engeser 1988; Haas 2002; Bizikov 2004).

It is from the comparisons of Canadian fauna combined with those from Lebanon and Japan that things really started to get interesting with fossil Octobrachia. Working with fossil specimens from the Campanian of Canada, Fuchs et al. (2007a ) published on the first record of an unpaired, saddle‐shaped shell vestige that might have belonged to a cirroctopod. 

Again from the Santonian–Campanian of Canada and Japan, Tanabe et al. (2008) reported on at least four different jaw morphotypes. Two of them (Paleocirroteuthis haggarti  Tanabe et al. , 2008 and Paleocirroteuthis pacifica  Tanabe et al ., 2008) have been interpreted as being of cirroctopod type, one of octopod type, and one of uncertain octobrachiate type. 

Interestingly Fuchs et al. have gone on to describe the second species of Palaeoctopus, the Turonian Palaeoctopus pelagicus from limestones at Vallecillo, Mexico. While more of this fauna will likely be recovered in time, their work is based solely on a medially isolated shell vestige.

Five new specimens have been found in the well-known Upper Cenomanian limestones at Hâqel and Hâdjoula in Lebanon that can be reliably placed within the Octopoda. Fuchs et al. described these exceptionally well‐preserved specimens and to discuss their morphology in the context of phylogeny and evolution in their 2008 paper (2009 publishing) in the Palaeontology Association Journal, Volume 51, Issue 1.

The presence of a gladius vestige in this genus shows a transition from squid to octopus in which the inner shell has divided in two in early forms to eventually be reduced to lateralized stylets, as can be seen in Styletoctopus.

The adorable fellow you see here with his remarkable soft-bodied preservation and inks sack and beak clearly visible is Keuppia levante. He hails from Late Cretaceous (Upper Cenomanian) limestone deposits near Hâdjoula, northwestern Lebanon. The vampyropod coleoid, Glyphiteuthis abisaadiorum n. sp., is also found at this locality. This specimen is about 5 cm long.

Fuchs, D.; Bracchi, G.; Weis, R. (2009). "New octopods (Cephalopoda: Coleoidea) from the Late Cretaceous (Upper Cenomanian) of Hâkel and Hâdjoula, Lebanon". Palaeontology. 52: 65–81. doi:10.1111/j.1475-4983.2008.00828.x.

Photo one: Fossil Huntress. Figure Two: Topographic map of north‐western Lebanon with the outcrop area in the upper right-hand corner. Fuchs et al, 2009.  

TITANITES: FERNIE AMMONITE SITE

The Fernie ammonite, Titanites occidentalis, from outcrops on Coal Mountain near Fernie, British Columbia, Canada. 

This beauty is the remains of a carnivorous cephalopod within the family Dorsoplanitidae that lived and died in a shallow sea some 150 million years ago.

If you would like to get off the beaten track and hike up to see this ancient beauty, you will want to head to the town of Fernie in British Columbia close to the Alberta border. 

Driving to the trail base is along an easy access road just east of town along Fernie Coal Road. There are some nice exposures of Cretaceous plant material on the north side (left-hand side) of the road as you head from Fernie towards Coal Creek. I recently drove up to Fernie to look at Cretaceous plant material and locate the access point to the now infamous Late Jurassic (Tithonian) Titanites (S.S. Buckman 1921) site. While the drive out of town is on an easy, well-maintained road, the slog up to the ammonite site is a steep 3-hour push.

The first Titanites occidentalis was about one-third the size and was incorrectly identified as Lytoceras, a fast-moving nektonic carnivore. The specimen you see here is significantly larger at 1.4 metres (about four and a half feet) and rare in North America. 

Titanites occidentalis, the Western Giant, is the second known specimen of this extinct fossil species. The first was discovered in 1947 in nearby Coal Creek by a British Columbia Geophysical Society mapping team.

In the summer of 1947, a field crew was mapping coal outcrops for the BC Geological Survey east of Fernie. One of the students reported finding “a fossil truck tire.” Fair enough. The similarity of size and optics are pretty close to your average Goodridge. 

A few years later, GSC Paleontologist Hans Frebold described and named the fossil Titanites occidentalis after the large Jurassic ammonites from Dorset, England. The name comes from Greek mythology. Tithonus, as you may recall, was the Prince of Troy. He fell in love with Eos, the Greek Goddess of the Dawn. Eos begged Zeus to make her mortal lover immortal. Zeus granted her wish but did not grant Tithonus eternal youth. He did indeed live forever — aging hideously. Ah, Zeus, you old trickster. It is a clever play on time placement. Dawn being the beginning of the day and the Tithonian being the latest age of the Late Jurassic. Clever Hans!

