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OstracodermsA DIVERSE ASSEMBLY OF  ANCIENT ARMOURED      CRANIATES
TAXONOMY Domain: Eukarya    Kingdom: Animalia         Phylum: Chordata              Subphylum: Vertebrata                 ...
Characteristics Oldest known craniates Date back to the middle of Ordovician until the  end of Devonian Entire body was...
 Probably were slow, bottom-dwelling animals Have median fins located down the midline of  their backs Gills were locat...
 Used muscular gill pouch to pull in small and slow moving prey
Examples of the extinct   Ostracoderms
According to E.A. Stensiö – paleontologist at the            University of Stockholm Head skeleton of cephalaspis (one sp...
lateral fieldnostril          eye                            Dorsal field           Pineal foramen
 The body shield turned along its lateral edges Beneath the gills the body covering were tile  like scales A small mout...
 Head contained an endoskeleton of endochondral bone and considerable cartilage
Acanthodians
Acanthodians? Class of Extinct species Share features with Bony and Cartilaginous  fishes      In form they resemble sha...
Acanthodians Like Ostracoderms, their head and body were protected by a dermal armor of bony plates and scales
Acanthodians Acanthodians did have cartilaginous skeletons But their fins are bony based with a dentine spine Most Acan...
Diplacanthus longispinus
Orders Climatiiformes   had shoulder armor and many small sharp spines Ischnacanthiformes     Had teeth fused to the ja...
 Spiny Sharks   they were superficially shark-shaped, with a streamlined body,    paired fins, and a strongly upturned t...
Brief History Despite being called "spiny sharks," acanthodians  predate sharks. They evolved in the sea at the  beginnin...
 Many paleonthologists consider that the acanthodians were close to the ancestors of the bony fishes. Although their inte...
PLACODERMS
TAXONOMY Domain: Eukarya    Kingdom: Animalia         Phylum: Chordata              Subphylum: Vertebrata                 ...
Placoderms Greek word “tablet & skin” referring to  their heavy armoured bony plates an extinct class of armored fishes...
Distinct Characteristics layer of segmented armor across the  head and thorax 2 paired fins Depending on species, the r...
Dunkleosteus sp.            Order Arthrodira
Order Arthrodira Best known placoderms A heavy dermal shield covered the head  and gill region and another covered much ...
 shark-like bodies Some very large – e.g. Dunkleosteus and Gorgonichthys to 6 - 9 m The gigantic superpreditor Dunkleost...
Coccosteus sp.
Gorgonichthys sp.                                         Reconstruction                                         of placo...
Order Antiarchi Were small placoderms    reach a length of 15-20    feet but majority were    shorter   Exhibit atypical...
Order RhenanidaCharacteristics of Rhenanids: reduction of the thoracic  armour Body is covered by small  tesserae (small...
Order Petalichthyida Closely related to    arthrodires   Rarely exceeds a meter   They are freshwater bottom    dweller...
Order Acanthothoraci Generalized by a stout  spine emanating from the  median dorsal plate Some acanthothoracids  are si...
Order Ptyctodontida have enlongate bodies whip-like tails reduced head thoracic armor Exhibits sexual  dimorphism ma...
SUMMARYOrder Arthrodira (Arthrodires)– jointed neck–movable joint between the head and the thoracic bodyOrder Antiarchi (A...
DifferencesOstracoderms      Acanthodians      Placoderms-oldest known     -oldest jawed     -First animals tovertebrate  ...
