PALAENTOLOGY

TRACE FOSSILS

1) Fugichnia : Escape structure

2) Repichnia : Crawling

3) Cubichnia : resting

4) Domichnia : Dwelling

5) Paschnia : Surface feeder

6) Fodinichinia : Feeding

DIFFERENT TERMS

1) Taphonomy: Study of organism from discovery to final death

2) Necrolysis : Breakup and decay of organism immediately after death

3) Biostratinomy : Study of processes operating after death to final burial

4) Diagenesis : Study of processes after final burial

CHARACTERISTIC FEATURES

• Lopophore : Brachiopods

• Water vascular system : Echinodermata

• Jet propulsion system : Cephalopods

• Torsion : Grastropoda

• Ecdysis and moulting : Trilobita

• Dentition pattern : Pelecypods

• Distinct suture lines : Cephalopods

• Siphuncle : Cephalopods

• Rhabdosome : Graptolites

• Neca, Secula : Graptolites

• Strepto spiral coiling : Foraminifera

• Theca, Epitheca : Corals

• Five ray pentameral symmetry : Echinoderamata

• Peristome, Periproct, Madreporite plate, Corals : Echinodermata

• Ectoderm, Endoderm : Cnidaris

• Mesenteries, Dissepiments : Corals

CORALS

• Corallite : Cup like or disk like skeletal structure

• Corallum : Complete exoskeleton of corals

• Apex : Tapering end of solitary corallum by which it is attached to substrate

• Calyx : Basal form of cup like depression on which polyp rests

• Mesenteries : A radial infolding of fleshy body wall

• Fossula : depression at the base of calyx

• Dissepiments : curved (Convex inward)

• Theca : Outer wall of exoskeleton of corallum and corallite

• Epitheca : layer of CaCO3 outside theca

• Tabulae : layer of horizontal sheets

• Columella: Rod like structure formed from swolen axial end of counter

BRACHIOPODA

• Exclusively marine and sessile

• Equilateral but inequivalved

• Triploblastic coelmate grade with oligomerous body plan

• Larger valve : Ventral or Pedicle valve

• Smaller valve : Dorsal or Brachial valve - Lopophore attaches to it

• Lopophore : Helps in gathering food and respiration, occur in pair with Cilia

MORPHOLOGY

• Mantle : all soft part enclosed within a thin skin called mantle , shell is chitinous or calcareous secreted by mantle

• Umbo : Posterior protuberanace , Beak : Pointed extreme point of umbo

• Auricles : Ear like projections

• Delthyrium : Triangular opening on ventral valve

• Notothyrium : Similar to delthyrium but located on dorsal side

• Deltidium : Delthyrium closed by means of two calcite plates

LIVING FOSSILS OF BRACHIOPODS

• Lingula

• Trimorella

• Discina

• Cranida

• Terrebratella

PELECYPODA

• Also known as Lamillibranchia nad Acephala

• Phyllum : Mollucs

• Inequivalved and inequilateral

TYPES

• Peristracum : outer layer - chitin

• Ostracum : middle layer - aragonite and calcite

• Hypostracum : Inner layer - alternate chitin and calcite

UMBO- Elevated and protruded part

• Prosogyre : beak pointing anteriorly (Arca,Venus)

• Opisthogyre : beak pointing posteriorly

• Orthogyre/Acline : beak pointing neutrally (Pecten)

TYPES OF DENTITION PATTERN

1) Homodont : Similar size and shaped teeth (Arca)

2) Heterodont : Different size and shaped teeth (Lucina, Glycimeris, Cerastoderma)

3) Taxodont : Numerous subparallel teeth with similar size (Arca, Nucula)

4) Dysodont : small teeth radiate from umbo (Mytillus)

5) Schizodont : Teeth appear to diverge from umbo (Unio, Trigonia)

6) Isodont : Teeth and sockets symmetrical on both valves (Spondyllus)

7) Desmodont : Mya, Ostrea, Gryphea, Exogyra

8) Pachydont : Hippurities

9) Pantodont : Allodesma

10) Anomalodont : Teeths and sockets are absent (Allorisma)

ECOLOGY

• Shallow burrower : Cyrena, Venus, Glycimeris

• Deep burrower : Mya, solen, ensis

• Borer and cavity dwellers: Teredo, Pholas

• Swimmer : Pecten, Lima

• Byssally attached : Mytillus

• Unattached recumbents : Gryphea

• Cemented: Ostrea

• Normal epifaunal benthic vagile : Arca, Cardita

EXTINCT FOSSILS OF PELECYPODA

• Inoceramus

• Gryphea

• Hippurities

TRILOBITA

• Bilateral symmetry

• Triplobalstic coelmate grade with metamerous body plan

• Phylum: Athropoda

• Shows metamorphosis

• Have most primitive visual systems

• Characteristic feature : Ecdysis and moulting

CLASSIFICATION

• Longitudinal : Pleural (on each side) and Axial lobes ( down the centre)