Hiking to the Fernie Ammonite

From the town of Fernie, British Columbia, head east along Coal Creek Road towards Coal Creek. The site is 3.81 km from the base of the Coal Creek Road to the trailhead as the crow flies. I've mapped it here for you in yellow and added the wee purple GPS marker for the ammonite site. There is a nice, dark grey to black roadcut exposure of Cretaceous plants on the north side of the dirt road that is your cue to pull over and park.  

You access the trailhead on the south side of the road. You'll need to cross the creek to begin your ascent. There is no easy way across the creek and you'll want to tackle this one with a friend when the water level is low. The beginning of the trail is not clear but a bit of searching will reveal the trailhead with its telltale signs of previous hikers. This is a 2-3 hour moderate 6.3-kilometre hike up & back bush-whacking through scrub and fallen trees. Heading up, you'll make about a 246-metre elevation gain. You won't have a cellular signal up here but if you download the Google Map to your mobile, you'll have GPS to guide you. 

If you're coming in from out of town, the closest airport is Cranbrook. Then it is about an hour and change to Fernie and another 15-minutes or so to the site.

You'll want to leave your hammers with your vehicle (no need to carry the weight) as this site is best enjoyed with a camera. If you'd like to see the ammonite but are not keen on the hike, a cast has been made by fossil preparator Rod Bartlett and is on display at the Courtenay Museum in Courtenay, Vancouver Island, Canada. 

Fernie Ammonite Palaeo Coordinates: 49°29'04"N 115°00'49"W

GREEN SEA TURTLE

The Green Sea Turtle, Chelonia mydas, also known as the Green Turtle, Black Sea Turtle or Pacific Green Turtle is a species in the family Cheloniidae.

It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans, but it is also found in the Indian Ocean. The common name refers to the usually green fat found beneath its carapace, not to the colour of its carapace, which is olive to black.

This sea turtle's dorsoventrally flattened body is covered by a large, teardrop-shaped carapace; it has a pair of large, paddle-like flippers. It is usually lightly coloured, although in the eastern Pacific populations' parts of the carapace can be almost black. Unlike other members of its family, such as the hawksbill sea turtle, C. mydas is mostly herbivorous. The adults usually inhabit shallow lagoons, feeding mostly on various species of seagrasses. The turtles bite off the tips of the blades of seagrass, which keeps the grass healthy.

Like other sea turtles, green sea turtles migrate long distances between feeding grounds and hatching beaches. Many islands worldwide are known as Turtle Island due to green sea turtles nesting on their beaches. Females crawl out on beaches, dig nests and lay eggs during the night. Later, hatchlings emerge and scramble into the water. Those that reach maturity may live to 80 years in the wild.

Researchers at the Senckenberg Research Institute in Frankfurt, Germany discovered the remains of the oldest fossilized sea turtle known to date. Remains from a new species, Desmatochelys padillai sp, including fossilized shell and bones have been found at two outcrops near Villa de Leyva, Colombia. The find was published in the journal PaleoBios, dates the reptile at 120 million years old – 25 million years older than any previously known specimen of this beautiful and long-lived turtle.

ANDROGYNOCERAS LATAECOSTA

This gorgeous Lower Pliensbachian macroconch of the ammonite Androgynoceras lataecosta was found as a nodule from the Green Ammonite beds, Lower Pliensbachian, Stonebarrow Marl Member, Charmouth Mudstone Formation (190 MYA) at Charmouth Beach, Dorset Coast. 

This specimen was found, prepped and photographed by the lovely and talented Lizzie Hingley of Stonebarrow Fossils. 

And what a delightful surprise! It is quite a small nodule to contain a macroconch of this species. Generally, these smaller concretions contain the diminutive male microconchs of Androgynoceras (Hyatt, 1867) if you are lucky — sometimes a Tragophylloceras loscombi (Sowerby, 1814) — or nothing at all if you are not. 

We see a great variation in this species and the ammonite species that make up this population. Murray Edmunds from Chipping Norton, UK shared some of his insights on why we see such variation and how a phylogenetic species concept may be masking a continuum that tells a very different story.  

We are starting to recognise that these could all be variants of one interbreeding population — with a highly variable duration of a juvenile Capricorn stage. Palaeontologists use a phylogenetic species concept as you cannot test reproductive isolation in any but the most recent of fossils.

By definition, individuals within an interbreeding population cannot belong to different species, let alone different genera. In palaeontology we can only interpret what we see with reference to what we understand of biology. 

