1. 4th International Symposium Coleoid Cephalopods Through Time, Stuttgart, September 2011
Pro-ostraca and Pro-ostracum-like Structure of Triassic Coleoids (Belemnoidea: Phragmoteuthida, Aulacocerida)
Larisa A. Doguzhaeva and Herbert Summesberger
Swedish Museum of Natural History, Stockholm
Museum of Natural History, Vienna, Austria

2. Methods of study: (1)SEM and (2)EDS
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart 2
The aim of the study: Morphology and ultra-structure of pro-ostracum at the Triassic stage of coleoid evolution.
ventral view
lateral view
Methods of study: (1)SEM and (2)EDS
analyses of pro-ostracum, conotheca, septa and soft tissue remains, and (3)Comparative and (4)Evolutionary morphology.
dorsal view
Ventral, lateral and dorsal external aspects
of phragmocone (by
Phillips, 1865; modified).
pro-
ostracum
logical discordance
muscular
mantle
ventral
surface
A – longitudinal view,
B – ventral view,
C – dorsal view,
D, E – shell wall ultrastructures.
dorsal
surface
Reconstruction of pro-ostracum on the basis of Jurassic belemnite Megateuthis and Cretaceous belemnite Conobelus.

3. Historical background3
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
Historical background
From the classical viewpoint (Naef, 1922; Jeletzky, 1966), the Late Triassic Phragmoteuthis Mojsisovics, is of special phylogenetic value, as it had been considered as the earliest cephalopod possessing an internal shell, and as the intermediate form between the Bactritoidea (shell is external) and Teuthoidea (shell is a dorsal chitinous elongated transparent plate, or gladius).
pro-ostracum
Phragmoteuthis bisinuata (Bronn)
(Coll. Mus. Nat. Hist., Vienna)

4. (Coll. Mus. Nat. Hist., Vienna)4
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The pro-ostracum associated with the phragmocone remains in Phragmoteuthis bisinuata (Bronn)
pro-ostracum
pro-ostracum
chambers
phragmocone
Median and left fields of the
pro-ostracum associated with partially preserved phragmocone.
Median and right fields
of the pro-ostracum preserved.
Long portion of the fractured
phragmocone preserved
(Coll. Mus. Nat. Hist., Vienna)

5. (Coll. Mus. Nat. Hist., Vienna)5
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The pro-ostracum associated with the arm hooks, ink sac and mantle remnants in Phragmoteuthis sp.
arm hooks
mantle remnants
ink sac
(Coll. Mus. Nat. Hist., Vienna)

6. (Coll. Mus. Nat. Hist., Vienna)6
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The pro-ostracum coated with soft tissue remnants in Phragmoteuthis sp.
The Phragmoteuthis from the N. Alps has been found together with the arm-hooks (Suess, 1865; Mojsisovics, 1882). It is therefore reasonable to expect that remnants of soft tissues in this coleoid might be preserved together with their shells. The SEM and EDS study on the black material confirmed this idea (Doguzhaeva et al., 2007).
The specimen with black material above the pro-ostracum
The black sheet consists of irregularly shaped aggregates
of smaller particles
(Coll. Mus. Nat. Hist., Vienna)

7. 7
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The tripartite pro-ostracum only recorded in the Middle Triassic Breviconoteuthis and the Late Triassic Phragmoteuthis (Order Phragmoteuthida)
1. Breviconoteuthis
breviconus (Reis)
2-4. Phragmoteuthis bisinuata (Bronn) 2 3 4
1cm
1 cm
1 cm
Sp. NHMW
2005z0005/103
Sp. NHMW
2005z0005/32
Sp. NHMW
2005z0005/31
(Coll. Mus. Nat. Hist.,Vienna)
(after Reiber, 1974)

8. the pro-ostracum-like8
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The pro-ostracum-like structure of the Late Triassic Austroteuthis kuehni (Order Aulacocerida)
The Triassic genus Austro-teuthis is a solo known aulacocerid preserving a pro-ostracum-like structure
Schematic drawing of
the pro-ostracum-like
structure‏
Pro-ostracum-like structure
of the Late Carboniferous Donovaniconus oklahomensis
growth
lines
Pro-ostracum-
like structure
is indicated
with curved
forwardly
growth lines
on dorsal
side
(from Doguzhaeva et al.,
2010)
Dorsal side of phragmocone marked with unpaired dorsal scars (Doguzhaeva et al, 2003)
phragmocone
rostrum
(from Jeletzky and Zapfe, 1967: Pl. I, modified)‏

9. 9
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart
The pro-ostracum of the Late Triassic Lunzoteuthis Doguzhaeva, Summesberger et Mutvei, 2006
Small compressed shell preserved together
with a mandible and showing a pro-ostracum.
The pro-ostracum shows a central
field with rounded growth lines and
the lateral fields with longitudinal ribs.
1 mm
ribbed
lateral field
Sp. NHMW 2005z0005/0001 (holotype; Coll.
Mus. Nat. Hist.,Vienna)

10. 4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart10
The pro-ostracum and jaw ultrastructures of Lunzoteuthis as an indicator of an organic-rich composition of the former
The pro-ostracum ultrastructure
The jaw ultrastructure
(Doguzhaeva, Summesberger and Mutvei, 2006)

