Fossil Friday #8 – Science Literacy Week

It’s Science Literacy Week here in Canada, so in celebration, this week’s Fossil Friday post is a short compilation of some great books and reading resources for anyone interested in palaeontology, ecology, evolution, and even the Canadian Rockies.

Here’s a list of some of my favourite natural science related books:

(1) A Natural History of Shells.
Vermeij, G. J. 1993. Princeton University Press, Princeton, New Jersey.

This one is probably my favourite textbooks of all time.  If you like evolution, palaeontology, or ecology, go read everything by Geerat Vermeij.  He is a genius and arguably one of the top scientists in the world right now.

Image result for A Natural History of Shells book

 

(2) Fossil Invertebrates
Richard S. Boardman, R. S., Cheetham, A. H., and Rowell, A. J. 1987. Blackwell Scientific Publications, Oxford.

There is another book by the same title published by Taylor and Lewis in 2007.

(3) Fossil Invertebrates
Taylor, P. D., and Lewis, D. N. 2007. Harvard University Press, Cambridge, Massachusetts.

Paul Taylor is another leader in the field, and has done a lot of work on encrustation/biotic interactions.  I recommend many of the papers he and Mark Wilson have written.

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(4) Invertebrate Palaeontology and Evolution.
Clarkson, E. N. K. 4th edition. 2008. Blackwell Scientific Publications, Oxford.

Image result for invertebrate palaeontology and evolution clarkson 4th edition

 

(5) Geographical Ecology: Patterns in the Distribution of Species.
MacArthur, R. H. 1984. Princeton University Press, Princeton, New Jersey.

This one is pretty math-heavy, but it is considered a classic, and one of the last things MacArthur wrote (he died quite young). MacArthur was another genius and is generally regarded as the top ecologist of all time (he, along with E. O. Wilson, came up with major ecological theories, such as island biogeography).

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(6)Predator-Prey Interactions in the Fossil Record.
Eds. Kelley, P. H., Kowalewski, M., Hansen, T. A. 2003. Kluwer Academic/Plenum Publishers, New York, New York.

Full of really interesting chapters on a large variety of animals from a lot of different authors.

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(7) Handbook of the Canadian Rockies
Gadd, B. reprint 2016. Corax Press, Canmore, Alberta.

I’ve included this one because it covers everything from plants, to birds, to geology, and even humans!  Great for a general audience, and a super fun, informative, and entertaining read!

 

(7) Living and Fossil Brachiopods.
M. J. S. Rudwick. 1970. Hutchinson University Library, London

A must-read for anyone studying brachiopods.  It might be a bit outdated, but it is very comprehensive and easy to read.

Image result for Living and fossil brachiopods rudwick

There are lots of other classics out there, such as anything by S. J. Gould, M. Rosenzwig, etc., etc., etc.

What are you reading right now?  Anything to add to my list?  Leave me a comment, and happy reading!

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Fossil Friday #7 – Predation and Repair Scars

Last week, I introduced the topic of studying predation in the fossil record, and some of the kinds of traces, such as drill holes, we can look at to give us clues as to how predators and prey interacted in the past.

Another kind of predation trace that we use in invertebrate palaeontology is called a repair scar.  Repair scars are generated when a durophagous (shell-crushing) predator, such as a crab or fish, attack a shelled animal, but for some reason, fail to kill the prey.  If the shelled animal is able to avoid being eaten, it will start to repair the damage to its shell, resulting in a visible scar where its shell was damaged.  It is essentially the same as the callus that develops on a broken bone after it heals.  Here is a picture of a snail with a large repair scar caused by a crab inserting the tip of its claw into the shell and peeling it back (like how you would peel an orange).  I’ve outlined the scar on the right image.

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Predator – Red Rock Crab (Cancer productus)

Wait a second.  Why would you study failed predation in the fossil record?  Why wouldn’t you study successful predation?  If you think about the nature of crushing predation, a successful attack is likely going to destroy most or all of the shell.  It is much less likely for shell fragments to be preserved, and good luck trying to find or fit all of the shell bits back together.  That kind of preservation just doesn’t happen (Stafford and Leighton, 2011).  Although, check out a recent paper by members of our lab on a creative way to deal with all of the fragments, at least in the modern (Leighton et al. 2016).

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A rare example of an intact, successfully peeled snail (Nucella lamellosa).  A shell like this is usually destroyed by the predator, and unlikely to preserve in the fossil record, even in this state.