In the Davoei Zone Liparoceratidae we have a single lineage that evolves into Oistoceras. The microconchs (putative males) are small Capricorns, and the macroconchs (putative females) are very variable: they have a Capricorn juvenile stage that can be expressed for only a few mm (or not at all), or for many cm. But eventually, the adult macroconch body chamber acquires liparoceratid ornament — inflated and bipinnate with numerous secondary ribs. 

Unfortunately, the green ammonite beds at Charmouth preserve only juvenile macroconchs so we don’t get to appreciate the similarity of the mature adult shell form. We see them at a size where individuals can look very different from each other. 

Historically, this difference in appearance led to all the individuals — both micro and macroconchs — with prolonged Capricorn morphology being assigned to Androgynoceras and those macroconchs lacking the juvenile Capricorn stage (as is typical in their Ibex zone ancestors) to be called Liparoceras. 

Different species were named for different variants. But this is a purely morphological approach to nomenclature and does not reflect the taxonomy used for extant organisms where we try to reflect phylogeny.

But as more and more examples are collected, we start to see that these specimens form a continuum. And as we follow them up through time, we see that all of them (microconchs and macroconchs, regardless of the extent of the Capricorn stage — although that tends to become more prolonged through time — simultaneously evolve progressively forwardly projected ribs across the venter, culminating in Oistoceras. 

This simultaneous evolutionary change across the entire Liparoceratid population more or less proves that we have a single interbreeding clade. And that it is separate from Becheiceras – through that’s another story! And they all go extinct simultaneously too, whereas Becheiceras carries on into the Margaritatus Zone. If you're a grad student looking to do your thesis, there is a very interesting story you could tell!

If you fancy a web stroll through some beautifully prepped specimens from Jurassic Coast, UK, or if you'd like to get some prepped, you can check out Lizzie's superb skill here: https://www.stonebarrowfossils.co.uk/  / Photos: Lizzie Hingley, Stonebarrow Fossils

AMMONITES: CHAMBERED BEAUTY

Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids — octopus, squid, and cuttlefish — than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species vanished in the Cretaceous–Paleogene extinction event. 

The chambered part of the ammonite shell is called a phragmocone. It contains a series of progressively larger chambers, called camerae — the singular is camera — that are divided by thin walls called septa —the singular is septum. You can see the interior of an ammonite with the discreet chambers in this lovely sliced Cleoniceras sp. from Madagascar.

Only the last and largest chamber, the body chamber, was occupied by the living animal at any given moment. As it grew, it added newer and larger chambers to the open end of the coil. Where the outer whorl of an ammonite shell largely covers the preceding whorls, the specimen is said to be involute. Anahoplites is a good example of this. Where it does not cover those preceding, the specimen is said to be evolute, something we see in the ammonite Dactylioceras.

A thin living tube called a siphuncle passed through the septa, extending from the ammonite's body into the empty shell chambers. Through a hyperosmotic active transport process, the ammonite emptied the water out of these shell chambers. This enabled it to control the buoyancy of the shell and thereby rise or descend in the water column.

A primary difference between ammonites and nautiloids is the siphuncle of ammonites — excepting Clymeniina — which runs along the ventral periphery of the septa and camerae — the inner surface of the outer axis of the shell — while the siphuncle of nautiloids runs more or less through the centre of the septa and camerae.

Clymenia has a closely coiled evolute shell that may be faintly ribbed. The dorsum, on the inside of the whorl, is slightly impressed, a result of the outermost whorl slightly enveloping the previous. The venter may be rounded or acute. The suture is simple, with a broad ventral saddle, broad lateral lobe, a dorsolateral saddle, and a moderately deep hidden dorsal lobe. Septal necks are usually short and do not form a continuous tube. The suture and siphuncle are characteristic of the family found in Europe and Western Australia.

If you fancy a read, check out the Treatise on Invertebrate Paleontology, Part L Ammonoidea; Geological Society of America and Univ of Kansas Press, 1964.

CERATITES NODOSUS

A lovely beast of an ammonite, Cératites nodosus, from the collections of the deeply awesome Ange Mirabet. This species is an extinct genus of nektonic marine carnivore from limestone deposits near Alsace on the Rhine River plain of northeastern France.

You can see the nice ceratitic suture pattern on this specimen with his smooth lobes and frilly saddles. The sutures would have increased the strength of the shell and allowed Ceratites (de Haan, 1825) to dive deeper, bearing the additional pressure of the sea in search of food.

Ammonite shells are made up predominantly of calcium carbonate in the form of aragonite and proteinaceous organic matrix or conchiolin arranged in layers: a thin outer prismatic layer, a nacreous layer and an inner lining of prismatic habitat. While their outer shells are generally aragonite, aptychus — those hard shelly plates you see — are distinct as they are composed of calcite.