11. The pro-ostracum ultrastructure in Phragmoteuthis
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart 11
The pro-ostracum ultrastructure in Phragmoteuthis
Splitting as an indicator of laminated structure, and typical poly-gonal pattern of cracks of the pro-ostracum
Nacreous layer of conotheca
Lamello-columnar u-structure of the inner layer
Plate ultrastructure of the outer layer
(Doguzhaeva, Summesberger, Mutvei and Brandstaetter, 2007)

12. 4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart12
The ultrastructure of pro-ostracum in Early Jurassic Belemnotheutis Pearce
20 um
Lamination, criss-cross pattern and double-layer structure of pro-ostracum.
Longitudinal striation
of lateral field.
Conotheca
rostrum
Pro-ostracum. Vertical elements with regular horizontal incisions.
Micro-
laminae of
columnar
units.
rostrum
pro-ostracum
conotheca
Columnar units
of pro-ostracum.
(Doguzhaeva, Donovan and Mutvei, 2006)

13. Morphology and ultrastructure of pro-ostracum in Jurassic Megateuthis
4th International Symposium Coleoid Cephalopods Through Time /September 2011, Stuttgart 13
Morphology and ultrastructure of pro-ostracum in Jurassic Megateuthis mf hz
Impression of the
outer surface of
pro-ostracum and
muscular tunic
with intersecting fibres (f) f
Median (mf)
and lateral (hz) fields of pro-ostracum
Complicated u-structure of the pro-ostracum remarkably different from that of conotheca
Lateral field, with longitudinal, flat-topped ridges
Different orientation of
crystallites in adjacent
lamellae on inner surface. pf hz t
Multi-lamellar pro-ostracum (pro) external to the nacreous layer. f
Rostrum (r ), predominantly
organic pro-ostracum (pro),
nacreous (nac) and inner
prismatic (pr) layers of the
conotheca,
Collagen fibres
(f) intersecting at ca. 30° and nearly parallel fibres (pf) at the top
(Doguzhaeva , Mutvei and Donovan, 2002)

14. mural rings of last septa14
4th International Symposium Coleoid Cephalopods Through Time, Stuttgart, September 2011
For a question on origin of pro-ostracum: The Early Carboniferous Hematites Flower et Gordon (Order Hematitida) has neither body chamber nor pro-ostracum. A
Ventro-lateral view
Lateral view
septum B
siphuncle
Ventral view
siphuncle
septum
Lateral apertural sinus
Ventral apertural sinus
Hematites.
Rostrum
showing ‘cut’ marks of longitudinal ridges
(A,surface view; B, cross section)
mural rings of last septa
Ventral apertural sinus
(Doguzhaeva, Mapes and Mutvei, 2002)

15. 4th International Symposium Coleoid Cephalopods Through Time, Stuttgart, September 201115
Is a pro-ostracum a remnant of the body chamber wall or a novelty in cephalopod evolution ?
I. If a pro-ostracum were a remnant of the body chamber wall, it would had similar ultrastructure to that of
the conotheca. - It didn’t.
II. If a pro-ostracum were an
ultrastructurally modified remnant of body chamber
wall, the latter would be
missing on dorsal side. - It isn’t.
III. If a pro-ostracum were a homologous structure of the periostracum, it would have similar structure to that of the latter. – It hasn’t.
IV. It has been recently revealed that in Phragmoteuthis, Lunzoteuthis, Nannobelus, Megateuthis and Belemnotheutis the pro-ostracum represents a laminated formation that has a specific partly organic, loosely mineralized ultrastructure unknown in any other skeleton element.
Therefore, the pro-ostracum is considered to be a novelty in belemnoid branch of coleoid evolution rather then a remnant of the conotheca.
pro-ostracum
rostrum
septum
conotheca

16. 16
4th International Symposium Coleoid Cephalopods Through Time, Stuttgart, September 2011
Conclusions: Among Triassic coleoids there were forms developed (1) a pro-ostracum-like structure (aulacocerid genus Austroteuthis), (2) a tripartite pro- ostracum lacking lateral ribbed zones (phragmoteuthids Breviconoteuthis breviconus (Reis), Phragmoteuthis bisinuata (Bronn)), and (3) a pro-ostracum with a ribbed lateral zones (Lunzoteuthis schindelbergensis) In spite of different morphology, the pro-ostraca of Lunzoteuthis and Phragmoteuthis are similar in a respect of their ultrastructure. They are made neither of prismatic, nor nacreous layers which are typical for the shell wall. The pro-ostraca consist of two layers showing micro-laminated ultrastructure. Therefore, a pro- ostracum is considered as a novelty rather then as a dorsal projection of the shell wall Lunzoteuthis type of pro-ostracum, because of its ribbed lateral fields, possibly provided an advantage in articulation of pro-ostracum and mantle and, on account of this, was further developed in Early Jurassic belemnites (Doguzhaeva, in press).

17. Herbert Summesberger and Larisa Doguzhaeva
Dear organizers and participants of the
4th International Symposium Coleoid Cephalopods Through Time,
Stuttgart, 2011,
Thank you so much for your attention !
Herbert Summesberger
and Larisa Doguzhaeva