So how can we know that repair scars, or failed attacks, are actually an accurate proxy for how much predation actually occurred?  This is where studies of modern ecosystems come in very handy, and one of the reasons that our lab spends half of its time studying live ecosystems, even though we are palaeontologists.

When I was a Master’s student, I took a research class out at Bamfield Marine Sciences Centre where we looked at the rate of repair scars on populations of a common snail (Tegula funebralis – we called it Chlorostoma funebrale in the paper, but the name has since changed) (Molinaro et al. 2014).  We collected the Tegula from eight different sites that we knew had different levels of predation based on previous studies, which had shown that the rate of crab predation strongly correlates with the environmental energy (quiet water settings have high levels of crab predation, whereas wave-dominated water settings have very low rates of crab predation) (Robels 1987; Robels et al. 1989).  We found that there was a strong inverse relationship between repair scar frequency and the energy in the system.  In other words, we found the highest rates of predation in quite water settings, where there were more crabs, which corroborated our hypothesis that repair scars accurately reflect the rate of predation in a system.

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A giant repair scar on a modern snail (Tegula funebralis).

 

Knowing that repair scars are an accurate proxy for the rate of predation allows us to ask all sorts of interesting questions, both in the modern, and in the fossil record.  We can answer simple, but important questions about how many predators there were in a system (Stafford et al. 2014), or how and why the rates of predation differ between places or time (Leighton, 2002). We can also look at more specific problems, such as whether reaching a certain size can prevent a predator from being able to crush you (Richards and Leighton 2012), or how the development of spines can make it impossible for crushing predators to grab prey (Linge-Johnsen et al. 2013), and what it all might mean for the evolution of both predator and prey (Vermeij 1987).

Repair scars on brachiopods.  Figure 3 (Richards and Leighton 2012).

I am actually going to be looking at predation and repair scars on a couple of different snails and their ancestors for much of my dissertation, and will be using things like repair frequency to help me determine predation pressure along the modern and recent coast of the Pacific Northwest, and throughout the Plio-Pleistocene.  My goal is to see how ocean acidification affects interactions between predators and prey through time, so tracking changes in repair scars will be helpful might indicate if there are changes in predation rates, or at least failed predation.

References:

Leighton, L. R. 2002. Inferring predation intensity in the marine the fossil record. Paleobiology. 28:328-342.

Leighton, L. R., Chojnacki, N. C., Stafford, E. S., Tyler, C. L., and Schneider, C. L. 2016. Categorization of shell fragments provides a proxy for environmental energy and predation intensity. Journal of the Geological Society. 173:711715.

Linge-Johnsen, S. A. Ahmed, M., and Leighton, L., R. 2013. The effect of spines of a Devonian productide brachiopod on durophagous predation. Palaeogeography, Palaeoclimatology, Palaeoecology. 375:30–37.

Molinaro, D. J., Stafford, E. S., Collins, B. M. J., Barclay, K. M., Tyler, C. L., Leighton, L. R., 2014. Peeling out predation intensity in the fossil record: A test of repair scar frequency as a suitable proxy for predation pressure along a modern predation gradient. Palaeogeography, Palaeoclimatology, Palaeoecology. 412:141-147.

Richards, E. J., and Leighton, L. R. 2012. Size refugia from predation through time: a case-study of two Middle Devonian brachiopod genera. Palaeogeography, Palaeoclimatology, Palaeoecology. 363 – 364:163-171.

Robels, C. 1987. Predator Foraging Characteristics and Prey Population Structure on a Sheltered Shore. Ecology. 68:1502 – 1514.

Robels, C. Sweetnam, D. A., Dittman, D. 1989. Diel variation of intertidal foraging by Cancer productus L. in British Columbia. Journal of Natural History. 23:1041 – 1049.

Stafford, E. S., and Leighton, L. R. 2011. Vermeij Crushing Analysis: A new old technique for estimating crushing predation in gastropod assemblages. Palaeogeography, Palaeoclimatology, Palaeoecology. 305:123 – 137.

Stafford, E. S., Tyler, C. L., and Leighton, L. R. 2014. Gastropod shell repair tracks predator abundance. Marine Ecology. 36:1176 – 1184.

Vermeij, G. J. 1987. Evolution and Escalation. Princeton University Press. Princeton, New Jersey.

 

Fossil Friday #6 – Predation and Drill Holes

Predation is a pretty big topic in palaeontology, but not as straight forward as you might expect.  We all have this image in our head of the T. rex from Jurassic Park feasting on another dinosaur (or perhaps the lawyer on the toilet), but where does that information come from?  Unlike in Jurassic Park, humans were never alive to actually witness a T. rex eating a Triceratops, so how can we be certain those interactions ever occurred?

