DECEMBER 2014 | TRILOBITE TAL ES 15

IMAGING TECHNIQUES FOR STUDIES OF MICROWEAR ON EDESTUS TEETH

by Wayne M. Itano

IntroductionIn 2013 I received a Karl Hirsch Memorial Grant of $500 from WIPS to support a project titled“Functional morphology of Edestus teeth, based onobservations of microwear.” One of the conditionsof accepting the award is to present results of thestudy to the WIPS membership, either as an oralpresentation or an article in Trilobite Tales, withintwo years. This article is meant to fulfill thatrequirement. The research is still in progress. I expect to submit the significant results in theform of an article in a scientific journal, in whichWIPS will be acknowledged. Unlike in a typicalscientific report, I will give some detail as to howthe $500 was used. WIPS does not ask for such anaccounting, but I think it might be of some interestto WIPS members, including those consideringapplying for a grant.

Research question: Edestus is a shark from thePennsylvanian Period that has a unique dentition,consisting of two tooth whorls containing sharp,serrated teeth. It is generally thought that thesetooth whorls acted like scissor blades to cut preycaught between them. The problem with this idea is that the tooth whorls are curved, so that only afew of the teeth can be brought together, and theouter ones don’t seem to be functional. One recentreconstruction is shown in Fig. 1. In thisreconstruction, the shark cannot close its mouth, andmost of the sharp teeth cannot be brought together.

I have proposed a new reconstruction that allowsEdestus to close its mouth, but leaves the toothwhorls extending outside the mouth. Rather thancutting prey between the two tooth whorls, Ipropose that Edestus slashed prey with an up-and-down motion of the entire head, with jaws fixed, asin Fig. 2.

So, which reconstruction is closer to the truth? DidEdestus use its teeth like scissors or to slash?

Figure 1 – A reconstruction of Edestus giganteus.From the 2013 book, “Requins: De la préhistoire ànos jours.” by G. Cuny and A. Bénéteau. Drawingused with permission.

Figure 2 – New idea for the use of the toothwhorls. The head moves up and down, with jawsfixed, to slash prey. This drawing is for Edestusnewtoni. Drawing by Gary Raham.

16 TRILOBITE TAL ES | DECEMBER 2014

Proposed method of answering the question: It occurred to me that, in cutting prey, tiny scratches mighthave been made on the surfaces of the teeth, and the orientation of these scratches might allow one todistinguish between the two possibilities. That is, are there scratches going from the base to the tip ofthe tooth, as in Fig. 3, or across the tooth, as in Fig. 4?

In my proposal, I asked for funds for scanning electron microscope (SEM) imaging of Edestus teeth.SEM imaging is often used in studies of microwear of fossil mammal teeth, but few such studies ofshark teeth have been reported.

SEM ImagingI ran into some problems getting accessto the SEM facilities at the University ofColorado, but I was able to gain accessto SEM facilities at the University ofNorthern Arizona at Flagstaff throughmy connection with Prof. David Elliott,who is a specialist in Paleozoic fishes.As a trial, I asked them to scan parts oftwo teeth of Edestus heinrichi, which Ihad obtained from fossil dealers.

Unfortunately, the results were notconclusive. Some scans showed scratches,but most did not, possibly due to poorpreservation of the surface. Theorientations of the scratches varied buttended to be intermediate between thecases shown in Fig. 3 and Fig. 4. It wasunclear to me why scratches would notbe more uniformly distributed over thesurfaces of the teeth. Worse, I could noteliminate the possibility that some ofthe scratches were due to preparation. For future studies, I have obtained some unprepared Edestus teeththat I can extract from the shale matrix to eliminate that possibility. Figure 5 is one of the SEM scans thatshows scratches. I believe the star-like structures are pyrite crystals.

Cost: 3.25 hours SEM imaging @ $35 = $113.75, Shipping: $4.27, Total: $118.02

Figure 3 – Scratches (in red) expected if the teethare used like scissors.

Figure 4 – Scratches (in red) expected if the teethare used in a slashing mode.

