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2.2 Campanian burrows
The Campanian crustacean burrows into chalk filled with granular phosphorite were
described by Lewy & Goldring (2006). They comprise straight and slightly bent casts of
galleries covered by longitudinal scratches. Most of them were compressed by sediment
compaction but some preserve the circular cross-section of 14-17 mm in diameter. One of the
two kinds of chamber casts occurs in a constant size and a rounded shape 45 mm in
diameter. The biscuit-like chamber cast has a gently arched ceiling, with circular to ovoid
blister-like elevations covered by transversal fine ribs replicating scratches. The lower
surface of the cast comprises rings of about 8 tubercles 4 mm in diameter and 3.0-3.5 mm
high in a honeycomb pattern extending over the whole surface (Fig. 6 C, D). The tubercles
are smooth, but in an unfinished state of chamber the few tubercles bear fine scratches. On
opposite sides of the cast are relics of the pair of connecting galleries. This structure
construction replicates a pitted chamber-floor in which the honeycomb configuration of the
pits enables crustaceans to cross the chamber by stepping on the floor in the center of the pit
rings. This carefully constructed chamber floor comprises 60-70 pits which were interpreted
as individual sites for a large egg in a brood chamber within the network of the burrow
system. The other chamber type is represented by different shapes and dimensions
suggesting its continuous enlargement. The smallest chamber cast is flattened and biscuit-
like of a diameter of 4-5 cm, with both sides covered by the finely scratched blister-like
elevations. Further enlargement changes the round periphery into an arrowhead shape with
one end broad and rounded, tapering toward the opposite end (Fig. 6B). Above a length of
9-10 cm the enlargement of the chamber is vertical (Fig. 6A). The scratched elevations cover
the whole cast up to the longitudinally scratched gallery casts on both ends of the elongated
cast (Fig. 6B). Only movable objects could be stored in these gradually enlarged chambers.
Therefore they were interpreted as nursing chamber for the young, for storing food, and
perhaps also as gardening sites.
2.3 Comparison between the campanian and the lower eocene burrow systems
Both crustacean burrow systems were dug into pelagic chalk suggesting rather deep marine
bottom conditions of several hundred meters in depth. Both occur in the same region, which
at the time of deposition were on the seaward flank of the anticlinal structures of the Syrian
Arc fold system (Krenkel, 1924), which has been operating and intensifying the folded
structures from the Late Coniacian to the Middle Eocene. The chambers in both systems
posses the same wall structure carved by the crustacean appendages, and the similar
diameter of the galleries in both systems suggest morphological similarity of the producers.
The crustaceans living in the Campnian burrow system had to cross the chambers. Therefore
the brood chamber was carefully constructed to avoid damage to the eggs. The size of the
pits (D=4 mm) attests to the rather large size of the eggs hosted in the brood chamber,
probably being cared for until hatching. It seems that only the large eggs laid by the females
were kept to assure total recovery (K-type breeding) whereby the number of the young of
each hatching phase was the same, keeping more or less a constant size of the community.
The construction of the brood chamber, exclusively for egg development, required to
transfer the hatchling (larvae) to a nursery chamber where the young developed.
The Lower Eocene burrow system lacks the brood chamber and the single type of chamber
has a nearly constant flattened heart-like shape as if it was a concise shortened modification
of the Campanian nursery chamber. The entrance and exit at the opposite ends of the
Campanian nursery chamber, which required the crustaceans to cross the whole length of
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