Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur
Fossil Studies,
Год журнала:
2024,
Номер
2(1), С. 1 - 65
Опубликована: Янв. 3, 2024
Tyrannosaurs
are
among
the
most
intensively
studied
and
best-known
dinosaurs.
Despite
this,
their
relationships
systematics
highly
controversial.
An
ongoing
debate
concerns
validity
of
Nanotyrannus
lancensis,
interpreted
either
as
a
distinct
genus
small-bodied
tyrannosaur
or
juvenile
Tyrannosaurus
rex.
We
examine
multiple
lines
evidence
show
that
strongly
supports
recognition
species
for
following
reasons:
1.
High
diversity
tyrannosaurs
predatory
dinosaurs
idea
tyrannosaurids
inhabited
late
Maastrichtian
Laramidia;
2.
lacks
characters
supporting
referral
to
Tyrannosaurinae
but
differs
from
T.
rex
in
>150
morphological
characters,
while
intermediate
forms
combining
features
unknown;
3.
Histology
shows
specimens
showing
(i)
skeletal
fusions,
(ii)
mature
skull
bone
textures,
(iii)
slow
growth
rates
relative
rex,
(iv)
decelerating
final
years
life,
(v)
curves
predicting
adult
masses
~1500
kg
less,
these
animals
subadults
young
adults,
not
Tyrannosaurus;
4.
series
other
tyrannosaurids,
including
Tarbosaurus
Gorgosaurus,
do
changes
proposed
Nanotyrannus–Tyrannosaurus
series,
deriving
requires
several
inconsistent
with
known
patterns
dinosaur
development;
5.
Juvenile
exist,
diagnostic
6.
Phylogenetic
analysis
suggests
may
lie
outside
Tyrannosauridae.
Tyrannosaur
before
K-Pg
extinction
is
higher
than
previously
appreciated.
The
challenges
inherent
diagnosing
based
on
fossils
mean
paleontologists
be
systematically
underestimating
ancient
ecosystems.
Язык: Английский
A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs
Fossil Studies,
Год журнала:
2024,
Номер
2(4), С. 245 - 272
Опубликована: Сен. 25, 2024
The
end
of
the
Cretaceous
saw
Western
Interior
Seaway
divide
North
America
into
two
land
masses,
Laramidia
in
west
and
Appalachia
east.
Laramidian
dinosaurs
inhabited
a
narrow
strip
extending
from
Mexico
to
Alaska.
Within
this
geographically
restricted
area,
evolved
high
diversity
endemism,
with
distinct
species
north
south.
Here,
we
report
new
tyrannosaurid
Late
Campanian-aged
Cerro
del
Pueblo
Formation
Coahuila,
Mexico,
which
is
part
tribe
tyrannosaurs
originating
southern
Laramidia.
Phylogenetic
analysis
recovers
tyrannosaur
as
clade
including
Labocania
anomala
La
Bocana
Roja
Baja
California
Norte,
Bistahieversor
sealeyi
Kirtland
New
Teratophoneus
curriei
Kaiparowits
Utah,
Dynamoterror
dynastes
Menefee
Mexico.
Distinct
frontal
morphology
younger
age
(~72.5–73
Ma
versus
>75.8
for
L.
anomala)
support
recognition
Labocania,
aguillonae.
dominated
at
time
when
was
by
daspletosaurins
albertosaurines.
endemism
seen
tyrannosaurids
remarkable,
given
that
modern
apex
predators
have
large
geographic
ranges
hints
carnivorous
has
been
underestimated.
Язык: Английский
Reanalysis of a dataset refutes claims of anagenesis within Tyrannosaurus-line tyrannosaurines (Theropoda, Tyrannosauridae)
Cretaceous Research,
Год журнала:
2023,
Номер
155, С. 105780 - 105780
Опубликована: Ноя. 28, 2023
The
recently
described
tyrannosaurine
(Theropoda,
Tyrannosauridae)
species
Daspletosaurus
wilsoni
was
suggested
to
show
evidence
for
anagenesis
within
the
genus
and
derived
Tyrannosaurinae.
Here,
we
evaluate
methodology
conclusions
made
by
authors.
Reanalysis
of
their
dataset
with
additions
consistently
applied
methodologies,
shows
that
there
is
no
strong
a
single
anagenetic
lineage
'Tyrannosaurus-line'
tyrannosaurines
throughout
latest
Cretaceous.
Our
study
demonstrates
cladogenetic
Tyrannosaurinae
composed
four
morphologically
biogeographically
distinct
clades.
