BookendsThe word

GETTING to grips with the fossil record

can be a headache. When it comes to

understanding how the various

species fit in, palaeontologists need

patience, creativity – and a touch of

humour. Take the seemingly clear-cut

case of extinction which, it turns out,

isn’t always as clear-cut as you might

think. Animals that have apparently

vanished from the fossil record can

seem to reappear after a long hiatus.

Often the vanished creature or a close

relative has indeed returned.

Sometimes, though, the new

discovery is a different species entirely,

but closely resembles one that went

before. Palaeontologists describe such

a case as an Elvis taxon.

A taxon is any type of biological

group, but how did Elvis enter the

palaeontological vocabulary? The story

starts in 1983 with another piece of

inventive categorisation, when David

Jablonski and Karl Flessa gave the

name “Lazarus taxon” to creatures

that reappeared in the fossil record

after a long absence. Unlike the

biblical story, in which Lazarus was

raised from the dead, no one thought

miracles were involved, just gaps in

the fossil record. Normally it is

assumed that a taxon is gone for

good if no trace is found for millions

of years, but it may merely have

become rare, or moved somewhere

where it left no fossils. This is what

happened with the coelacanth, a

fish closely related to amphibians,

which palaeontologists thought had

died out with the dinosaurs until a

South African trawler caught a living

one in 1938.

So where does Elvis come in?

Evolution sometimes converges,

shaping different taxa so they look

very much alike. For example, a

number of distinct lines of predators

have evolved the long, curved and

deadly teeth best known from the

sabre-toothed tiger of the Ice Age.

Some invertebrates evolve shells that

look like earlier forms. These can all be

mistaken for Lazarus taxa until closely

examined. To emphasise the

distinction, Doug Erwin and Mary

Droser coined an alternative term for

imitators in 1993: “Rather than

continue the biblical tradition favored

by Jablonski, we prefer a more topical

approach and suggest that such taxa

should be known as Elvis taxa, in

recognition of the many Elvis

impersonators who have appeared

since the death of The King.” (Palaios, vol 8, p 623)

Like Lazarus taxon, the term caught

on. So have others, created in a similar

vein, such as the “Zombie effect”,

which applies when hard fossils such

as dinosaur teeth are washed out of

sediments and deposited in rocks

millions of years younger – so in a

sense they become walking dead.

Palaeontologists are still looking

for a “Jimmy Hoffa taxon”, a label that

doctoral student Roberto Takata

suggested to the Dinosaur Mailing List

to describe so-far-undiscovered bones

that must be hidden somewhere,

invoking the case of the erstwhile head

of US labour union the International

Brotherhood of Teamsters, who

disappeared in 1975 but whose body is

yet to be recovered. ●

Elvis taxon

“Evolution sometimes shapes different groups to look alike”

TAM

I CH

APP

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S/CO

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IS

EnigmaAussie RulesNo. 1424 Richard England

IN Australian Rules football a score is worth 6

points or 1 point. The cheerleaders wave

their pompoms each time their team scores,

and the number of waves is equal to the

number of points that their team has so far

scored. So if their team first scored 1 point they

would give one wave and if it then scored

6 points they would then give seven waves.

In a recent match the team did not do

very well since the total number of waves

that the cheerleaders gave was less than 50.

If I told you what that total number of waves

was, you would deduce that the number of

occasions on which they waved could be

any of three different possibilities. Even if

I then told you on how many occasions they

waved, you could still find three different

orders of 6s and 1s scored that would have

led to that total number of waves.

(a) On how many occasions did they

wave? (b) What was the total number of

waves?

£15 will be awarded to the sender of the first

correct answer opened on Wednesday

7 February. The Editor’s decision is final.

Please send entries to Enigma 1424, New

Scientist, Lacon House, 84 Theobald’s Road,

London WC1X 8NS, or to enigma@

newscientist.com (please include your

postal address). The winner of Enigma 1418

is John Dolan of London, UK.

Answer to 1418 Non-scoring runners

The positions of the non-scoring runners in

the second team were 12th and 14th.

Biotech revolutionDNAby Frank H. Stephenson, Prometheus, $26/$18.99, ISBN 159102482XReviewed by Bernard Dixon

HERE’S a spirited

riposte to those

who argue that

molecular biology

and genome

mapping will never

make major

contributions to human well-

being. From recombinant drugs

that have already saved so many

lives and ameliorated even

more, to the battle against

unconquered foes such as

malaria, Stephenson portrays

biotechnology as a uniquely

powerful way of understanding,

diagnosing, treating and

preventing disease. He also

shrewdly handles the more

negative developments. Crisply

written in 40 mini-chapters, it

makes a vivid introductory

guide to an ongoing revolution.

Earthly obsessionRichter’s Scaleby Susan Elizabeth Hough, Princeton University Press, $27.95/£17.95, ISBN 0691128073Reviewed by Kate Ravilious

THE name Richter

goes hand in hand

with earthquakes,

but who was the

man behind the

famous scale?

Hough introduces

us to an awkward but brilliant

scientist, passionate about

poetry, nudism and Star Trek.

His obsession with earthquakes

stretched to a seismometer in his

living room. As is fashionable

for geniuses these days, Hough

post-diagnoses him with a

mental disorder and speculates

about his personal relationships.

It’s a shame the book spends so

long on this; when it gets to

Richter’s work and the science of

earthquakes it is fascinating.

48 | NewScientist | 6 January 2007 www.newscientist.com

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