Figure 5 – SEM image of the edge of a tooth crown of Edestusheinrichi. Arrows point to some of the scratches. The scale bar is100 micrometers = 0.1 mm.

DECEMBER 2014 | TRILOBITE TAL ES 17

Manual Scanning Macro PhotographyWhile I was trying to obtain access to theUniversity of Colorado SEM facilities, I spenthours with a binocular microscope examiningsome Edestus teeth borrowed from the VertebratePaleontology Laboratory at the University ofTexas. These were loaned to the University ofColorado Museum, where I could examine them.A few of these teeth had unusually well-preservedsurfaces, and I was able to recognize a few scratchesprobably resulting from preparation by their freshappearance and the fact that they had a crisscrossedpattern. Most of the scatches likely were due towear during life. However, capturing thisphotographically took some experimentation. Iused an Olympus TG-2 camera, which can focusas close as 1 cm, and I obtained from eBay a used,micrometer-driven, precision x-y translation stageto move the specimen horizontally in a preciseway so that I could photograph an entire tooth,in small patches. Free software can then be usedto stitch the patches together into one large image.Figure 6 shows the setup, which is small enoughto be portable. The camera is mounted on a smallcopy stand. The x-y stage is attached to a smalllab scissor jack, which provides vertical positioning.

Figure 7 shows one of the Edestus teeth that displaysclear scratches. The small rectangle marks the limitsof the single photograph shown in Fig. 8. Numerousscratches can be seen in Fig. 8. Their orientationsare mostly in the direction across the tooth, as inFig. 4. I think this provides pretty good evidencefor the “slashing-mode” hypothesis.

The free Fiji image processing software package wasused to stitch together images. An example of astitched-together image is shown in Fig. 10. Suchseamless stitching was only possible because of theuse of the precision x-y stage. The data have notall been analyzed yet.

Cost: Copy stand: $37.26Used Newport precision x-y stage: $105.80(New cost is $500)Lab scissor jack: $55Image stitching software (Fiji): freeTotal: $198.06

I have not included the cost of the camera (about$250), because this was purchased for generalfield and lab use, not just for this project.

Figure 6 – Setup for macro photography with precisehorizontal motion control.

Figure 7 – Edestus tooth from Texas. The small blackrectangle marks the limits of the photo of Fig. 8. Scalebar = 1 cm.

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High dynamic range(HDR) imagingHigh dynamic range (HDR)imaging is a method forcombining photographstaken at different exposuresin cases where no oneexposure produces a goodimage. Consider the twophotographs of an Edestustooth shown in Figs. 11Aand 11B. In Fig. 11A, mostof the tooth is well-exposed,but the recessed area,indicated by the whitearrow, is underexposed.Also, the part deep in thecrack, indicated by the smallred arrow, is almostcompletely dark. In Fig.11B, much of the tooth isoverexposed, but therecessed area and the crackarea are better exposed thanin Fig. 11A. In Fig. 11C,made by using software tocombine five images takenat different exposures, thedark parts are exposed aswell as in Fig. 11B, but noneof the tooth is overexposed.I expect that HDR imagingwill prove useful for manydifficult-to-light specimens.

Cost: Photomatix Prosoftware: $99Total: $99

Figure 8 – Single photograph of the tooth shown in Fig. 7, taken with theapparatus of Fig. 6. Note the many straight scratches roughly perpendicularto the sinuous cracks in the surface.

Figure 9 – Here some of the more prominent scratches of Fig. 8 are markedin white.

DECEMBER 2014 | TRILOBITE TAL ES 19

Figure 10 – Image of part of the tooth shown in Fig. 7, made by stitching together six smaller images.

Figure 11 – Example of HDR imaging of an Edestus tooth. (A) Most of the tooth is well-exposed, but theareas indicated by the white arrow and the red arrow are underexposed. (B) The areas that are dark in Fig.11A are better exposed, but much of the rest of the tooth is overexposed. (C) Photo made by combiningdata from five different exposures. The result is better exposed overall.

