PHOTO: ROBERT DEPALMA
SCIENCE science.org 29 OCTOBER 2021 • VOL 374 ISSUE 6567 521W
hen a massive asteroid struck
Earth some 66 million years ago,
were dinosaurs around to expe-
rience the cataclysm? Two years
ago, a paleontologist claimed to
have found evidence at a fossil-
rich North Dakota site called Tanis that di-
nosaurs were alive until moments after the
impact, when floodwaters surged over them.
But many paleontologists were skeptical, es-
pecially because the dinosaur data were first
discussed in a magazine story rather than a
peer-reviewed journal.
Last week, at the annual meeting of the
Geological Society of America in Portland,
Oregon, paleontologist Robert DePalma
and colleagues added detail to their claims.
They presented evidence of fossils from
Tanis—including stunningly well preserved
bones, skin, and footprints from what’s prob-
ably a Triceratops—that suggest dinosaurs
were indeed witnesses to the asteroid that
ushered them out of existence.
“This is a good example that shows a
healthy ecosystem in the Dinosauria priorto the extinction,” says Sean Gulick, a geo-
physicist at the University of Texas, Austin,
who attended the talk.
Many scientists agree the dinosaurs
lived until the asteroid impact, but some
paleontologists are reserving judgement
on the new data from Tanis. The meeting
presentation is “a step in the right direc-
tion,” says Kay Behrensmeyer, a vertebrate
paleontologist at the Smithsonian Institu-
tion’s National Museum of Natural History.
But although the claims “are dramatic and
compelling, especially to nonpaleontologists,”
she says the team hasn’t fully considered al-
ternative interpretations that might compli-
cate dating of the fossils.
The fateful asteroid that struck what
is today Mexico’s Yucatán Peninsula near
the town of Chicxulub Pueblo left a crater
150 kilometers in diameter. It sent violent
shock waves across the globe, kicked up
plumes of hot dust and ash, and triggered
volcanic eruptions and roiling tsunamis. The
apocalyptic spectacle marked the end of the
Cretaceous period, during which dinosaurs
had dominated the landscape, and the start
of the Paleogene era.Carnegie Institution for Science, won’t go
that far, but he thinks Hirsch’s concerns
about AC susceptibility measurements are
fair. “I tend to believe there is a problem
with the [CSH] paper,” says Goncharov, who
tried repeatedly to synthesize CSH using
Dias’s recipe and failed.
Given the questions, several scientists say
Dias should make his data public. “I am un-
happy that Dias is supposedly not cooper-
ating with researchers who are questioning
his data,” says Marvin Cohen, a theoretical
physicist at UC Berkeley. Schilling is blunt:
“I told Dias to give [Hirsch] the raw data,
for heaven’s sake.”
Dias and others say they don’t trust Hirsch
to appraise the data fairly. “Unfortunately,
sometimes he is not objective,” says Vasily
Minkov, a chemist at the Max Planck In-
stitute for Chemistry who synthesizes hy-
dride superconductors and says Hirsch has
cherry-picked data from the Max Planck ex-
periments for his critiques. Hirsch calls such
critiques “completely unfounded.” He says his
belief that the BCS theory is incorrect “does
not mean I am ‘biased’ or not ‘impartial.’ It
means that I am motivated to scrutinize care-
fully the experimental evidence and judge it
on its merits, as opposed to assuming it is
likely to be right because BCS theory predicts
it to be right, as everybody else does.”
Several new results have only deepened
the mystery. In a preprint posted on 30 Sep-
tember on arXiv, Goncharov’s group reports
synthesizing CSH under high pressure—
using a recipe different from Dias’s—and ob-
serving a crystalline structure similar to the
one Dias reported. Goncharov’s team didn’t
test whether its CSH sample was super-
conducting. But in unpublished work,
Minkov says he and his colleagues synthe-
sized the same CSH structure as Dias’s and
found it doesn’t superconduct above the Tc
of H 3 S. Minkov says H 3 S may be responsible
for superconductivity in his CSH sample. “We
couldn’t see any effect of carbon,” he says.
Hirsch, meanwhile, is mounting a broader
attack: on claims for superconductivity in
any hydride. In a preprint posted on 4 Octo-
ber on Research Square, Minkov and a team
led by Mikhail Eremets, a physicist also at
Max Planck, reported remaking diamond
anvil cells without magnetic materials and
testing large samples of two hydrides, H 3 S
and LaH 10. The result: the first ever evidence
of the Meissner effect in hydrides, which
the team calls “unambiguous evidence”
that superconductivity in hydrides is real.
Hirsch disagrees, calling the analysis “deeply
flawed” in a preprint he and a colleague
posted on 14 October on the arXiv server.
Only one thing seems certain to emerge
from the controversy over room-temperature
superconductivity: more heat. jPALEONTOLOGYBy Michael PriceDinosaurs thrived until asteroid
hit, new fossils suggest
Data from Tanis site—claimed to preserve the Cretaceous
extinction—impress some geologists, but skeptics remain
Robert DePalma (left) and a colleague study a dinosaur footprint, likely from a theropod, at North Dakota’s Tanis site.