Early Fish Geological Time Scale

MD. ABU HORAYRA
B.Sc (Hons),Zoology.
NATURE EYE CO-ORDINATOR
JAGANNATH UNIVERSITY
DHAKA,BANGLADESH
HELP FROM WIKI

 Fish & Early fish:
1. A limbless cold-blooded vertebrate animal with gills
and fins and living wholly in water.
2. Early fish from the fossil record are represented by
a group of small, jawless, armoured fish known as
ostracoderms. Jawless fish lineages are mostly
extinct. An extant clade, the lampreys may
approximate ancient pre-jawed fish.
WHAT IS FISH AND EARLY
FISH?

 The earth past history is divided into six eras:
1.Azoic
2.Archaeozoic or Eozoic
3.Proterozoic(Early life)
4.Palaeozoic(Ancient life,First fish in this era at
Ordovician periods,230-505 m.y.
ago)
5.Mesozoic (Mediaeval life,135-205 m.y. ago)
6.Cenozoic (Recent life,0.025-75 m.y. ago)
GEOLOGICAL TIME SCALE

 Paleozoic era divided into 7 periods:
1.Cambrium (505 m.y. ago, 80 m.y. duration,Trilobites
present, No fish in this period)
2.Ordovician (425 m.y. ago, 65 m.y. duration, First fish
found, probably freshwater, e.g.
Arandaspis)
3.Silurian (360 m.y. ago, 35 m.y. duration, Marine
arachnids dominant, rise of fish,e.g. spiny
shrak)
DISCUSS ABOUT PALAEOZOIC
ERA ON THE BASIS OF EARLY
FISH

4.Devonian (325 m.y. ago, 45 m.y. duration, Lung
fishes, Sharks abundant)
5.Mississippian/Carboniferous (280 m.y. ago, 25
m.y.
duration, spread of ancient shark)
6.Pennsylvanian/Carboniferous (255 m.y. ago, 25
m.y.
duration, first reptiles )
7.Permian(230m.y. ago,25 m.y. duration,many
ancient
animals died out)
DISCUSS ABOUT PALAEOZOIC
ERA ON THE BASIS OF EARLY
FISH

EARLY FISH ACCORDING TO GEOLOGICAL
TIME SCALE…
 Paleozoic era
1.Cambrian period:
a)Pikaia
Pikaia, along with Myllokunmingia and
Haikouichthys ercaicunensis immediately below, are all
candidates in the fossil record for the titles of "first
vertebrate" and "first fish". Pikaia is a genus that appeared
about 530 Ma during the Cambrian explosion of
multicellular life.

b) Haikouichthys :
Haikouichthys (fish from Haikou) is another
genus that also appears in the fossil record about
530 Ma, and also marks the transition from
invertebrate to vertebrates.
EARLY FISH ACCORDING TO
GEOLOGICAL TIME SCALE…

c)Myllokunmingia :
Myllokunmingia is a genus that appeared
about 530 Ma. It is a chordate, and it has been
argued that it is a vertebrate

2)Ordovician period:
a)Arandaspis:
Arandaspis are jawless fish that lived in the early
Ordovician period, about 480–470 Ma. It was about 15 cm
(6 in) long, with a streamlined body covered in rows of
knobbly armoured scutes. The front of the body and the
head were protected by hard plates with openings for the
eyes, nostrils and gills.

b)Astraspis:
Astraspis (star shield) is an extinct genus of
primitive jawless fish related to other Ordovician
fishes, such as Sacabambaspis and Arandaspis.
Fossils show clear evidence of a sensory structure
(lateral line system).

c)Thelodonts:
Thelodonts (nipple teeth) are a class of small,
extinct jawless fishes with distinctive scales instead
of large plates of armour. There is debate over
whether these represent a monophyletic grouping, or
disparate stem groups to the major lines of jawless
and jawed fish

3)Silurian period:
a)Anaspida:
Anaspida (without shield) is an extinct class of
primitive jawless vertebrates that lived during the
Silurian and Devonian periods.

b)Osteostraci:
Osteostraci ("bony shields") was a class of bony-
armored jawless fish that lived from the Middle
Silurian to Late Devonian.

c)Spiny shark:
Spiny sharks, more formally called "Acanthodians"
(having spines), constitute the class Acanthodii. They first
appeared by the late Silurian ~420 Ma, and were among
the first fishes to evolve jaws. They share features with
both cartilaginous fish and bony fish, but they are not true
sharks, though leading to them. They became extinct
before the end of the Permian ~250 Ma.

d)Placoderms:
Placoderms, (plate-like skin), are a group of
armoured jawed fishes, of the class Placodermi. The
oldest fossils appeared during the late Silurian, and
became extinct at the end of the Devonian. Recent
studies suggest that the placoderms are possibly a
paraphyletic group of basal jawed fishes.

e)Guiyu oneiros:
Guiyu oneiros, the earliest known bony fish. It has
the combination of both ray-finned and lobe-finned
features, although analysis of the totality of its
features place it closer to lobe-finned fish