Anti-predatory adaptations, such as armour, spikes, frills, are a good first clue that something is trying not to be eaten.  Even better, though, is the actual evidence of an interaction preserved on the hard parts of either predator, or (more often) prey.  For example, there is a really nice specimen of a Triceratops at the T. rex Discovery Centre in Eastend, SK, where you can see tooth marks from a predator.

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Tooth marks in bone (T. rex Discovery Centre, Royal Saskatchewan Museum, Eastend, SK)

Unfortunately for vertebrate palaeontologists, bigger animals are not as abundant, so the occurrence of such fossils is really special and rare.  With invertebrate palaeontology, we have a bit of an easier time.  One type of predation trace preserved on invertebrate prey is called a drill hole, which is a hole in the shell of a prey animal created by predatory gastropods (snails).

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Fossil bivalve shell with drill hole from a predatory snail (Pinecrest Fm., Late Pliocene)
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Drilled fossil gastropods from the Pinecrest Fm. (Late Pliocene, Florida)

If you remember my post about cone snails, I mentioned that gastropods have a special feeding organ called a radula, which is usually rough like a cat’s tongue and used for scraping food.  In the case of drilling gastropods, they have another organ called an accessory boring organ (ABO), which secretes material to soften the shell of their prey as they scrape with their radula.  One of the more common predatory snails is called a naticid (moon snail).  They can get to be very large (bigger than a softball), and have a giant foot that they use for both moving, and grappling their prey.

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A fossil naticid (moon snail) from the Pinecrest Fm. (Late Pliocene)

 

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A live naticid with its giant foot of nightmares. Image credit: https://upload.wikimedia.org/wikipedia/commons/9/9c/Neverita_didyma.jpg

Drill holes can be used to study many aspects of predation and predator-prey dynamics.  For example, we can look at how often prey are being attacked and see if there are predator preferences (Yanes and Tyler 2009).  Or perhaps there is evidence of anti-predatory adaptations, such as spines (Leighton 2001), or a lack of edible parts (Tyler et al 2013).  Drill holes can even be used for taphonomic studies (everything that happens from the moment an animal dies to the time the fossil is discovered), such as how drill holes affect the transportation and deposition of shells (Molinaro et al. 2013).  drill-hole-2

Predators are not always successful, and will sometimes get interrupted, perhaps even by a predator of their own.  Such interruptions produce incomplete drill holes, which can also be used to determine the success rates of predators, or the intensity of predation upon the drillers themselves (Chattopadhyay and Baumiller 2010).

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Incomplete drill hole on a modern naticid.

Some predators will even recognize different prey types and attack each in a particular manner, producing sterotypic drill holes that are in a consistent location unique to that prey (Leighton 2001).  Not only that, but they can be highly cannibalistic, and will often eat smaller members of their own species (Chattopadhyay et al. 2014).  Basically, if they are able to grapple you with that huge foot, you are in trouble.

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Stereotypy of drill holes in smaller, modern naticids (cannibalized)

TL,DR: Drill holes have an extensive fossil history, and are very useful for studying predator-prey dynamics and how predation has evolved.  Stay tuned for a future blog post on another type of predation trace: repair scars…

References:

Chattopadhyay, D., and Baumiller, T. K. 2010. Effect of durophagy on drilling predation: a case study of Cenozoic molluscs from North America. Historical Biology. 22:367-379.

Chattopadhyay, D. Sarkar, D., Dutta, S., Prasanjit, S. R. 2014. What controls cannibalism in drilling gastropods? A case study on Natica tigrinaPalaeogeography, Palaeoclimatology, Palaeoecology. 410:126-133.

Leighton, L. R. 2001. New example of Devonian predatory boreholes and the influence of brachiopod spines on predator success. Palaeogeography, Palaeoclimatology, Palaeoecology. 165:54-69.

Molinaro, D.J., Collins, B.M.J., Burns, M.E., Stafford, E.S., Leighton, L.R. 2013. Do
predatory drill holes influence the transport and deposition of gastropod shells?
Lethaia. 46:508–517.

Tyler, C. L., Leighton, L. R., Carlson, S. J., Huntley, J. W., Kowalewski, M. 2013. Predation on modern and fossil brachiopods: assessing chemical defenses and palatability. Palaios 28:724-735.

