Mass Spectrometry and Antibody-Based Characterization of Blood Vessels from Brachylophosaurus canadensis

Structures
similar to blood vessels in location, morphology, flexibility,
and transparency have been recovered after demineralization of multiple
dinosaur cortical bone fragments from multiple specimens, some of
which are as old as 80 Ma. These structures were hypothesized to be
either endogenous to the bone (i.e., of vascular origin) or the result
of biofilm colonizing the empty osteonal network after degradation
of original organic components. Here, we test the hypothesis that
these structures are endogenous and thus retain proteins in common
with extant archosaur blood vessels that can be detected with high-resolution
mass spectrometry and confirmed by immunofluorescence. Two lines of
evidence support this hypothesis. First, peptide sequencing of Brachylophosaurus canadensis blood vessel extracts
is consistent with peptides comprising extant archosaurian blood vessels
and is not consistent with a bacterial, cellular slime mold, or fungal
origin. Second, proteins identified by mass spectrometry can be localized
to the tissues using antibodies specific to these proteins, validating
their identity. Data are available via ProteomeXchange with identifier
PXD001738.