Michael P. Taylor and Mathew J. Wedel
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Michael P. Taylor and Mathew J. Wedel Re-evaluating “Apatosaurus” minimus, a bizarre Morrison Formation sauropod th diplodocoid and macronarian featur Department of Earth Sciences University of Bristol England College of Osteopathic Medicine of the and College of Podiatric Medicine Western University of Health Sciences California, USA.
description
Re-evaluating “ Apatosaurus ” minimus , a bizarre Morrison Formation sauropod with diplodocoid and macronarian features. Michael P. Taylor and Mathew J. Wedel. Department of Earth Sciences University of Bristol England. College of Osteopathic Medicine of the Pacific - PowerPoint PPT Presentation
Transcript of Michael P. Taylor and Mathew J. Wedel
Michael P. Taylor and Mathew J. Wedel
Re-evaluating “Apatosaurus” minimus,a bizarre Morrison Formation sauropod
with diplodocoid and macronarian features
Department of Earth SciencesUniversity of Bristol
England
College of Osteopathic Medicine of the Pacificand College of Podiatric MedicineWestern University of Health SciencesCalifornia, USA.
The Morrison Formation
1.5 million km2; 9.5 million years (156.3±2 Mya to 146.8±1 Mya)
Many sauropod genera in the Morrison
ValidApatosaurusBarosaurusBrachiosaurusCamarasaurusDiplodocusHaplocanthosaurusSupersaurusSuuwassea
Apatosaurus ajax holotype YPM 1860Cervical vertebra, left lateral view
Many sauropod genera in the Morrison
ValidApatosaurusBarosaurusBrachiosaurusCamarasaurusDiplodocusHaplocanthosaurusSupersaurusSuuwassea
QuestionableAmphicoeliasDyslocosaurus [if Jurassic)]DystrophaeusEobrontosaurus
Amphicoelias fragillimus holotype AMNH 5777Dorsal vertebral neural arch, posterior view
Many sauropod genera in the Morrison
ValidApatosaurusBarosaurusBrachiosaurusCamarasaurusDiplodocusHaplocanthosaurusSupersaurusSuuwassea
SynonymisedAtlantosaurusBrontosaurusCathetosaurusDystylosaurusElosaurusMorosaurusSeismosaurusUintasaurusUltrasauros [sic]
QuestionableAmphicoeliasDyslocosaurus [if Jurassic)]DystrophaeusEobrontosaurus
Dystylosaurus edwini holotype BYU 4503Dorsal vertebral, right anterolateral view
Many sauropod genera in the Morrison
ValidApatosaurusBarosaurusBrachiosaurusCamarasaurusDiplodocusHaplocanthosaurusSupersaurusSuuwassea
SynonymisedAtlantosaurusBrontosaurusCathetosaurusDystylosaurusElosaurusMorosaurusSeismosaurusUintasaurusUltrasauros [sic]
QuestionableAmphicoeliasDyslocosaurus [if Jurassic)]DystrophaeusEobrontosaurus
Many sauropod genera in the Morrison
ValidApatosaurusBarosaurusBrachiosaurusCamarasaurusDiplodocusHaplocanthosaurusSupersaurusSuuwassea
SynonymisedAtlantosaurusBrontosaurusCathetosaurusDystylosaurusElosaurusMorosaurusSeismosaurusUintasaurusUltrasauros [sic]
QuestionableAmphicoeliasDyslocosaurus [if Jurassic)]DystrophaeusEobrontosaurus
Not yet namedNew diplodocoid (Vietti and Hartman 2004)AMNH diplodocine"Apatosaurus" minimus
ApatosaurusApatosaurus Composite skeleton on displayin public gallery at AMNH.
Apatosaurus has many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimus, grandis, laticollis, amplus, alanquerensis
Apatosaurus (= “Brontosaurus”) excelsus holotype YPM 1980
Apatosaurus has many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimus, grandis, laticollis, amplus, alanquerensis
Apatosaurus (= “Brontosaurus”) excelsus holotype YPM 1980
Apatosaurus has many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimus, grandis, laticollis, amplus, alanquerensis
Atlantosaurus montanus, immanis
Brontosaurus Elosaurus
Apatosaurus (= “Brontosaurus”) excelsus holotype YPM 1980
Apatosaurus has many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimus, grandis, laticollis, amplus, alanquerensis
Camarasaurus grandis
Atlantosaurus montanus, immanis
Eobrontosaurus
???
