During the Turonian, the Vallecillo plattenkalk would have been part of a relatively flat (i.e. low relief) open-ocean deep shelf, located about 500 kilometres (310 mi) offshore at the junction between the Western Interior Seaway and the prehistoric Gulf of Mexico.
Mauriciosaurus is thus the first juvenile polycotylid specimen known to have not been preserved in a shallow-water environment.
The oxygen-poor seafloor would have prevented carnivores, scavengers, or substrate-dwelling animals from feeding on the deposited carcasses, explaining the quality of preservation along with the absence of waves or currents.
In part, the anoxic conditions can be contributed to Oceanic Anoxic Event 2, which occurred at the Cenomanian-Turonian boundary.

Asides from Mauriciosaurus, a variety of invertebrates are also preserved in the Vallecillo plattenkalk.
By far the most abundant benthic invertebrates are inoceramid bivalves, which may have lived in symbiosis with chemoautotrophic microbes in order to survive in the low-oxygen conditions.

Three species of Mytiloides are associated with the ammonite Mammites nodosoides at Vallecillo, and may thus have lived alongside Mauriciosaurus - namely M. kossmati, M. goppelnensis, and possibly M. mytiloides.
Other ammonites that may have coincided with Mauriciosaurus included Pseudaspidoceras flexuosum, Watinoceras coloradoense, and a taxon referred to Vascoceras.
The sessile barnacle Stramentum, which grew on ammonite shells, is also known from Vallecillo, but it is impossible to determine what point in time they originated from.

Other vertebrates are also present throughout the Vallecillo plattenkalk, mostly consisting of fish.
Taxa that may have lived alongside Mauriciosaurus, from the Mammites nodosoides - Mytiloides kossmati biozone, include the holostean Nursallia cf.
gutturosum, the pachyrhizodontid Goulmimichthys roberti, the plethodid Tselfatia formosa, and the alepisauriform Rhynchodercetis sp.. Random surveys also revealed sharks, including Ptychodus mortoni and a lamniform; the enchodontoid Robertichthys riograndensis; the crossognathiform Araripichthys sp.;
and an indeterminate notacanthid.
Tetrapods are much rarer in the Vallecillo plattenkalk, consisting of the well-preserved back half of an aigialosaurid mosasaur bearing soft-tissue impressions, three turtles representing two taxa, and a tooth referred to the pliosaur "Polyptychodon".
However, "Polyptychodon" has more recently been considered a nomen dubium, with some of the teeth referred to the taxon being reclassified as those of polycotylids.
During the Turonian, the Vallecillo plattenkalk would have been part of a relatively flat (i.e. low relief) open-ocean deep shelf, located about 500 kilometres (310 mi) offshore at the junction between the Western Interior Seaway and the prehistoric Gulf of Mexico. Mauriciosaurus is thus the first juvenile polycotylid specimen known to have not been preserved in a shallow-water environment. The oxygen-poor seafloor would have prevented carnivores, scavengers, or substrate-dwelling animals from feeding on the deposited carcasses, explaining the quality of preservation along with the absence of waves or currents. In part, the anoxic conditions can be contributed to Oceanic Anoxic Event 2, which occurred at the Cenomanian-Turonian boundary.
Asides from Mauriciosaurus, a variety of invertebrates are also preserved in the Vallecillo plattenkalk. By far the most abundant benthic invertebrates are inoceramid bivalves, which may have lived in symbiosis with chemoautotrophic microbes in order to survive in the low-oxygen conditions.
Three species of Mytiloides are associated with the ammonite Mammites nodosoides at Vallecillo, and may thus have lived alongside Mauriciosaurus - namely M. kossmati, M. goppelnensis, and possibly M. mytiloides. Other ammonites that may have coincided with Mauriciosaurus included Pseudaspidoceras flexuosum, Watinoceras coloradoense, and a taxon referred to Vascoceras. The sessile barnacle Stramentum, which grew on ammonite shells, is also known from Vallecillo, but it is impossible to determine what point in time they originated from.
Other vertebrates are also present throughout the Vallecillo plattenkalk, mostly consisting of fish. Taxa that may have lived alongside Mauriciosaurus, from the Mammites nodosoides - Mytiloides kossmati biozone, include the holostean Nursallia cf. gutturosum, the pachyrhizodontid Goulmimichthys roberti, the plethodid Tselfatia formosa, and the alepisauriform Rhynchodercetis sp.. Random surveys also revealed sharks, including Ptychodus mortoni and a lamniform; the enchodontoid Robertichthys riograndensis; the crossognathiform Araripichthys sp.; and an indeterminate notacanthid. Tetrapods are much rarer in the Vallecillo plattenkalk, consisting of the well-preserved back half of an aigialosaurid mosasaur bearing soft-tissue impressions, three turtles representing two taxa, and a tooth referred to the pliosaur "Polyptychodon". However, "Polyptychodon" has more recently been considered a nomen dubium, with some of the teeth referred to the taxon being reclassified as those of polycotylids.
Mauriciosaurus