Two
these
clades
are
formally
defined
diagnosed
herein
(Teratophoneini
clade
nov.
Tyrannosaurini).
Teratophoneini
currently
restricted
southern
latitudes
Campanian
Laramidia,
while
Tyrannosaurini
present
in
both
Maastrichtian
strata
Asia
Laramidia.
Inclusion
unnamed
from
Dinosaur
Park
Oldman
formations
reveals
not
found
be
driver
speciation
Daspletosaurus.
We
also
demonstrate
all
known
do
meet
previously
established
prerequisites
advise
against
prematurity
when
making
concerning
significant
processes
surrounding
mode
evolution
extinct
genera
sparse
often
incomplete
fossil
records.
Future
detailed
anatomical
description
specimens
representing
proposed
fourth
will
further
aid
elucidating
this
more
generally.
Язык: Английский
A reappraisal of tyrannosauroid fossils from the Iren Dabasu Formation (Coniacian–Campanian), Inner Mongolia, People’s Republic of China
Journal of Vertebrate Paleontology,
Год журнала:
2022,
Номер
42(5)
Опубликована: Ноя. 25, 2022
The
hind
limb
of
the
lectotype
Alectrosaurus
olseni
is
described
in
comparison
with
other
tyrannosauroids.
In
addition
to
autapomorphies
for
by
previous
workers,
taxon
possesses
a
specialized
pes,
where
distal
condyles
metatarsals
and
most
phalanges
are
strongly
elevated
beyond
dorsal
ventral
surfaces
shaft
each
bone,
here
as
'pediculate'
condition.
lectotype,
previously
reported
Tyrannosaurus
bataar
material
from
Turonian
Uzbekistan,
fossils
Kyzylkum
Desert,
not
referable
Alectrosaurus.
A
partial
skull
Iren
Dabasu
Formation
A.
because
lack
shared
diagnostic
bones
between
it
lectotype.
Several
features
skull,
holotype
Raptorex,
an
isolated
juvenile
T.
rex
lacrimal,
exclusion
derived
Язык: Английский
Resolving the "Ontogeny Problem" in Vertebrate Paleontology
bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2024,
Номер
unknown
Опубликована: Окт. 28, 2024
Abstract
Ontogenetic
change
is
a
major
source
of
phenotypic
variation
among
members
species
and
often
greater
magnitude
than
the
anatomical
differences
that
distinguish
closely
related
species.
Ontogeny
has
therefore
become
problematic
confounding
variable
in
vertebrate
paleontology,
especially
study
systems
distant
from
extant
crown
clades,
rendering
taxonomic
hypothesis
testing
(a
fundamental
process
evolutionary
biology)
rife
with
difficulty.
Paleontologists
have
adopted
quantitative
methods
to
compensate
for
perception
juvenile
specimens
lack
diagnostic
apomorphies
seen
their
adult
conspecifics.
Here,
I
critically
evaluate
these
assumptions
guide
interpretation
using
µCT
dataset
comprising
growth
series
American
Chinese
alligator.
find
several
widespread
are
scientifically
unjustifiable,
two
popular
–
geometric
morphometrics
cladistic
analysis
ontogeny
unacceptably
high
rates
type
II
error
present
numerous
procedural
difficulties.
However,
also
identify
suite
ontogenetically
invariant
characters
differentiate
living
Alligator
throughout
ontogeny.
These
overwhelmingly
correspond
develop
prior
(and
play
signaling
role
in)
development
cranial
skeleton
itself,
suggesting
ontogenetic
invariance
consequence
widely
conserved
developmental
program.
observations
suggest
architecture
cranium
fixed
early
embryonic
development,
remodeling
does
not
alter
topological
relationships
bones
or
soft
tissue
structures
they
house.
propose
general
model
future
tests
fossil
record,
which
different
stages
single
can
be
falsified
by
discovery
character
cannot
attributed
plausibly
variation.
Язык: Английский
Taxonomic status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea) — a distinct taxon of small-bodied tyrannosaur
Опубликована: Окт. 23, 2023
Abstract:
Tyrannosaurs,
giant
predatory
dinosaurs
from
the
end
of
Cretaceous,
are
among
most
intensively
researched
and
best-known
groups
dinosaurs.
Despite
this,
their
relationships
systematics
highly
controversial,
number
tyrannosaur
species
occurring
in
latest
Cretaceous
North
America
is
debated.
An
ongoing
debate
concerns
status
Nanotyrannus
lancensis,
which
has
variously
been
interpreted
as
a
distinct
taxon
small-bodied
or
juvenile
coeval
Tyrannosaurus
rex.
