  We find that singlet superconducting pairing can lead to Majorana fermions in
three dimensional Dirac superconductors (3DDS) if the pairing order parameter
is a pseudo-scalar, i.e. it changes sign under mirror reflection. The
pseudo-scalar superconducting order parameter, $\Delta_5$ can close and reopen
the spectral gap caused by the scalar Dirac mass $m$ in a three-dimensional
Dirac material (3DDM), giving rise to a two-dimensional Majorana sea (2DMS) at
the plane of the gap kink. By bringing the Hamiltonian into a canonical form
which then gives the winding number, we show that this system belongs to the
DIII class of topological superconductors. We calculate the transport signature
of 2DMS, namely a perfect Andreev-Klein transmission that manifests in a robust
peak in the differential conductance. Further, we find the $4\pi$ periodicity
in the $\Delta_5|m|\Delta_5$ Josephson junc- tions. Gauge transformed version
of the present scenario implies that the interface of a conventional s-wave
superconductor with a peculiar 3DDM whose mass is a pseudo-scalar, m5 also
hosts a 2DMS.
