December 2025 ESRFnews
14
scan bigger fossils faster and with sharper detail
Published last year Panciroli and colleagues study
of the pair of fossils from Skye is just one of the recent
standouts of the latest palaeontology Both of the
fossils turned out be Krusatodon kirtlingtonensis an
extinct mouselike creature that lived on Skye about
166 million years ago Additional measurements of the
growth lines in the specimens teeth at the Swiss Light
Source gave an estimate of the ages at death 7 years old
for the adult specimen and up to 2 years old for the
juvenile Compared with modern small mammals this
was surprisingly old for a juvenile – yet it still had its
baby teeth (Nature 632 815). “Today’s mice and shrews
generally don’t live for more than a year or two,” says
Panciroli. “Why did their lives speed up?”
Possibly modern mammals had to live faster as
their blood became warmer and their metabolisms
quickened. Possibly they had to compete with other
environmental pressures. Back in the Middle Jurassic,
says Panciroli, early relatives of mammals such as K.
kirtlingtonensis may have had the benefit of dominating
an otherwise untapped, small-scale ecospace, while the
huge dinosaurs fought among themselves overhead. But
such hypotheses will need to gather support from other
studies. Panciroli, who is already a longterm ESRF
user, expects that she will continue to come to BM18 to
perform more phase-contrast tomography.
Skye isn’t host only to mammaliaforms, though. It
also preserves some of the earliest known relatives of
modern lizards, and, as with mammals, palaeontologists
are keen to know when the defining traits of this group
first emerged. In 2022, Panciroli’s colleagues came
to ID19 with Bellairsia gracilis, a tiny stem-lizard she
found on Skye that had a mix of primitive and modern
features. The images helped to establish that certain
skull characteristics seen in modern geckos – such as the
absence of the jugal bone – were not ancestral features,
as some other researchers had believed, but traits present
in much earlier lizards (Nature 611 99).
Yet another Skye fossil studied this year by Roger
Benson and colleagues at the American Museum of
Natural History in New York broadens the picture
by redrawing the family tree of squamates to which
lizards belong Breugnathair elgolensis had snake
like jaws and teeth not unlike a pythons and closely
resembled fossils from an extinct fragmentary group
known as parviraptorids which were once thought to
include the earliest snakes On the other hand it had
legs and the body proportions of a lizard Carefully
studying synchrotron images from ID19 Bensons team
could show that parviraptorids were not early snakes at
all but stemsquamates early offshoots that predate
PALAEONTOLOGY
Top Artists
impression of an
adult and juvenile
K kirtlingtonensis
in the Middle
Jurassic
ecosystem
Above Panciroli
searches for fossils
on the Skye
coastline
Digitally reconstructed CT images of adult and juvenile
K. kirtlingtonensis fossils, as discovered by Panciroli’s team on
Skye. The adult fossil was so deeply buried in rock that only
ESRF X-rays were able to provide clear imagery.
M A I J A K A R A L A N A T U R E 6 3 2 8 1 5 E. P A N C I R O L I