These ammonites lived in open shallow, to subtidal and basinal environments some 247 to 221 million years ago. We've found them, thus far, in just over forty collections from nearly ninety fossil deposits around the globe. Fossils of species have been found in the Triassic of Austria, Canada, China, France, Germany, Hungary, India, Israel, Italy, Pakistan, Poland, Russia, Thailand, Turkey and the United States.

The parent taxon is Ceratitinae according to E. T. Tozer 1981. That's our own Tim Tozer, one of the great knights-errant of the Triassic timescale. Born a Brit but spent his life exploring the wilds of Canada and the Arctic Archipelago. It was Tim Tozer and Norm Silberling who published the classic milestones of the Triassic timescale, "Biostratigraphic Classification of the Marine Triassic in North America, Geological Society of America, Special Paper 110." The Global Triassic: Bulletin 41 from the New Mexico Museum of Natural History and Science by Lucas and Spielmann honours them in their work. Collection of Ange Mirabet, Strasbourg, France.

OH, CORONICERAS!

This Jurassic ammonite is from an all but inaccessible site in Sayward, Bonanza Group, Vancouver Island. He's a Coroniceras with a truly marvellous keel.

By the time these ammonites were being buried in sediment, Wrangellia, the predominately volcanic terrane that now forms Vancouver Island and the Queen Charlotte Islands, had made its way to the northern mid-latitudes.

Within the basal part of the sequence, sedimentary beds are found interbedded with lapilli and crystal-tuffs. Here you'll see maroon tuffaceous sandstone, orange-grey sandstone, granule sandstone and conglomerate. Within them we find ammonites nestled in with gastropods and pelecypods. 

While the fossiliferous outcrop is quite small, the Bonanza group is much larger, estimated to be at least 1000 metres thick. The site is quite small and in an active logging area, so the window to collect was limited. The drive up the mountain was thrilling as there had just been heavy rains and the road was washed out and narrowed until it was barely the width of our wheelbase and then narrowed further to be just shy of the width of the vehicle — thrilling, to say the least. So scary that my passengers all got out as there was a high probability of going head-first over the edge. I navigating by some handwritten field notes and a wee map on a paper napkin that should have read, "park at the bottom and hike up." Nope. We didn't park at the bottom and were halfway up the mountain before the road narrowed out. Too narrow to turn around, so the only way was up. 

Coroniceras with a sweet, sweet keel

Graham Beard from Qualicum Beach was the fellow who showed me the site and drew the wee map for me. I cannot recall everyone on the trip, but Perry Poon was there — he shot a video of the drive up that he described as thrilling. I've never seen it but would like to one day — and so was Patricia Coutts with her lovely Doberman. 

She and I had just done a trip up to Goldbridge where the cliff we were on had turned into a landslide into a ravine so she was feeling understandably cautious about the power of Mother Nature. Picture the angle, the hood of my jeep riding high and hiding what remained of the road beneath and a lovely stick shift that made you roll backwards a wee bit with every move to put it into gear. So, without being able to see the very narrow path beneath, I had to just keep going. Both Perry and Patricia helped with filling in the potholes so my tires would have something to grip. I bent the frame on the jeep heading up and had some explaining to do when I returned it to the car rental place. 

In the end, we found what we were looking for. Memekay yields a mix of ammonites, gastropods and bivalves. Many of them poorly preserved. It was a hell of a ride but well worth the effort as we found some great fossils and with them more information on the palaeontology and geology of Vancouver Island. Just look at the keel on this beauty.

HETEROMORPH AMMONITES

Heteromorph Ammonites, Sowerby 1837

Ammonite shells have been collected by people for millennia. These ammonites are known from the Late Triassic and the middle Jurassic but were most abundant and creative in their form in the Cretaceous (Wiedmann, 1969).

The beautiful plate you see here showing two ammonites is from Sowerby (1837) and is one of the very first scientifically accurate studies of heteromorph ammonites. We see similar species to the heteromorphs above in the Nanaimo Group of Vancouver Island, British Columbia.

During medieval times they were believed to be snakes that had been turned into stone and were sold to people going on pilgrimages. They have been found in archaeological sites in many parts of the world. We find them in archaeological remains spanning human history, across cultures and civilizations.

Pictet's Paleontology Second Edition, 1853-57

Ammonites are prized for their scientific and aesthetic value and have been used as building materials, jewelry, amulets, charms to aid in the hunt, religious totems amongst other things. The original discus used by the ancient Greeks in their Olympics was a fossilized ammonite.

The beautiful plate to the left shows some of the heteromorph ammonites from Pictet's Paleontology in its second edition (1853-57). Some of the figures are copied from Astier or d'Orbigny works, not included in the first edition.

