Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), and new evolutionary insights into its gigantism, life history strategies, ecology, and extinction
Palaeontologia Electronica,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 1, 2025
Otodus
megalodon
(Lamniformes:
Otodontidae)
is
an
iconic
Neogene
shark,
but
the
lack
of
well-preserved
skeletons
has
hampered
our
understanding
various
aspects
its
biology.
Here,
we
reassess
some
biological
properties
using
a
new
approach,
based
on
known
vertebral
specimens
O.
and
165
species
extinct
extant
neoselachian
sharks
across
ten
orders.
Using
median
neurocranial
caudal
fin
proportions
relative
to
trunk
proportion
among
non-mitsukurinid/non-alopiid
lamniforms,
show
that
could
have
had
slender
body
possibly
reached
about
24.3
m
in
length.
Allometric
considerations
indicate
stout
plan
like
white
shark
(Carcharodon
carcharias)
for
incurred
excessive
hydrodynamic
costs,
further
supporting
interpretation
likely
slenderer
than
C.
carcharias.
A
24.3-m-long
may
weighed
around
94
t,
with
estimated
cruising
speed
2.1-3.5
km
h-1.
reanalysis
growth
bands
suggests
size
at
birth
3.6-3.9
megalodon,
previous
interpretations
ovoviviparity
embryos'
intrauterine
oophagous
behavior,
less
need
nursery
areas.
Additional
inferred
patterns
corroborated
by
fossil
record
support
hypothesis
emergence
carcharias
during
Early
Pliocene
least
partly
responsible
demise
due
competition
resources.
These
are
working
hypotheses
expected
serve
as
reasonable
reference
points
future
studies
biology
megalodon.
Язык: Английский
Cautionary tales on the use of proxies to estimate body size and form of extinct animals
Ecology and Evolution,
Год журнала:
2024,
Номер
14(9)
Опубликована: Сен. 1, 2024
Abstract
Body
size
is
of
fundamental
importance
to
our
understanding
extinct
organisms.
Physiology,
ecology
and
life
history
are
all
strongly
influenced
by
body
shape,
which
ultimately
determine
how
a
species
interacts
with
its
environment.
Reconstruction
form
in
animals
provides
insight
into
the
dynamics
underlying
community
composition
faunal
turnover
past
ecosystems
broad
macroevolutionary
trends.
Many
known
only
from
incomplete
remains,
necessitating
use
anatomical
proxies
reconstruct
form.
Numerous
limitations
affecting
appropriateness
these
often
overlooked,
leading
controversy
downstream
inaccuracies
studies
for
reconstructions
represent
key
input
data.
In
this
perspective,
we
discuss
four
prominent
case
(
Dunkleosteus
,
Helicoprion
Megalodon
Perucetus
)
proxy
taxa
have
been
used
estimate
shape
fragmentary
remains.
We
synthesise
results
other
nuances
validity
taxon
selection
when
reconstructing
organisms,
as
well
mitigation
measures
that
can
ensure
most
appropriate
proxy.
argue
precautionary
necessary
maximise
robustness
better
evolutionary
ecological
inferences.
Язык: Английский
Estimating body volumes and surface areas of animals from cross-sections
PeerJ,
Год журнала:
2024,
Номер
12, С. e17479 - e17479
Опубликована: Май 28, 2024
Background
Body
mass
and
surface
area
are
among
the
most
important
biological
properties,
but
such
information
is
lacking
for
some
extant
organisms
extinct
species.
Numerous
methods
have
been
developed
body
size
estimation
of
animals
this
reason.
There
two
main
categories
mass-estimating
approaches:
extant-scaling
approaches
volumetric-density
approaches.
Extant-scaling
determine
relationships
between
linear
skeletal
measurements
using
regression
equations.
Volumetric-density
approaches,
on
other
hand,
all
based
models.
The
models
various
types,
including
physical
models,
2D
images,
3D
virtual
reconstructions.
Once
constructed,
their
volumes
acquired
Archimedes’
Principle,
math
formulae,
or
software.
Then
densities
assigned
to
convert
masses.
acquisition
similar
volume
by
changing
formulae
software
commands.
This
article
presents
a
new
approach
called
cross-sectional
method
(CSM).
Methods
CSM
integrates
cross-sections
estimate
accurately.
It
requires
side
view
dorsal/ventral
image,
series
silhouettes
perform
calculation.
To
evaluate
performance
CSM,
(Graphic
Double
Integration
(GDI)
Paleomass)
compared
with
it.
Results
produces
very
accurate
results,
average
error
rates
around
0.20%
in
1.21%
respectively.
has
higher
accuracy
than
GDI
Paleomass
estimating
areas
irregular-shaped
structures.
Discussion
Most
previous
assume
an
elliptical
superelliptical
approximation
animal
cross-sections.
Such
does
not
always
good
performance.
processes
true
profiles
directly
rather
approximating
can
deal
any
shape.
process
objects
that
gradually
study
also
suggests
more
attention
should
be
paid
careful
otherwise
serious
errors
may
introduced
during
estimations.
Combined
modeling
techniques,
considered
as
alternative
under
certain
conditions.
reduce
complexity
making
reconstructions
while
ensuring
reliability
results.
Язык: Английский