Brontosaurus Elosaurus
Lourinhasaurus
Apatosaurus (= “Brontosaurus”) excelsus holotype YPM 1980
Apatosaurus species
Upchurch et al. (2005)Figure 15.
Specimen-levelphylogenetic analysisStrict consensus
What is AMNH 675?
Henry Fairfield Osborn (1904)Figure 4.
“Anterior, posterior and leftlateral views of the sacrum andilium of Brontosaurus sp.No. 675, Amer. Mus.”
“The inferior view of thesevertebrae corresponds incharacter with Marsh's figuresof Brontosaurus excelsus andof B. amplus.”
What is AMNH 675?
Charles C. Mook (1917)Figure 2.
“A. Outline of right pubisof Apatosaurus minimus.B. Outline of right ischiumof Apatosaurus minimus.”
No reason given forassociation of material.
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
“The inferior portion of the sacral rib of primary sacral 2has an oblique ridge on its inferior surface resemblingthose present in the types of A. ajax, Brontosaurusexcelsus, and B. amplus. This is a characteristic structurein Apatosaurus. The inferior surfaces of the centra arebroadly rounded, contrasting with those of Diplodocus. Theinferior portions of the sacral ribs are not twisted as inCamarasaurus. These characters together with the tallspines which have the characteristic Apatosaurus laminationindicate conclusively that the specimen under considerationbelongs to the genus Apatosaurus.”
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
“The inferior portion of the sacral rib of primary sacral 2has an oblique ridge on its inferior surface resemblingthose present in the types of A. ajax, Brontosaurusexcelsus, and B. amplus. This is a characteristic structurein Apatosaurus. The inferior surfaces of the centra arebroadly rounded, contrasting with those of Diplodocus. Theinferior portions of the sacral ribs are not twisted as inCamarasaurus. These characters together with the tallspines which have the characteristic Apatosaurus laminationindicate conclusively that the specimen under considerationbelongs to the genus Apatosaurus.”
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
“The inferior portion of the sacral rib of primary sacral 2has an oblique ridge on its inferior surface resemblingthose present in the types of A. ajax, Brontosaurusexcelsus, and B. amplus. This is a characteristic structurein Apatosaurus. The inferior surfaces of the centra arebroadly rounded, contrasting with those of Diplodocus. Theinferior portions of the sacral ribs are not twisted as inCamarasaurus. These characters together with the tallspines which have the characteristic Apatosaurus laminationindicate conclusively that the specimen under considerationbelongs to the genus Apatosaurus.”
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
“The inferior portion of the sacral rib of primary sacral 2has an oblique ridge on its inferior surface resemblingthose present in the types of A. ajax, Brontosaurusexcelsus, and B. amplus. This is a characteristic structurein Apatosaurus. The inferior surfaces of the centra arebroadly rounded, contrasting with those of Diplodocus. Theinferior portions of the sacral ribs are not twisted as inCamarasaurus. These characters together with the tallspines which have the characteristic Apatosaurus laminationindicate conclusively that the specimen under considerationbelongs to the genus Apatosaurus.”
Why is AMNH 675 Apatosaurus?
“It appears that the well-preserved sacrum and pelvisof No. 675 of the American Museum collections belongsto a species of Apatosaurus which has not hithertobeen described.”
“The inferior portion of the sacral rib of primary sacral 2has an oblique ridge on its inferior surface resemblingthose present in the types of A. ajax, Brontosaurusexcelsus, and B. amplus. This is a characteristic structurein Apatosaurus. The inferior surfaces of the centra arebroadly rounded, contrasting with those of Diplodocus. Theinferior portions of the sacral ribs are not twisted as inCamarasaurus. These characters together with the tallspines which have the characteristic Apatosaurus laminationindicate conclusively that the specimen under considerationbelongs to the genus Apatosaurus.”
Not very convincing
Not very convincing
“Apatosaurus” minimusholotype AMNH 675,sacrum in right lateral view.
“Apatosaurus” minimus holotype AMNH 675, sacrum in left lateral view.
Real? Fabricated?
“Apatosaurus” minimus holotype AMNH 675, left ischium in medial view.