Comp.ana. ostracoderms,acanthodians,placoderms
Comp.ana. ostracoderms,acanthodians,placoderms
Comp.ana. ostracoderms,acanthodians,placoderms
Comp.ana. ostracoderms,acanthodians,placoderms
Comp.ana. ostracoderms,acanthodians,placoderms
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Comp.ana. ostracoderms,acanthodians,placoderms

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Comp.ana. ostracoderms,acanthodians,placoderms

  1. 1. OstracodermsA DIVERSE ASSEMBLY OF ANCIENT ARMOURED CRANIATES
  2. 2. TAXONOMY Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Superclass: Agnatha Class: Ostracodermi
  3. 3. Characteristics Oldest known craniates Date back to the middle of Ordovician until the end of Devonian Entire body was covered with bony dermal armour Bony shield head covering Lacked jaws Most lacked paired fins Mostly 2-3 cm long; a few reached up to 2 m long Heterocercal tail
  4. 4.  Probably were slow, bottom-dwelling animals Have median fins located down the midline of their backs Gills were located in pouches Cartilaginous internal skeletons A paired of side flaps aid in steering Mouth served to obtain oxygen and retain bits of food and was permanently open Gills were used exclusively for respiration
  5. 5.  Used muscular gill pouch to pull in small and slow moving prey
  6. 6. Examples of the extinct Ostracoderms
  7. 7. According to E.A. Stensiö – paleontologist at the University of Stockholm Head skeleton of cephalaspis (one species of an ostracoderm) was more or less flattened denticle-covered body shield with four dorsal apertures  Two dorsal apertures accommodated a pair of upward-staring eyes  One accommodated the median or pineal eye  Another accommodated a small, anterior opening that was a single naris from which a nasohypophyseal duct led to an olfactory sac and beyond
  8. 8. lateral fieldnostril eye Dorsal field Pineal foramen
  9. 9.  The body shield turned along its lateral edges Beneath the gills the body covering were tile like scales A small mouth that is lined by gills opens to the oropharyngeal chamber is found between the anterior edge of the shield and the scales Curved row external gill slits extends from the corners of the mouth to the caudal margin of the head shield
  10. 10.  Head contained an endoskeleton of endochondral bone and considerable cartilage
  11. 11. Acanthodians
  12. 12. Acanthodians? Class of Extinct species Share features with Bony and Cartilaginous fishes In form they resemble sharks, but theirepidermis was covered by tiny rhomboid platelets likethe scales of holosteans.Oldest jawed fishesHolosteans – Bony fishes (Gars, Bowfins)
  13. 13. Acanthodians Like Ostracoderms, their head and body were protected by a dermal armor of bony plates and scales
  14. 14. Acanthodians Acanthodians did have cartilaginous skeletons But their fins are bony based with a dentine spine Most Acanthodians have heterocercal caudal fins. Silurian to Permian Period. Marine/Freshwater  -Devonian Period: Freshwater species became dominant
  15. 15. Diplacanthus longispinus
  16. 16. Orders Climatiiformes  had shoulder armor and many small sharp spines Ischnacanthiformes Had teeth fused to the jawAcanthodiformes filter feeders, with no teeth in the jaw, but long gill rakers.
  17. 17.  Spiny Sharks  they were superficially shark-shaped, with a streamlined body, paired fins, and a strongly upturned tail; stout bony spines supported all the fins except the tail - hence, "spiny sharks".  However, they were not sharks. Skeleton consisted of bone and cartilage. They had a large operculum.
  18. 18. Brief History Despite being called "spiny sharks," acanthodians predate sharks. They evolved in the sea at the beginning of the Silurian Period, some 50 million years before the first sharks appeared. Later the acanthodians colonized fresh waters, and thrived in the rivers and lakes during the Devonian Period. But the first bony fishes were already showing their potential to dominate the waters of the world, and their competition proved too much for the spiny sharks, which died out in Permian times (approximately 250 MYA).
  19. 19.  Many paleonthologists consider that the acanthodians were close to the ancestors of the bony fishes. Although their interior skeletons were made of cartilage, a bonelike material had developed in the skins of these fishes, in the form of closely fitting scales. Some scales were greatly enlarged and formed a bony covering on top of the head and over the lower shoulder girdle. Others developed a bony flap over the gill openings analogous to the operculum in later bony fishes.