Here,
we
review
multiple
lines
evidence
show
that
totality
strongly
supports
recognition
species:
1.
The
high
diversity
Late
tyrannosaurs
general
consistent
with
idea
more
than
one
lived
late
Maastrichtian
Western
America;
2.
shows
few
if
any
diagnostic
characters
allowing
referral
specifically
to
even
Tyrannosaurinae,
but
differentiated
T.
rex
by
at
least
77
morphological
characters,
while
intermediate
forms,
combining
characteristics
rex,
remain
unknown;
3.
Histological
individuals
previously
referred
lancensis
(i)
skeletal
fusions
maturity,
(ii)
skull
bone
textures
(iii)
slow
growth
rates
relative
(iv)
decelerating
final
years
life,
(v)
curves
predicting
adult
body
sizes
~1500
kg
less,
implying
these
animals
young
adults,
not
juveniles
Tyrannosaurus;
4.
Juveniles
other
tyrannosaurids,
including
Gorgosaurus
Tarbosaurus,
do
kinds
changes
proposed
for
Nanotyrannus-Tyrannosaurus
series,
suggesting
morphology
cannot
simply
be
explained
result
immaturity;
5.
Small
exist,
comparable
size
Nanotyrannus,
exhibit
features
Tyrannosaurus,
differ
Nanotyrannus;
6.
Phylogenetic
analysis
suggests
tyrannosaurid.
Taken
together,
rejects
tentatively
placement
outside
Tyrannosauridae
non-tyrannosaurid
member
Tyrannosauroidea.
Tyrannosaur
appears
have
higher
appreciated
before
K-Pg
extinction.
difficulties
recognizing
based
on
fossils
alone
mean
paleontologists
may
systematically
biased
towards
underestimating
ancient
ecosystems.
Язык: Английский
Observations on Paleospecies Determination, With Additional Data on Tyrannosaurus Including Its Highly Divergent Species Specific Supraorbital Display Ornaments That Give T. rex a New and Unique Life Appearance
bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2022,
Номер
unknown
Опубликована: Авг. 5, 2022
Abstract
Intrageneric
dinosaur
species
have
been
being
named
for
decades
without
either
significant
examination
of
the
methods
and
standards
used
to
do
so,
or
widely
publicized
controversy
over
results.
The
long
standing
assumption
that
all
large
known
specimens
iconic
North
American
Tyrannosaurus
consisted
just
one
popular
T.
rex
was
recently
challenged
with
first
comprehensive
test
question.
result
diagnosing
naming
two
additional
taxa,
imperator
regina,
based
on
a
number
levels
characters
regarding
robustness
tooth
proportions
in
context
their
stratigraphic
distribution.
In
association
rare
in-depth
look
taken
at
current
state
vertebrate
paleospecies,
which
it
turns
out
are
not
highly
rigorous
because
inherent
problems
concept
other
matters.
results
paper
were
severely
criticized
manner
never
seen
before
new
even
when
less
evidence.
This
study
takes
another
as
determination
shows
many
claims
made
criticisms
work
inaccurate.
New
data
strength
bars
skulls
reinforces
basing
three
part
factors,
allows
but
skull
be
assigned
species.
These
allow
detailed
systematic
supraorbital
display
bosses
genus.
They
sort
visually
distinctive
specific
ornaments
both
taxonomic
strongly
affirm
multispecific,
probably
dimorphic.
show
sported
–
males
--
striking
yet
observed
tyrannosaurids.
Язык: Английский
Comparisons of specimens attributed to Tyrannosaurus: One or three species ?
Research Square (Research Square),
Год журнала:
2022,
Номер
unknown
Опубликована: Сен. 22, 2022
Abstract
Tyrannosaurus
was
a
massive
carnivorous
dinosaur
which
existed
for
roughly
2
million
years
in
North
America
prior
to
its
extinction
at
the
end
of
Cretaceous
Period.
It
recently
proposed
by
Gregory
Paul
and
colleagues
that
fossil
specimens
historically
attributed
species
T.
rex
represent
three
species,
not
one.
This
conclusion
reflects
an
essential
problem
palaeontology
defining
recognizing
boundaries.
In
this
study
we
test
T1
hypothesis
imperator
,
regina
single
(recognising
that,
per
International
Code
Zoological
Nomenclature
nomen
(1905)
has
precedence
over
).
Based
on
analysis
skull
postcranial
dimensions
iconic
application
probabilistic
morphometric
definition
as
described
Thackeray
&
Dykes,
our
results
indicate
high
probability
conspecificity,
thus
supporting
hypothesis.
Язык: Английский