“Apatosaurus” minimus holotypeAMNH 675, left ischium in posterior view.
“Apatosaurus” minimusholotype AMNH 675, left ischium
“Apatosaurus” minimusholotype AMNH 675, incomplete rightischium
“True medial”
“Apatosaurus” minimusholotype AMNH 675, partial left pubis
“Apatosaurus” minimusholotype AMNH 675, Composite pelvis
“Apatosaurus” minimusholotype AMNH 675, Composite pelvis
Slightly foreshortened,But effect is not great.
e.g. inclined inward 20°cos(20°) = 0.94So orthogonal length is 94%
“Apatosaurus” minimusholotype AMNH 675, Composite pelvis
Slightly foreshortened,But effect is not great.
e.g. inclined inward 20°cos(20°) = 0.94So orthogonal length is 94%
Out of proportion.Is the associationgood?
Is it Apatosaurus?
“The species cannot belong to Apatosaurus ... The ilia are low,and their preacetabular processes are directed stronglylaterally somewhat as in the titanosaurids.”
– McIntosh 1990a (The Dinosauria, 1st ed.)
“From the shape of the distal end of the ischium and varioussacral characters, particularly the height of the neuralspines, it is now clear that this animal is not Apatosaurus,and also must be excluded from the Diplodocidae.”
– McIntosh 1990b:59
“The pubis has an ischial articular surface whose length isnearly 50% of the length of this element, a derived conditionin Camarasauromorpha (one of several features distinguishing“A.” minimus from Apatosaurus at the generic or highertaxonomic levels). ... This form is perhaps a basal macronarianor basal camarasauromorph.”
– Upchurch et al. 2004 (The Dinosauria, 2nd ed.)
Is it Apatosaurus?
“The species cannot belong to Apatosaurus ... The ilia are low,and their preacetabular processes are directed stronglylaterally somewhat as in the titanosaurids.”
– McIntosh 1990a (The Dinosauria, 1st ed.)
“From the shape of the distal end of the ischium and varioussacral characters, particularly the height of the neuralspines, it is now clear that this animal is not Apatosaurus,and also must be excluded from the Diplodocidae.”
– McIntosh 1990b:59
“The pubis has an ischial articular surface whose length isnearly 50% of the length of this element, a derived conditionin Camarasauromorpha (one of several features distinguishing“A.” minimus from Apatosaurus at the generic or highertaxonomic levels). ... This form is perhaps a basal macronarianor basal camarasauromorph.”
– Upchurch et al. 2004 (The Dinosauria, 2nd ed.)No.No.“The species cannot belong to Apatosaurus ... The ilia are low,and their preacetabular processes are directed stronglylaterally somewhat as in the titanosaurids.”
– McIntosh 1990a (The Dinosauria, 1st ed.)
“From the shape of the distal end of the ischium and varioussacral characters, particularly the height of the neuralspines, it is now clear that this animal is not Apatosaurus,and also must be excluded from the Diplodocidae.”
– McIntosh 1990b:59
“The pubis has an ischial articular surface whose length isnearly 50% of the length of this element, a derived conditionin Camarasauromorpha (one of several features distinguishing“A.” minimus from Apatosaurus at the generic or highertaxonomic levels). ... This form is perhaps a basal macronarianor basal camarasauromorph.”
– Upchurch et al. 2004 (The Dinosauria, 2nd ed.)
Apatosaurus excelsus“Apatosaurus” minimus
Diplodocus carnegii“Apatosaurus” minimus
Dicraeosaurus hansemanni“Apatosaurus” minimus
Haplocanthosaurus priscus“Apatosaurus” minimus
Camarasaurus lentus (subadult)“Apatosaurus” minimus
Giraffatitan brancai“Apatosaurus” minimus
Rapetosaurus krausei“Apatosaurus” minimus
Mamenchisaurus hochuanensis“Apatosaurus” minimus
Seems to be something new
McIntosh 1990a (Dinosauria, 1st ed.)Fig. 16.13: comparison of ilia
Tall, narrow neural spines on wide sacrumTall, narrow neural spines on wide sacrum
Sacral plates do not extend to iliumSacral plates do not extend to ilium
““Turtle-mimic” rugosities on sacral platesTurtle-mimic” rugosities on sacral plates
“Turtle-mimic” rugosities on sacral plates
Long, low ilium
Ilium vertical even while flaring.
