Eolian Environments - Trace Fossils as Indicators of Sedimentary Environments - page 412

preserved as trace fossils. Phelps (2002) reported a rabbit trackway preserved
on the surface of one Pleistocene eolianite bed. Vertebrate burrows, however,
are locally common in the Pleistocene eolianites, often in direct association
with the arthropod burrows ( Fig. 2 C and D). They are highly branched, hori-
zontal tunnel systems that most likely were excavated by burrowing rodents,
but the exact taxa of rodents responsible for the burrows are undetermined at
this time. In terms of geometry alone, such burrows would be assigned to
Thalassinoides , but to avoid obvious confusion with the widespread crusta-
cean burrows that are universally recognized as Thalassinoides in marine
environments, we choose not to refer the Pleistocene rodent burrows to an
ichnogenus at this time.
FIGURE 2 Trace fossils in ancient coastal dunes. (A, B) Invertebrate (probably insect) burrows
preserved in Pleistocene eolianite near Puerto Pe˜asco, Sonora, Mexico. Horizontal meniscate burrow
( Taenidium ) and open shaft ( Skolithos ) in plan view (A, scale bar ¼ 15 cm) and horizontal semimenis-
cate burrow ( Entradichnus ) in plan view (B, scale bar ¼ 3 cm). (C, D) Vertebrate (probably rodent) bur-
row preserved in Pleistocene eolianite near Puerto Pe˜asco, Sonora, Mexico. Horizontal branching
burrow in plan view (C, scale bar ¼ 5 cm) and close-up view of same (D, scale bar ¼ 3cm).