Ammonites are pleasing to the eye, usually taking on a planispiral form— although there are some helically spiralled and fully crazy spiralled forms — known as heteromorphs.

The most interesting of all the heteromorphs are the Cretaceous heteromorph ammonites of the suborder Ancyloceratina. The juveniles of this suborder played with every possible variation in their shell shape from regular planispiral and orthoconic to torticonic, hamitoconic and gyroconic.

The adults uncoiled the last whorl of their shell forming the characteristic U-shaped recurved body chamber you see below. A curious form as the aperture faces upward. Ammonites of the suborder Ancyloceratina may have developed a stationary brooding phase that could have several ecological advantages over free-swimming monomorphic ammonites.

Ancyloceras matheronianus

Alexander Arkipkin wrote a great paper on them in the Journal of Molluscan Studies back in 2014 — "Getting hooked: the role of a U-shaped body chamber in the shell of adult heteromorph ammonites."

His focus is on the morphological features of the adult shell in heteromorph ammonites of the suborder Ancyloceratina but does useful comparisons to a vast number of heteromorph ammonites in collections at the Department of Earth Sciences of the Natural History Museum, London.

Heteromorphs come in a variety of shapes and sizes. They must have intrigued and mystified those who were first to find them as they do not have an intuitive shape at all for a marine predator. Do give Arkipkin's paper a read and bask in the wonder of the amazing forms of these ancient cephalopods.

Reference: Getting hooked: the role of a U-shaped body chamber in the shell of adult heteromorph ammonites. Journal of Molluscan Studies, Volume 80, Issue 4, November 2014, Pages 354–364, https://doi.org/10.1093/mollus/eyu019 https://academic.oup.com/mollus/article/80/4/354/1021718

Image 3-5: Ancyloceras matheronianus. A. General view. B. Inner part of vertical shaft with resolved ribs (RR). C. Inner part of U-shaped adult living chamber with less resolved ribs (WR). Abbreviations as in Figure 2. Scale bar = 1 cm.

ETHELDRED BENETT: SPONGE HUNTRESS

Hoplites (Hoplites) bennettiana (Sowerby, 1826)

A beautiful example of the ammonite, Hoplites (Hoplites) bennettiana (Sowerby, 1826), from Early Albian localities in the Carrière de Courcelles Villemoyenne, Région de Troyes, near Champagne in northeastern France.

The species name is an homage to Etheldred Benett, an early English geologist often credited with being the first female geologist — a fossil collector par excellence.

She was also credited with being a man  —  the Natural History Society of Moscow awarding her membership as Master Etheldredus Benett in 1836. The confusion over her name (it did sound masculine) came again with the bestowing of a Doctorate of Civil Law from Tsar Nicholas I.

The Tsar had read Sowerby's Mineral Conchology, a major fossil reference work which contained the second-highest number of contributed fossils of the day, many the best quality available at the time. Forty-one of those specimens were credited to Benett. Between her name and this wonderous contribution to a growing science, the Russian Tsar awarded the Doctorate to what he believed was a young male scientist on the rise. He believed in education, founding Kiev University in 1834, just not for women. He was an autocratic military man frozen in time — the thought that this work could have been done by a female unthinkable. Doubly charming is that the honour from the University of St Petersburg was granted at a time when women were not allowed to attend St. Pete's or any higher institutions. That privilege arrived in 1878, twenty years after Nicholas I's death.

Benett took these honours (and social blunders) with grace. She devoted her life to collecting and studying fossils from the southwest of England, amassing an impressive personal collection she openly shared with geologist friends, colleagues and visitors to her home. Her specialty was fossils from the Middle Cretaceous, Upper Greensand in the Vale of Wardour — a valley in the county of Wiltshire near the River Nadder.

Etheldred was a local Wiltshire girl. Born Etheldred Benett on 22 July 1775 at Pyt House, Tisbury, Wiltshire, the eldest daughter of the local squire Thomas Benett. Etheldred's interest was cultivated by the botanist Aylmer Bourke Lambert (1761-1842), a founding member of the Linnean Society. Benett's brother had married Lucy Lambert, Aylmer's half-sister. Aylmer was a Fellow of the Royal Society and the Society of the Arts. He was also an avid fossil collector and member of the Geological Society of London. The two met and got on famously.

Aylmer kindled an interest in natural history in both of Benett's daughters. Etheldred had a great fondness in geology, stratigraphy and all things paleo, whilst her sister concentrated on botany. Etheldred had a distinct advantage over her near contemporary, the working-class Mary Anning (1799-1847), in that Benett was a woman of independent wealth who never married — and didn't need to — who could pursue the acquisition and study of fossils for her own interest.