Lateral “shelf” on bottom of iliumLateral “shelf” on bottom of ilium
Lateral “shelf” on bottom of iliumLateral “shelf” on bottom of iliumLateral “shelf” on bottom of ilium
Pubic pedunclePubic pedunclePubic peduncle
Lateral foramina (“pleurocoels”) absentfrom S1 and S6
Mike: We have an identification problem
Mike: We have an identification problem
Matt: Let's use cladistics!
Mike: We have an identification problem
Matt: Let's use cladistics!
Mike: Now we have two problems.
Analysis of Taylor (2009) after Harris (2006)
Strict consensusof 107 MPTs
Analysis of Taylor (2009) after Harris (2006)
Strict consensusof 107 MPTs
Neosauropoda inBig polytomy
Macronaria dissolved
Analysis of Taylor (2009) after Harris (2006)
Strict consensusof 107 MPTs
Neosauropoda inBig polytomy
BrachiosauridaeRebbachisauridae
Flagellicaudata
Macronaria dissolved
Analysis of Taylor (2009) after Harris (2006)
50% majority rule consensusof 107 MPTs
Analysis of Taylor (2009) after Harris (2006)
50% majority rule consensusof 107 MPTs
Neosauropoda backin shape
Analysis of Taylor (2009) after Harris (2006)
85 trees (79%)
50% majority rule consensusof 107 MPTs
Neosauropoda backin shape
Is “Apatosaurus” minimus a saltasaurid?It's an appealing idea.Would be first Morrison titanosaur
Is “Apatosaurus” minimus a saltasaurid?It's an appealing idea.Would be first Morrison titanosaur
SaltasaurusPhoto by Randy Irmis
Is “Apatosaurus” minimus a saltasaurid?
Opisthocoelicaudia zdanskyi
Is “Is “ApatosaurusApatosaurus” ” minimusminimus a saltasaurid? a saltasaurid?
Opisthocoelicaudia Opisthocoelicaudia zdanskyizdanskyi
Is “Is “ApatosaurusApatosaurus” ” minimusminimus a saltasaurid? a saltasaurid?
Opisthocoelicaudia Opisthocoelicaudia zdanskyizdanskyi
No.No.
Analysis of Taylor (2009) after Harris (2006)
50% majority rule consensusof 107 MPTs
Analysis of Taylor (2009) after Harris (2006)
50% majority rule consensusof 107 MPTs
On changing onequestionable character
Analysis of Whitlock (2011)Strict consensus of 3 MPTs
Only polytomy is withinDiplodocinae
Analysis of Whitlock (2011)Strict consensus of 3 MPTs
Only polytomy is withinDiplodocinae
Basal diplodocoid(sister to Flagellicaudata)
Analysis of Whitlock (2011)Strict consensus of 3 MPTs
Only polytomy is withinDiplodocinae
Basal diplodocoid(sister to Flagellicaudata)
But only a tiny sampleof macronarians
Analysis of Whitlock (2011)
Back to analysis of Taylor (2009)
85 trees (79%)
50% majority rule consensusof 107 MPTs
Back to analysis of Taylor (2009)
85 trees (79%)
50% majority rule consensusof 107 MPTs
Other MPTs
Interim conclusion
Cladistics is no substitutefor actual palaeontology.
Key split: Diplodocoidea vs. Macronaria
Dip
lodoco
idea
Macro
naria
It's a diplodocoid!
Neural spines tall, narrow, laminated as in diplodocoids
Neural spines tall, narrow, laminated as in diplodocoids
Neural spines tall, narrow, laminated as in diplodocoids
Neural spines tall, narrow, laminated as in diplodocoids
Neural spines laminated as in diplodocoids
Distal end of right ischium
'V'-shaped distal articulation of ischia
It's a macronarian!
Six fully fused sacrals connecting to ilium
Ilium without distal expansion
Diplodocus sacrum AMNH 3532, anterior
Diplodocus sacrum AMNH 3532, anterior
“Apatosaurus” minimus and Diplodocus sacra
“Apatosaurus” minimus and Diplodocus sacra
“Apatosaurus” minimus and Diplodocus sacra
“A.” minimus and Apatosaurus sacra
Apatosaurus parvussacrum and fused ilia(Gilmore 1936: fig. 31)
Do not mess with Gilmore.