ConclusionSo far, the expenditures related to this project are $415, which leaves $85 of the original $500, enoughfor a couple of hours of SEM time. This project is part of my ongoing studies of Edestus, which hasresulted, so far, in the following publications (as well as various newsletter articles, conferenceabstracts, posters, and talks):

Itano, W. M., 2014, Edestus, the strangest shark? First report from New Mexico, North Americanpaleobiogeography, and a new hypothesis on its method of predation: Mountain Geologist, v. 51, no. 3,p. 201-221.

Itano, W. M., 2014, A tale of two holotypes: rediscovery of the type specimen of Edestus minor:Geological Curator, vol. 10, no. 1, p. 17-26.

Itano, W. M., 2013, Abnormal serration rows on a tooth of the Pennsylvanian chondrichthyan Edestus:New Mexico Museum of Natural History and Science Bulletin, v. 60, p. 139-142.

Itano, W. M., 2013, A tooth of Edestus from the early Pennsylvanian of Cheshire, UK: Proceedings ofthe Yorkshire Geological Society, v. 59, no. 3, p. 187-194.

Itano, W. M., submitted, An abraded tooth of Edestus (Chondrichthyes, Eugeneodontiformes): evidencefor a unique mode of predation: Transactions of the Kansas Academy of Science.

Itano, W. M., Houck, K. J., and Lockley, M. G., 2012, Systematics and occurrences of Edestus(Chondrichthyes) worldwide and new occurrences from Colorado and Texas: Historical Biology, v. 24,no. 4, p. 397-410.

Itano, W. M., and Lucas, S. G., in press, The youngest record of Carcharopsis (Chondrichthyes) fromthe Pennsylvanian of Xinjiang Uyghur Autonomous Region, China: Palaeoworld.

About the AuthorWayne Itano is a charter member of WIPS and a scientist emeritus at the National Institute ofStandards and Technology (NIST). An article about Wayne’s involvement in avocational paleontologywas recently featured in the NIST Connections newsletter. You can read the article on Wayne’sacademia.edu website: https://www.academia.edu/9251238/How_I_found_a_second_scientific_career

20 TRILOBITE TAL ES | DECEMBER 2014

Paleo Funnies by Steve Wagner

This month’s paleo-related humor comes straight from The Onion®, a satirical newsorganization. Click the headline or the link below to read the article.

Paleontologists Determine Dinosaurs Were Killed By Someone They Trusted

The Onion, ISSUE 50•46 – November 17, 2014http://www.theonion.com/articles/paleontologists-determine-dinosaurs-were-killed-by,37468/

TRILOBITETALES

DECEMBER PROGRAM:HOLIDAY AUCTION &POTLUCK PARTY

Saturday, December 13, 2014, 5:30 p.m.Lutheran Church of the Master, Lakewood

Bring items to sell. Bring some food. Bring some friends. Bringyour checkbook! The WIPS holiday auction and potluck is comingup soon. So get out your quality—but unwanted—fossils, minerals,books, maps, dino toys and the like to enrich someone else’s mantel.And, of course, be ready to bid on items to fill up your ownmantel. Funds raised go toward WIPS grants and scholarships.

Auction hours are:5 p.m. – Doors open for set up5:30 p.m. – Sellers start putting out items6:30 p.m. – Devouring of comestibles7 p.m. – Silent and tin can auctions start8 p.m. – Tin can auction ends; verbal auction starts9-9:30 p.m. – Silent auction ends; checkout starts.10 p.m. – Shut down and clean up

There are two types of bid sheets again this year: the historic formsdesigned for fossils and another designed for books and maps.Copyable versions are at the end of this issue. Fillable versions arealso on the WIPS website as .pdf or .xls files. (Pre-typed forms areSO MUCH easier for the treasurer to read.)