While Anning was the marine reptile darling of the age, she was also greatly hindered by her finances. "She sells, seashells by the seashore..." while chanted in a playful spirit today, was not meant kindly at the time. Aylmer's encouragement emboldened Etheldred to go into the field to collect for herself — and collect she did. Profusely.

Benett’s contribution to the early history of Wiltshire geology is significant. She corresponded extensively with the coterie of gentlemen scientists of the day —  Gideon Mantell, William Buckland, James Sowerby, George Bellas Greenough and, Samuel Woodward. She also consorted with the lay folk and had an ongoing correspondence with William Smith, whose stratigraphy work had made a favourable impression on her brother-in-law, Aylmer.

Her collections and collaboration with geologists of the day were instrumental in helping to form the field of geology as a science. One colleague and friend, Gideon Mantell, British physician, geologist and paleontologist, who discovered four of the five genera of dinosaurs and Iguanadon, was so inspired by Benett's work he named this Cretaceous ammonite after her — Hoplites bennettiana.

Benett's fossil assemblage was a valuable resource for her contemporaries and remains so today. It contains thousands of Jurassic and Cretaceous fossil specimens from the Wiltshire area and the Dorset Coast, including a myriad of first recorded finds. The scientific name of every taxon is usually based on one particular specimen, or in some cases multiple specimens. Many of the specimens she collected serve as the Type Specimen for new species.

Fossil Sponge, Polypothecia quadriloba, Warminster, Wiltshire

Her particular interest was the collection and study of fossil sponges. Alcyonia caught her eye early on. She collected and recorded her findings with the hope that one of her colleagues might share her enthusiasm and publish her work as a contribution to their own.

Alas, no one took up the helm — those interested were busy with other pursuits (or passed away) and others were less than enthusiastic or never seemed to get around to it.

To ensure the knowledge was shared in a timely fashion, she finally wrote them up and published them herself. You can read her findings in her publication, ‘A Catalogue of Organic Remains of the County of Wiltshire’ (1831), where she shares observations on the fossil sponge specimens and other invert goodies from the outcrops west of town.

She shared her ideas freely and donated many specimens to local museums. It was through her exchange of observations, new ideas and open sharing of fossils with Gideon Mantell and others that a clearer understanding of the Lower Cretaceous sedimentary rocks of Southern England was gained.

In many ways, Mantell was drawn to Benett as his ideas went against the majority opinion. At a time when marine reptiles were dominating scientific discoveries and discussions, he pushed the view that dinosaurs were terrestrial, not amphibious, and sometimes bipedal. Mantell's life's work established the now-familiar idea that the Age of Reptiles preceded the Age of Mammals. Mantell kept a journal from 1819-1852, that remained unpublished until 1940 when E. Cecil Curwen published an abridged version. (Oxford University Press 1940). John A. Cooper, Royal Pavilion and Museums, Brighton and Hove, published the work in its entirety in 2010.

I was elated to get a copy, both to untangle the history of the time and to better learn about the relationship between Mantell and Benett. So much of our geologic past has been revealed since Mantell's first entry two hundred years ago. The first encounter we share with the two of them is a short note from March 8, 1819. "This morning I received a letter from Miss Bennett of Norton House near Warminster Wilts, informing me of her having sent a packet of fossils for me, to the Waggon Office..." The diary records his life, but also the social interactions of the day and the small connected community of the scientific social elite. It is a delight!

Though a woman in a newly evolving field, her work, dedication and ideas were recognized and appreciated by her colleagues. Gideon Mantell described her as, "a lady of great talent and indefatigable research," whilst the Sowerbys noted her, "labours in the pursuit of geological information have been as useful as they have been incessant."

Benett produced the first measured sections of the Upper Chicksgrove quarry near Tisbury in 1819, published and shared with local colleagues as, "the measure of different beds of stone in Chicksgrove Quarry in the Parish of Tisbury.” The stratigraphic section was later published by naturalist James Sowerby without her knowledge. Her research contradicted many of Sowerby’s conclusions.

She wrote and privately published a monograph in 1831, containing many of her drawings and sketches of molluscs and sponges. Her work included sketches of fossil Alcyonia (1816) from the Green Sand Formation at Warminster Common and the immediate vicinity of Warminster in Wiltshire.

Echinoids and Bivalves. Collection of Etheldred Benett (1775-1845)

The Society holds two copies, one was given to George Bellas Greenough, and another copy was given to her friend Gideon Mantell. This work established her as a true, pioneering biostratigrapher following but not always agreeing with the work of William Smith.