3)Devonian periods:(early)
a)Psarolepis:
Psarolepis (speckled scale) is a genus of
extinct lobe-finned fish that lived around 397 to 418
Ma. Fossils of Psarolepis have been found mainly in
South China and described by paleontologist Xiaobo
Yu in 1998.

b)Holoptychius:
Holoptychius is an extinct genus from the order of
porolepiform lobe-finned fish, extant from 416 to 359 Ma.
It was a streamlined predator about 50 centimetres (20 in)
long (though it could grow up to 2.5 m), which fed on other
bony fish. Its rounded scales and body form indicate that it
could have swum quickly through the water to catch prey

c)Petalichthyida:
The Petalichthyida was an order of small,
flattened placoderms that existed from the beginning
of the Devonian to the Late Devonian. They were
typified by splayed fins and numerous tubercles that
decorated all of the plates and scales of their armour.

d)Laccognathus:
Laccognathus (pitted jaw) was a genus of
amphibious lobe-finned fish that existed 398–360 Ma.
They were characterized by the three large pits (fossae)
on the external surface of the lower jaw, which may have
had sensory functions.[Laccognathus grew to 1–2 metres
(3–7 ft) in length. They had very short dorsoventrally
flattened heads, less than one-fifth the length of the body

3)Devonian(mid):
a)Dipterus:
Dipterus (two wings) is an extinct genus of
lungfish from 376–361 Ma. It was about 35
centimetres (14 in) long, mostly ate invertebrates,
and had lungs, not an air bladder.

c)Cladoselache:
Cladoselache was the first abundant genus of
primitive shark, appearing about 370 Ma.

c)Pituriaspida:
Pituriaspida (hallucinogenic shield) is a class
containing two bizarre species of armoured jawless
fishes with tremendous nose-like rostrums. They
lived in estuaries around 390 Ma.

3)Devonian(late):
a)Dunkleosteus:
Dunkleosteus is a genus of arthrodire
placoderms that existed from 380 to 360 Ma. It grew
up to 10 metres (33 ft) long

b)Materpiscis:
Materpiscis (mother fish) is a genus of ptyctodontid
placoderm from about 380 Ma. Known from only one
specimen, it is unique in having an unborn embryo
present inside, and with remarkable preservation of a
mineralised placental feeding structure (umbilical cord).
This makes Materpiscis the first known vertebrate to show
viviparity, or giving birth to live young.

4)Carboniferous period:
a)Stethacanthidae:
As a result of the evolutionary radiation,
carboniferous sharks assumed a wide variety of
bizarre shapes—including sharks of the family
Stethacanthidae.

b)Falcatus:
Falcatus is a genus of small cladodont-toothed
sharks that lived 335–318 Ma. They were about 25–
30 cm (10–12 in) long.They are characterized by the
prominent fin spines that curved anteriorly over their
heads.

5)Permian period:
a)Acanthodes:
Acanthodes are an extinct genus of spiny
shark.It had gills but no teeth and was presumably a
filter feeder.

 Mesozoic era(75-205 Ma)
1)Triassic (205 m.y. ago):
a) Pachycormiformes:
Pachycormiformes are an extinct order of
ray-finned fish that existed from the Middle Triassic to
the K-Pg extinction (below). They were characterized
by serrated pectoral fins, reduced pelvic fins and a
bony rostrum.

b)Pholidophorus:
Pholidophorus was an extinct genus of teleost,
around 40 centimetres (16 in) long, from about 240–
140 Ma.

2)Jurassic period(165 Ma):
a)Ichthyodectidae:
The family Ichthyodectidae (literally "fish-biters")
was a family of marine actinopterygian fish. They first
appeared 156 Ma during the Late Jurassic and
disappeared during the K-Pg extinction event 66 Ma. They
were most diverse throughout the Cretaceous period. E.g.
Ichthyodectidae,Gillicus arcuatus.

3)Cretaceous period(135 Ma):
a)Sturgeon:
True sturgeons appear in the fossil record
during the Upper Cretaceous. Since that time,
sturgeons have undergone remarkably little
morphological change, indicating their evolution has
been exceptionally slow and earning them informal
status as living fossils.

b)Cretoxyrhina:
Cretoxyrhina mantelli was a large shark that lived
about 100 to 82 million years ago, during the mid
Cretaceous period. It is commonly known as the
Ginsu Shark. The specimen consisted of a nearly
complete associated vertebral column and over 250
associated teeth. shark's skeleton is made of
cartilage.

c)Enchodus:
Enchodus is an extinct genus of bony fish. It
flourished during the Upper Cretaceous and was
small to medium in size. One of the genus' most
notable attributes are the large "fangs" at the front of
the upper and lower jaws

d)Ptychodus:
Ptychodus is a genus of extinct hybodontiform
shark that lived from the late Cretaceous to the
Paleogene.

 Cenozoic era:
a)Amphistium:
Amphistium is a 50-million-year-old fossil
fish that has been identified as an early relative of the
flatfish, and as a transitional fossil.

a)Megalodon:
Megalodon is an extinct species of shark that
lived about 28 to 1.5 Ma. It looked much like a stocky
version of the great white shark .

Early Fish Geological Time Scale

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