Kind: captions
Language: en
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in the bluffs outside of Denver Colorado
paleontologist tyler lisa is searching
for evidence of a pivotal moment in our
evolution the rise of mammals after the
demise of the dinosaurs
the period right after the extinction of
the dinosaurs 66 million years ago is
one of the least understood moments in
time in all of Earth's history by Krell
Bluffs we find rocks of the right age so
we are looking for things like mammals
turtles crocodiles birds and plants and
trying to combine all that into the
reconstruction of the environment Tyler
an experienced dinosaur hunter was ready
to apply as fossil finding techniques to
the site the old search image sort of
classic paleontology where you go out
walk the bottom of a Ghale or the base
of a cliff and you'd find broken bits of
bone then you head up hill looking for
bigger bones weathering out of the dirt
or that Corral bluffs the search for
early mammals was coming up empty I
immediately start just searching for
bone and not finding anything so I was
pretty frustrated what could I do to
define fossils here the fossils were
there
Tyler was just looking for them in the
wrong way until he came across an old
specimen in the museum's vault it was a
mammoth skull embedded in a round rock
and that's when the light bulb went off
we're like I'm or maybe concretions
concretions are kind of like nodules
like an egg or a ball that you find in a
rock
James Hagedorn is curator of geology at
the Denver Museum of Nature and Science
he's a colleague of Tyler's and has lots
of experience with concretions so if you
have a skull or a tooth or even a bit of
poop and it falls to the seafloor or
ends up on the bottom of a lake and gets
buried it is compositionally different
than the rest of the sand around it or
the mud or whatever with typical fossils
the organic matter would slowly be
replaced by minerals leaving petrified
bones within the surrounding set
but with concretions the minerals encase
the organic matter as well creating a
distinctive rock within iraq the fossil
inside
that kaleidoscope of minerals getting
attracted to that tooth or skull or tree
root or something and they start to grow
around it layer by layer in the sediment
kind of like a pearl in an oyster the
mineral casing can preserve otherwise
fragile fossils just like those of the
early mammals
Tyler is looking for
the concretions form around these bones
and it creates this hard protective
shell and these fossils in their nice
protective casings roll down the hill
and then we crack them open
and sure enough exert fighting bone
inside
I just found a mammal skull and that was
a complete game-changer for this entire
project Tyler and the team split open
concretion after concretion revealing
hundreds of fossils including dozens of
mammals from the period right after the
dinosaurs went extinct
people have been looking for her fossils
in corral Bluffs for over a hundred
years and they just didn't look for
concretions if they were looking for
actual leaves or they were looking for
bones it was an honest mistake
the concretions here are formed by a
mineral called apatite which is not
usually associated with terrestrial
sites like the devil mason apatite is
the same mineral that my teeth and bones
and are made out of in so are yours
in marine settings in ancient oceanic
deposits they're pretty common
prior to working on this project I had
never seen an appetite concretion in a
terrestrial setting it's super rare
yet here in plain sight apatite
concretions have been hiding priceless
specimens from one of the most important
periods in the mammal evolution
Tyler has a paleontological goldmine
right there
I mean there's just nothing like it
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would it be cool if you could find more
of them because nature repeats itself
whatever processes led to the formation
of those fossils and the preservation of
them ought to repeat itself elsewhere in
the world
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