Yanes, Y., and Tyler, C. L. 2009. Drilling predation intensity and feeding preferences by Nucella (Muricidae) on limpets inferred from a dead-shell assemblage. Palaios 24:280-289.

Fossil Friday #5 – Parker Ridge: Columbia Icefield Parkway

I’ve been on the go for most of August, with outreach commitments, holidays, and field work in the States, so I’ve missed a few Fossil Fridays.  But even while on holidays, I was documenting some neat stuff that I discovered.

Our family went on a road trip through the Canadian Rockies (which I highly recommend), starting in Edmonton, then out the Jasper, down through the Columbia Icefields and Icefields Parkway, through Lake Louise, Banff, and Canmore, and ending in Cochrane.  We had a blast, and spent most of our time hiking mountain trails (I’m hugely proud of both of my parents for keeping up with my sister, husband, and myself).  As Canadians, we sometimes forget the amazing places we can holiday right in our own backyard.  Not to mention, there are incredible geologic features everywhere in the Rockies…

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At the top of Whilsters Mountain, Jasper, AB

One of my favourite hikes was Parker Ridge Trail (Banff National Park), just a few kilometres south of the Athabasca Glacier and Columbia Icefield Discovery Centre (which, by the way, has a really awesome little hotel).  The trail itself was about a 5 km round trip, with switchbacks up to the top of Parker Ridge, and then a couple of trails to explore along the top of the ridge.  You are rewarded at the top with some pretty spectacular views, including Mount Athabasca to the North, and the Saskatchewan Glacier and valley.

Map of the Icefield Parkway and the first part of Parker Ridge Trail. Image credit: http://jasperjournal.com/hiking/parker-ridge-trail-hiking-in-banff-national-park-on-the-jasper-border
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View from the top of Parker Ridge (Saskatchewan Glacier and mouth of the North Saskatchewan River).

I had been on the hunt for good fossils the entire trip, but despite visiting units that I knew were fossiliferous, I had come up mostly empty handed (except for a few really scrappy gastropods).  Within a few hundred metres of starting out on Parker Ridge Trail, I finally started seeing fossils.  Lots of them.  Most were a type of branching rugose coral of the family Phillipsasteidae (likely Thamnophyllum), with a smattering of another group of corals called favositids (I think maybe Thamnopora and/or Alveolites).  There was also the occasional gastropod (snail).

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Typical rugosan corals (likely Thamnophyllum)
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Another “massive” rugose coral.
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A different branching coral (maybe a favositid?)
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Some cut-through (transverse) views of gastropods.

From the look of the rock (limestone), and types of corals, I was pretty sure we were in the Devonian (who would have thought that fieldwork and grad school would pay off in accurate hunches!).  And so began my hunt for the one type of fossil that would convince me of the age of the rock: atrypide brachiopods.  If you’ve been reading my blog, you might remember that I did my undergrad and master’s theses on atrypide brachiopods (check out my post on brachiopods, and another on my favourite little fossil, the Champ).

We were about two thirds of the way back down, and in a hurry because it had started to rain, when I basically tripped over them.  Two little atrypide brachs, which I’m pretty sure were Desquamatia (Independatrypa) independensis (and when I say pretty sure, I will admit that I might be totally wrong about the coral IDs, but just trust me that I’m one of about 10 people that can ID atrypide brachiopods, because they are really darn hard to ID).

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Finally!  Some brachiopods!  (Desquamatia (Independatrypa) independensis)

Given all of the fossils, the rock would be from the Upper Devonian (Frasnian), making the formation about 380 – 370 million years old.  I later looked up some AGS maps and other papers to confirm (see references below).  Bascially, Parker Ridge Trail is great for fossil and hiking enthusiasts alike, and you should add it to your list of spots to visit.

IMPORTANT NOTE: It is illegal to remove or damage rocks or fossils in Canada’s national parks, so you can look, but not take.

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Rocks, glaciers, and fossils = happy vacationing palaeontologist

References:

McLean, R. 2005. Phillipsastreid corals from the Frasnian (Upper Devonian) of Western Canada: taxonomy and biostratigraphic significance. National Resource Council of Canada, Ottawa, Ontario.

Pana, D.I. and Elgr, R., comp 2013. Geology of the Alberta Rocky Mountains and Foothills. Energy Resources Conservation Board, ERCB/AGS Map 560, scale 1:500 000.

Smith, S. 1945. Upper Devonian corals of the Mackenzie River region Canada. Geological Society of America Special Papers. 59:1-121.