  Recent measurements of charm-baryon production in proton-proton collisions at
the LHC have found a surprisingly large yield relative to those of $D$-mesons.
We propose that this observation can be explained by the statistical
hadronization model (SHM), by employing a largely augmented set of charm-baryon
states beyond the current listings of the particle data group. We estimate the
additional states using guidance from the relativistic quark model and from
lattice QCD. Using charm- and strange-quark fugacity factors to account for the
well-known suppression of heavy flavor in elementary collisions, we compute the
yields and spectra of $D$, $D_s$ and $\Lambda_c$ hadrons in proton-proton
collisions at $\sqrt{s}=5$\,TeV. Our main finding is that the enhanced feeddown
from excited charm baryons can account for the $\Lambda_c/D^0$ ratio measured
by ALICE at midrapidity, with some caveat for the forward-rapidity LHCb data.
Furthermore, assuming independent fragmentation of charm quarks but with the
hadronic ratios fixed by the SHM, the measured transverse-momentum ($p_T$)
spectra of $D$-mesons and $\Lambda_c$ can also be described; in particular, the
low-$p_T$ enhancement in the observed $\Lambda_c/D^0$ ratio is attributed to
the enhanced feeddown from "missing" charm-baryon states. We comment on the
implications of these findings for measurements of $D_s$ and $\Lambda_c$ in
heavy-ion collisions.