More information is on page 5. Questions? Contact Dan Winester,deadfishrman@aim.com

VOLUME 32, NUMBER 9DECEMBER 2014

In This Issue

NOVEMBER ELECTION RESULTS . 4

HOLIDAY AUCTION DETAILS . . . 6

FIELD NOTES: COMANCHE

NATIONAL GRASSLAND . . . . . . 13

GRANT RECIPIENT REPORT:Imaging Techniques for Studies ofMicrowear on Edestus Teeth . . . 15

DEPARTMENTS

President’s Message . . . . . . . . . 2Announcements/Member News 3Science Events Calender . . . . . 7Founders Symposium 2015 . . .10Member Profile: Robert Grow .15Paleo News . . . . . . . . . . . . . . .14Science Stew . . . . . . . . . . . . . .21

FOR YOUNGER MEMBERS

Fossil Club for Kids . . . . . . . . . 8

s

Stegosaurus, the Colorado State Fossil, Art © Shannon S. Yeager

Page 15

Trilobite Talesis the official publication of theWestern Interior Paleontological

Society (incorporated January 22,1985). Meetings are held the firstMonday of each month at 7 p.m.,

except June, July and August, at theDenver Museum of Nature &Science, Denver, Colorado.

Editor: Susan PassmoreEditor Emeritus: Lynne Clos

Newsletter CommitteeDistribution: Kathy Brill

Assistant Editor: Gary RahamCopy Editor: Jude Burton

Proofreaders: Malcolm Bedell, Jr.,Steve Wagner, Dan Winester

MISSION The purposes of theSociety shall be scientific,

educational, and charitable andshall include field trips, lectures,

seminars and other educational andscience-related activities; the

making available of information asto exploring for, identifying,preparing, preserving, and

displaying fossils; encouragingadherence to responsible codes ofconduct in the exploration for andcollection of fossils; assisting museumsand educational institutions in thefurtherance of their paleontology-related activities; and cooperating

with government authorities in thedevelopment of laws governing the

collection of fossils and theirpreservation for future generations.

MEMBERSHIP Annual calendar yeardues are $25 for an individual or

$30 for a family.

ADVERTISING Monthly rates: full-page $30, half-page $20,

third page $10, quarter page $8,business card $4. Info:

newsletter@westernpaleo.org

WESTERN INTERIOR

PALEONTOLOGICAL SOCIETY

P.O. BOX 200011 DENVER, COLORADO 80220-0011

WESTERNPALEO.ORG

From the President

This is my last President’s Message.It is hard to believe the year passed byso quickly. Dan Winester has volunteeredto fill the open position of First VicePresident and will automaticallyassume the President’s office in 2015.The WIPS Board unanimously

approved Dan for this leadership role.

As I reflect on this past year, some of the WIPS highlights have included:

• Great monthly speakers taking us on a fossil journey from Colorado toNorth Dakota, Montana, Kansas, and California.

• Field trips and field opportunities to Corral Bluffs, northern NewMexico, Baculite Mesa, Florissant, Utah, and the ComancheGrasslands

• Outreach to the community at the Denver Gem and Mineral Show andfor National Fossil Day at the Denver Museum of Nature and Science.

• The Fossil Club where kids learn more about fossils and paleontology.

• Organizing the Stories in Stone symposium for the public.

I want to thank those who have served WIPS this past year on theBoard. Committee chairs and members, field trip leaders, and speakersmake WIPS an educational and fun group. A special thank you goes toSteve Miller and Shellie Luallin, who are retiring from the Board at theend of the year. Both have served on the Board for a number of yearsand their experience and enthusiasm will be missed. However, we havefive new members joining the Board. Ann Kusic was elected Secretary.We have not had a Secretary this past year and appreciate Annvolunteering to fill this position. Those who were at the election inNovember will remember that we had three open Board Director positionswith four candidates. There was a tie for the third seat, so the Boarddecided to expand the number of directors to four. We welcome BlakeSullivan, Jim Weedin, Dawn Grow, and Amber Cain to next year’s Board.

What’s in store for next year at WIPS?• Founders Symposium – always a great weekend• More field trips• Great meeting speakers• Educational classes• Public outreach opportunities

2015 will be a great year.

2 TRILOBITE TAL ES | DECEMBER 2014

Dennis Gertenbach

– Dennis Gertenbach, Presidentwips.pres@westernpaleo.org

303-709-8218