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<DIV class=journal-title>Nature</DIV>
<DIV><ABBR
title="Digital Object Identifier">doi</ABBR>:10.1038/nature.2012.10385</DIV>
<DIV class=article-heading> </DIV>
<DIV class=article-heading><FONT size=4>Tooth surfaces reveal what fish
ate</FONT></DIV></HGROUP>
<DIV>Species can be distinguished through microscopic analysis of the wear and
tear on their teeth.</DIV>
<DIV><SPAN class=vcard><A class=fn
href="http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410#auth-1">Leila
Haghighat</A></SPAN></DIV>
<DIV class=pubdate-and-corrections><TIME datetime="2012-04-04" pubdate>04 April
2012</DIV>
<DIV class=pubdate-and-corrections><A
href="http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410">http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410</A></DIV>
<DIV class=pubdate-and-corrections> </DIV>
<DIV class=pubdate-and-corrections>
<DIV class=article-tools>By analysing the roughness of a single tooth using
three-dimensional (3D) imaging, scientists can now identify what a fish has
eaten. They can use this information to classify species more quickly and easily
than with standard methods.</DIV>
<P>Mark Purnell, a palaeobiologist at the University of Leicester, UK, and his
colleagues took advantage of advances in a technique called microtextural
analysis. “Until recently, quantification of surface roughness used a
two-dimensional approach comparable to a gramophone, recording up and down
profiles by dragging a stylus across the surface,” he says.</P>
<P>But now, researchers can use a focus-variation microscope to build up a 3D
picture. The technique was designed for industry, and has been used to analyse
the surfaces of products ranging from hip replacements to chocolate.</P>
<P>The microscope maps the peaks and troughs of a surface, revealing patterns of
wear. “Studying the roughness of teeth is like studying a landscape,” says
Purnell.</P>
<P>His team looked at the teeth of cichlid fish collected from Lake Victoria in
East Africa. The results are published today in the <I>Journal of the Royal
Society Interface</I><SUP><A id=ref-link-1 class=ref-link
title="Purnell, M., Seehausen, O. & Galis, F. J. R. Soc. Interface http://dx.doi.org/10.1098/rsif.2012.0140 (2012)."
href="http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410#b1">1</A></SUP><I>.</I></P>
<P>Cichlids are known to have evolved rapidly into many different species
adapted to a wide range of diets. Three of the species examined in the study eat
algae using 'oral teeth' in the mouth: two, <I>Neoc</I><I>hromis gigas</I> and
an unnamed species from the genus <I>Haplochromis</I>,<I> </I>graze off
rocks.<I> </I>The third, another species of <I>Haplochromis</I>, scrapes algae
off plants.</P>
<DIV class="content no-heading cleared main_content">
<P>The researchers also studied <I>Astatoreochromis alluaudi</I>, which crunches
molluscs using pharyngeal jaws further down the throat. They compared the teeth
of wild fish with those of animals fed a softer diet in the laboratory.</P>
<P>The team could identify the fish species from their teeth more accurately
using 3D microtextural analysis than they could using two-dimensional
techniques. But Purnell thinks that until the 3D method has been verified with
larger sample sizes, the approach will remain complementary to existing
methods.</P></DIV></DIV>
<DIV class=pubdate-and-corrections>
<DL class=citation>
<DD class=journal-title></TIME></DD></DL></DIV></HEADER><SECTION>
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<DIV style="WIDTH: 302px" class="img img-right">
<DIV
style="PADDING-BOTTOM: 1px; PADDING-LEFT: 1px; PADDING-RIGHT: 1px; PADDING-TOP: 1px"
class=img-content><IMG alt=""
src="http://www.nature.com/polopoly_fs/7.3783.1333470877!/image/MarkPurnell_edit.jpg_gen/derivatives/landscape_300/MarkPurnell_edit.jpg">
<P class=caption><FONT size=1>Three-dimensional analysis reveals the distinctive
wear on teeth. </FONT><FONT size=1>Mark Purnell</FONT></P></DIV></DIV>
<DIV class=article-tools>One existing method is time-consuming and unpleasant:
sifting through stomach contents to determine what an animal has eaten.
Microtextural analysis is much more convenient, and also offers another
advantage — stomach contents vary from day to day, whereas tooth wear reveals
long-term patterns of diet.</DIV></DIV>
<DIV class="content no-heading cleared main_content">
<P>The technique could allow researchers to analyse fossilized teeth to show
what extinct animals ate. Purnell's team is currently studying aquatic organisms
including plesiosaurs.</P>
<P>“Our ancestors were fish and ‘non-chewers’ for about as long as they were
mammals," says Peter Ungar, a palaeoecologist at the University of Arkansas in
Fayetteville. Microtextural analysis "can teach us about our very distant
pre-mammalian ancestors and others that lived during the first half of
vertebrate evolution”, he says.</P>
<P>Gildas Merceron, a palaeobiologist at the Claude Bernard University of Lyons
1 in France, has conducted similar work on antelopesand apes<SUP><A
id=ref-link-2 class=ref-link
title="Ungar, P. S., Merceron, G. & Scott, R. S. J. Mammal. Evol. 14, 163–181 (2007)."
href="http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410#b2">2</A>,
<A id=ref-link-3 class=ref-link
title="Merceron, G., Kaiser, T. M., Kostopoulos, D. S. & Schulz, E. Proc. R. Soc. B 277, 3105–3112 (2010)."
href="http://www.nature.com/news/tooth-surfaces-reveal-what-fish-ate-1.10385?WT.ec_id=NEWS-20120410#b3">3</A></SUP>.
He notes that teeth could also record seasonal and gender variation in
diet.</P></DIV>
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