• Transverse : Cephalon, Thorax and Pygididium

MORPHOLOGY

• Cephalon : Anterior most part

• Glabella : Cephalic portion of the axial lobe

• Fixed cheeks (Fixigena) : Inner portion of each cheek fixed with glabella

• Free cheeks (Librigena) : Outer portion of cheek which is movable

• Hypostome : A plate on ventral side of cephalon in front of mouth

• Rostrum : A small shield like elevated portion in front of hypostome

FACIAL SUTURES

• Potoparian : Suture marginal to cephalon. eg: Olenellus

• Proparian : Suture originating from anterior and ending in front of genal angle

  eg: Dalmanites, Phacops

• Opisthoparian : Suture like proparian but ending posterior to the genal angle

  eg: Isotelus, Paradoxides

• Gonatoparian : Facial suture ending at genal angle , eg: Calymene

• Hypoparian : Marginal but on ventral side without eyes, eg: Paraherpes

PYGIDIUM

• Micropygous : Very small sized Pygidiyum, eg: Paradoxides

• Heteropygous : Large but smaller than Cephalon , eg: Calymene

• Isopygous : Pygidium and Cephalon are of equal size, eg: Isotelus

• Macropygous : Pygidium is larger than Cephalon, eg:Anisopyge

GASTROPODS

• Include snail and slugs

• Marine, Freshwater and terrestrial

• Characteristic feature : Torsion - Helps in rotation of Visecera

MORPHOLOGY

• Whorl : a complete revolution (360) of shell around the axis

• Whorl profile : whorl outline as appeared in the axial plane

• Spire : all whorl except the last one

• Body whorl : last whorl of the shell (usually the last one)

• Columella : pillar or rod like structure along the axis of coiling

COILING PATTERNS

• Sinistral : anticlockwise coiling, eg: Physa, Planorbis

• Dextral : Clockwise coiling, eg:voluta

• Planispiral : coiling around axis in a single plane

• Conispiral : coiling like a screw

• Evolute : loosely coiled, whorls not in contact eg: Ecculiompalus

• Advolute: whorls are just contact but not embracing , eg: Planorbis

• Involute : Natica

• Convolute : Cyphrea

CEPHALOPODS

• Exclusively marine

• Triplobalstic coelmate grade with amerous body plan

• Well known fossils

  • Ammonites : extinct in K/T boundary

  • Belemnites : extinct in K/T boundary

  • Nautilus : Triassic to recent

• Characteristic feature : Jet propulsion system

MORPHOLOGY

• Siphuncle : tube like structure and is connected by fleshy talk

• Jet propulsion : during swimming, a natuilus floods the mantle cavity with water, then closes off the entrances and forces the water out the nozzle like hyponome

COILING TYPES

• Planispiral : coiling around an axis in single plane, eg: Perisphincts

• Conispiral : coiling around an axis in different planes, eg: Turrilites

• Evolute : coiled shell but whorls are not touching, eg: Gyroceras

• Advolute: Coined shell, whorls just touching and all whorls visible, eg: Centroceras

• Involute: Coiled shell in which earlier whorls seen partly enveloped by

  later whorls. eg: Macrocephalites-

• Convolute: Coiled shell in which last whorl concealing the preceding whorls.

  eg: Nautilus

SUTURAL TYPES

• Orthoceratitic : Uncoiled, straight suture line , eg: Orthoceras

  

• Nautilitic : Undulating suture with both lobes and saddles are rounded, eg: Nautilus

  • Lobes : Rounded

  • Saddle : Rounded

  

• Goniatitic : Lobes are angular but saddles are rounded

  • Lobes : Angular

  • Saddles : Rounded

• Ceratitic : Lobes are crenulated but saddles are still rounded

  

• Ammonitic : Lobes are saddles are crenulated, complex structure

  

ECHINODERMATA

• Exclusively Marine

• Water vascular system

• Triploblastic Coelomate grade with oligomerous body plan

• Extinct fossils : Blastoids and Cystoids

• Characteristic feature : Five ray pentameral system

MORPHOLOGY

• Regularia : radial symmetry

• Irregularia : bilateral symmetry

• Peristome : a circular area enclosing mouth surrounded by soft plates

• Periproct : circular area enclosing anal aperture

• Corona : part of test excluding periproct, peristome and occutogenital ring

• Ambitus: peripheral outline of corona, that outline-shape of the test