If you'd like to read a lovely tale on William's work, check out the Map that Changed the World: William Smith and the Birth of Modern Geology by Simon Winchester. It narrates the intellectual context of the time, the development of Smith's ideas and how they contributed to the theory of evolution and more generally to a dawning realization of the true age of the earth.

The book describes the social, economic or industrial context for Smith's insights and work, such as the importance of coal mining and the transport of coal by means of canals, both of which were a stimulus to the study of geology and the means whereby Smith supported his research. Benett debated many of the ideas Smith put forward. She was luckier than Smith financially, coming from a wealthy family, a financial perk that allowed her the freedom to add fossils to her curiosity cabinet at will.

Most of her impressive collection was assumed lost in the early 20th century. It was later found and purchased by an American, Thomas Bellerby Wilson, who donated it to the Academy of Natural Sciences of Philadelphia. Small parts of it made their way into British museums, including the Leeds City Museum, London, Bristol and to the University of St. Petersburg. These collections contain many type specimens and some of the very first fossils found — some with the soft tissues preserved. When Benett died in 1845, it was Mantell who penned her obituary for the London Geological Journal.

In 1989, almost a hundred and fifty years after her death, a review of her collection had Arthur Bogen and Hugh Torrens remark that her work has significantly impacted our modern understanding of Porifera, Coelenterata, Echinodermata, and the molluscan classes, Cephalopoda, Gastropoda, and Bivalvia. A worthy legacy, indeed.

Her renown lives on through her collections, her collaborations and through the beautiful 110 million-year-old ammonite you see here, Hoplites bennettiana. The lovely example you see here is in the collection of the deeply awesome Christophe Marot.

Spamer, Earle E.; Bogan, Arthur E.; Torrens, Hugh S. (1989). "Recovery of the Etheldred Benett Collection of fossils mostly from Jurassic-Cretaceous strata of Wiltshire, England, analysis of the taxonomic nomenclature of Benett (1831), and notes and figures of type specimens contained in the collection". Proceedings of the Academy of Natural Sciences of Philadelphia. 141. pp. 115–180. JSTOR 4064955.

Torrens, H. S.; Benamy, Elana; Daeschler, E.; Spamer, E.; Bogan, A. (2000). "Etheldred Benett of Wiltshire, England, the First Lady Geologist: Her Fossil Collection in the Academy of Natural Sciences of Philadelphia, and the Rediscovery of "Lost" Specimens of Jurassic Trigoniidae (Mollusca: Bivalvia) with Their Soft Anatomy Preserved.". Proceedings of the Academy of Natural Sciences of Philadelphia. 150. pp. 59–123. JSTOR 4064955.

Photo credit: Fossils from Wiltshire.  In the foreground are three examples of the echinoid, Cidaris crenularis, from Calne, a town in Wiltshire, southwestern England, with bivalves behind. Caroline Lam, Archivist at the Geological Society, London, UK. http://britgeodata.blogspot.com/2016/03/etheldred-benett-first-female-geologist_30.html

Photo credit: Fossil sponges Polypothecia quadriloba, from Warminster, Wiltshire. The genus labels are Benett’s, as is the handwriting indicating the species. The small number, 20812, is the Society’s original accession label from which we can tell that the specimen was received in April 1824. The tablet onto which the fossils were glued is from the Society’s old Museum.

PACHYDISCUS SUCHIAENSIS

Pachydiscus suchiaensis

The late Cretaceous ammonite Pachydiscus suchiaensis found in concretion amongst the 72 million-year-old grey shales of the Northumberland Formation, Campanian to the lower Maastrichtian, part of the upper Cretaceous, from Collishaw Point (Boulder Point to the locals), northwest side of Hornby Island, southwestern British Columbia.

Hornby is a glorious place to collect. The island is beautiful in its own right and the fossils from here often keep some of their original shell or nacre which makes them quite fetching.

This fellow is found amongst gastropods, shark teeth, fossil crabs, baculites and other bivalve fossils.

Like most of the fossils found at this locality, the specimen was found in concretions rolled smooth by time and tide. The concretions you find on the beach are generally round or oval in shape and are made up of hard, compacted sedimentary rock. If you are lucky, when you split them you see a fossil hidden within. The main topographic feature on Hornby Island is an arcuate mountain consisting of the resistant cliff-forming Geoffrey formation.

Near Shingle Spit about half a mile from the coast is Mount. Geoffrey 920-foot peak; from there the mountain gradually drops in elevation to the southeast and to the north.  It consists of a structurally simple 700-foot conglomerate homocline striking N 20° W and dipping to the northeast at a shallow angle of about 6°. The apex of the arcuate mountain belt points to the southwest.