GILMORE SAYSGILMORE SAYS
REJECT WITHOUT REVIEW.REJECT WITHOUT REVIEW.
Apatosaurus ajax “Tokyo specimen”
Diplodocus“Apatosaurus” minimus
Tokyo Apatosaurus ajax Apatosaurus parvus
Nearly at the conclusions ...
1. “Apatosaurus” minimus ain't Apatosaurus.
2. In fact, it's not any known sauropod.
3. Heck if we know what it is.
Sauropod diversity still underestimated
Underestimated even in the Morrison
Sauropod diversity still underestimated
Underestimated even in the Morrison
Sauropod diversity still underestimated
Just like it's underestimated in the Early Cretaceous North America
+ Yellow Cat camarasaur (Britt?)+ Yellow Cat brachiosaur (Britt?)+ Yellow Cat titanosaur (Britt?)+ Long Walk brachiosaur (Tidwell?)+ CEU brachiosaur (Burge? Bird?)+ Cloverly 2nd sauropod (D'Emic?)
Sauropod diversity still underestimated
Just like it's underestimated in the Wealden
+ “Pelorosaurus” becklesi+ the Barnes High sauropod+ a titanosaur based on good caudals+ those “Eucamerotus” dorsals etc.
Sauropod diversity still underestimated
Is it underestimated everywhere?
Is it underestimated everywhere?
Sauropod diversity still underestimated
Is it underestimated everywhere?
Is it underestimated everywhere?
… whatever Horner says.
AcknowledgementsAcknowledgements
Mark Norell and Carl Mehlingfor access to the specimen.
AcknowledgementsAcknowledgements
Mark Norell and Carl Mehlingfor access to the specimen.
Some sauropod genera have many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimusBarosaurus lentus, ?affinis, ?africanus, ?gracilisBrachiosaurus altithorax, ?brancai, ?fraasi, ?nougaredi, ?atalaiensisCamarasaurus supremus, grandis, lentus, ?lewisiDiplodocus longus, ?carnegii, hayi, hallorumHaplocanthosaurus priscus, ?utterbacki, delfsiSupersaurus vivianaeSuuwassea emilieae
Some sauropod genera have many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimusBarosaurus lentus, ?affinis, ?africanus, ?gracilisBrachiosaurus altithorax, ?brancai, ?fraasi, ?nougaredi, ?atalaiensisCamarasaurus supremus, grandis, lentus, ?lewisiDiplodocus longus, ?carnegii, hayi, hallorumHaplocanthosaurus priscus, ?utterbacki, delfsiSupersaurus vivianaeSuuwassea emilieae
Some sauropod genera have many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimusBarosaurus lentus, ?affinis, ?africanus, ?gracilisBrachiosaurus altithorax, ?brancai, ?fraasi, ?nougaredi, ?atalaiensisCamarasaurus supremus, grandis, lentus, ?lewisiDiplodocus longus, ?carnegii, hayi, hallorumHaplocanthosaurus priscus, ?utterbacki, delfsiSupersaurus vivianaeSuuwassea emilieae
Brontosaurus Elosaurus Morosaurus Cathetosaurus
Seismosaurus
Some sauropod genera have many species
Apatosaurus ajax, excelsus, lousiae, parvus, ?yahnahpin, ?minimusBarosaurus lentus, ?affinis, ?africanus, ?gracilisBrachiosaurus altithorax, ?brancai, ?fraasi, ?nougaredi, ?atalaiensisCamarasaurus supremus, grandis, lentus, ?lewisiDiplodocus longus, ?carnegii, hayi, hallorumHaplocanthosaurus priscus, ?utterbacki, delfsiSupersaurus vivianaeSuuwassea emilieae
Giraffatitan
Tornieria
?
Lusotitan
Eobrontosaurus
???
Brontosaurus Elosaurus Morosaurus Cathetosaurus
Seismosaurus
“Turtle-mimic” rugosities on sacral plates
“Turtle-mimic” rugosities on sacral plates
Lateral “shelf” on bottom of iliumLateral “shelf” on bottom of ilium
Lateral “shelf” on bottom of ilium