  20. 20. PLACODERMS
  21. 21. TAXONOMY Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Placodermi Order: Arthrodira Order Antiarchi Order Rhenanida Order Petalichthyida Order Acanthothoraci Order Ptyctodontida
  22. 22. Placoderms Greek word “tablet & skin” referring to their heavy armoured bony plates an extinct class of armored fishes Placoderms evolved from agnathan (jawless) fishes Abundant in the fresh waters of the Devonian era First to evolve true jaws First animals to exhibit internalize egg fertilization
  23. 23. Distinct Characteristics layer of segmented armor across the head and thorax 2 paired fins Depending on species, the remainder of the body would be scaled or naked. sharpened points of bone which protrude from the head to grind their food.
  24. 24. Dunkleosteus sp. Order Arthrodira
  25. 25. Order Arthrodira Best known placoderms A heavy dermal shield covered the head and gill region and another covered much of the trunk 2 shield meet in a movable joint Remainder of the body: covered with smaller bony scales or,in late species, was naked. 2 pairs upper jaw tooth plates
  26. 26.  shark-like bodies Some very large – e.g. Dunkleosteus and Gorgonichthys to 6 - 9 m The gigantic superpreditor Dunkleosteus terrelli
  27. 27. Coccosteus sp.
  28. 28. Gorgonichthys sp.  Reconstruction of placoderm Gorgonichthys, Cleveland Shale - copyright John Long, Museum Victoria Gorgonichthys sp.
  29. 29. Order Antiarchi Were small placoderms reach a length of 15-20 feet but majority were shorter Exhibit atypical pectoral fins & dorsal eyes Have flattened ventral surface Suggested to be bottom Bothriolepis Canadensi feeders Have eyes on top of their heads Pectoral fins are enclosed in bony appendages
  30. 30. Order RhenanidaCharacteristics of Rhenanids: reduction of the thoracic armour Body is covered by small tesserae (small square of stones) dorso-ventrally flattened shape enlarged pectoral fins known from marine environments and probably pursued a ray-like benthic lifestyle Rhenanida, Gemuendina sp.
  31. 31. Order Petalichthyida Closely related to arthrodires Rarely exceeds a meter They are freshwater bottom dwellers Unlike the Arthrodires, they are bottom-feeding fish Flattened fish with short trunk and long, spine-like plates. The nostrils and the anterior part of the head shield around the orbits, is covered by a number of tiny scales, Lunaspis sp. as is the long trunk.
  32. 32. Order Acanthothoraci Generalized by a stout spine emanating from the median dorsal plate Some acanthothoracids are similar to rays, expanded pectoral fins and flattened appearance Long head shields, very shortened trunk Brindabellaspis stensioi With eyes and nares pointing upwards, suggesting a bottom dweller
  33. 33. Order Ptyctodontida have enlongate bodies whip-like tails reduced head thoracic armor Exhibits sexual dimorphism males of one ptyctodontid, Rhamphod Rhamphodopis opis, have clasper-like intromittent organs similar to those found sharks and their kins
  34. 34. SUMMARYOrder Arthrodira (Arthrodires)– jointed neck–movable joint between the head and the thoracic bodyOrder Antiarchi (Antiarchs)– pectoral fins are enclosed in bony tubes (pectoral appendages)Order Rhenanida(Rhenanids)– enlarged pectoral fins– body covered by unfused scalesOrder Petalichthyida (Petalichthyids)– typified by their splayed (spread out) finsOrder Acanthothoraci– spiny trunkOrder Ptyctodontida– some species exhibit sexual dimorphism– has beak-like mouth
  35. 35. DifferencesOstracoderms Acanthodians Placoderms-oldest known -oldest jawed -First animals tovertebrate fishes exhibit-jawless fishes -their skeleton internalize egg-lacked paired consist of bone fertilizationfins and cartilage -armored fishes with jaws

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