Behind the mountain and almost enclosed by it is the fertile, green Strachan Valley. On the large peninsula which extends in a southeast direction from the north of the island towards St. John’s Point, the Hornby Formation outcrops forming the cliffs on the east side of Tribune Bay. The highest of these is about 200 feet. The argillaceous Lambert and Spray formations form the subdued lowlands of the island.

The coast of Hornby is probably a rising shoreline, as indicated by the almost perpendicular cliffs along its periphery. A hundred (100) foot cliffs of Lambert shale extends from Shingle Spit to Phipps Point, while from the latter to Boulder Point, the cliffs are not as steep and are covered in many places by vegetation.

PLESIOSAURS OF THE YORKSHIRE COAST

These two lovely Plesiosaur vertebrae were found by Liam Langley on fossil field trips to the Yorkshire Coast on the east coast of England.

Plesiosaurus was a large, carnivorous air-breathing marine reptile with strong jaws and sharp teeth that moved through the water with four flippers. We'd originally thought that this might not be the most aerodynamic design but it was clearly effective as they used the extra set to create a wee vortex that aided in their propulsion. In terms of mechanical design, they have a little something in common with dragonflies.

We've recreated plesiosaur movements and discovered that they were able to optimize propulsion to make use of their own wake. As their front flippers paddled in big circular movements, the propelled water created little whirlpools under their bellies.

The back flippers would then paddle between these whirlpools pushing the plesiosaur forward to maximal effect. They were very successful hunters, outcompeting ichthyosaurs who thrived in the Triassic but were replaced in the Jurassic and Cretaceous by these new aquatic beasties. Our ancient seas teemed with these predatory marine reptiles with their long necks and barrel-shaped bodies. Plesiosaurs were smaller than their pliosaur cousins, weighing in at about 450 kg or 1,000 lbs and reaching about 4.5 metres or 15 feet in length. For a modern comparison, they were roughly twice as long as a standard horse or about as long as a good size hippo.

Plesiosaurs first appeared in the latest Triassic, during the Rhaetian. They thrived in the Jurassic and vanished at the end of the Cretaceous in time with the K-Pg extinction event along with a host of other species. They are one of the marine reptiles that we associate with the infamous Mary Anning, a paleo darling of the early 19th century who found her first fossil specimen in the winter of 1823. These two vertebrae grace the home of the talented Mr. Langley. Anning's plesiosaur can be viewed in London's Natural History Museum.

ANEMONEFISH NURSERY

Anemonefish colonies usually consist of the reproductive male and female and a few male juveniles, which help tend the colony.

Although multiple males cohabit an environment with a single female, polygamy does not occur and only the adult pair exhibits reproductive behaviour. If the female dies, the social hierarchy shifts with the breeding male exhibiting protandrous sex reversal to become the breeding female.

The largest juvenile then becomes the new breeding male after a period of rapid growth. The existence of protandry in anemonefish may rest on the case that nonbreeders modulate their phenotype in a way that causes breeders to tolerate them. This strategy prevents conflict by reducing competition between males for one female. For example, by purposefully modifying their growth rate to remain small and submissive, the juveniles in a colony present no threat to the fitness of the adult male, thereby protecting themselves from being evicted by the dominant fish.

The reproductive cycle of anemonefish is often correlated with the lunar cycle. Rates of spawning for anemonefish peak around the first and third quarters of the moon. The timing of this spawn means that the eggs hatch around the full moon or new moon periods. One explanation for this lunar clock is that spring tides produce the highest tides during full or new moons. Nocturnal hatching during high tide may reduce predation by allowing for a greater capacity for escape. Namely, the stronger currents and greater water volume during high tide protect the hatchlings by effectively sweeping them to safety. Before spawning, anemonefish exhibit increased rates of anemone and substrate biting, which help prepare and clean the nest for the spawn.

In terms of parental care, male anemonefish are often the caretakers of eggs. Before making the clutch, the parents often clear an oval-shaped clutch varying in diameter for the spawn. Fecundity, or reproductive rate, of the females, usually ranges from 600 to 1500 eggs depending on her size. In contrast to most animal species, the female-only occasionally takes responsibility for the eggs, with males expending most of the time and effort. Male anemonefish care for their eggs by fanning and guarding them for 6 to 10 days until they hatch. In general, eggs develop more rapidly in a clutch when males fan properly, and fanning represents a crucial mechanism of successfully developing eggs.

This suggests that males can control the success of hatching an egg clutch by investing different amounts of time and energy towards the eggs. For example, a male could choose to fan less in times of scarcity or fan more in times of abundance. Furthermore, males display increased alertness when guarding more valuable broods, or eggs in which paternity was guaranteed. Females, though, display generally less preference for parental behavior than males. All these suggest that males have increased parental investment towards the eggs compared to females.