AMNIOTE LUNGS

EVOLUTION OF FORM AND FUNCTION

The primary focus of the Schachner Lab is the evolution of the amniote respiratory system. We are using methods from various different scientific disciplines to gain insight into the anatomy and physiology of the lungs of extant sauropsids and with these data, attempt to reconstruct the evolutionary history of one of the most morphologically diverse vertebrate organs.

 

PULMONARY STRUCTURAL DIVERSITY in REPTILES & BIRDS

 

Our research group is currently focused on the following questions:

 

1) Why is there so much structural diversity in the sauropsid respiratory system?

 

2) What is the evolutionary history of the respiratory system in Sauropsida?

 

Methods:

 

1) Anatomy: CT, µCT, latex and gross dissection

 

2) Development

3) Paleontology (diversity surveys & secondary inferences)

4) Functional studies

 

Diapsida
Diapsida

Phylogeny for Diapsida showing the lung anatomy of the various groups.

Lizard lungs
Lizard lungs

The 3D anatomy of the savannah monitor lizard, and idealized image of flow patterns

Lungs of the Nile crocodile
Lungs of the Nile crocodile
Flow patterns of the Nile crocodile
Flow patterns of the Nile crocodile
Nile crocodile parabronchi
Nile crocodile parabronchi
Homology
Homology

Proposed homology between the crocodilian and the bird.

C. niloticus
C. niloticus

Partial bronchial tree of the Nile crocodile (the dorsobronchi and ventrobronchi). In: Schachner et al., 2013. PeerJ (see publication list)

Caudal anatomy of the croc lung
Caudal anatomy of the croc lung
Digital Chelydra
Digital Chelydra

Dorsal view of the bronchial tree and shell of a common snapping turtle (Chelydra serpentina)

Morelet's croc bronchial tree
Morelet's croc bronchial tree
Thoracic anatomy of an alligator
Thoracic anatomy of an alligator

Alligator mississippiensis

Domestic chicken
Domestic chicken
Crocodilian comparison
Crocodilian comparison

Alligator mississippiensis vs. Crocodylus niloticus

Holding an adult alligator snapper
Holding an adult alligator snapper
Airflow patterns
Airflow patterns

Diagrammatic airflow patterns in the crocodilian and the bird.

Intubated animals to be scanned
Intubated animals to be scanned
Tortoise CT scan
Tortoise CT scan
Bird scanning
Bird scanning

CT scanning hawks with University of California Berkeley Graduate Student Jessie Atterholt (Wake lab)

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Alligator embryo in the egg
Alligator embryo in the egg
Alligator embryo Stage 18
Alligator embryo Stage 18
Alligator embryo
Alligator embryo
Alligator embryo in the egg
Alligator embryo in the egg

DEVELOPMENTAL APPROACH

 

A joint project with Raul Diaz (Cal State LA) is aimed at investigating lung development in various non-model taxa.

 

 

PALEONTOLOGICAL APPROACH

 

Examination of the thoracic rib and vertebral anatomy of extant archosaurs indicates a relationship between the postcranial axial skeleton and pulmonary anatomy allowing for predictions of the respiratory morphology of extinct taxa. The data from this research thus far suggest a progression from a dorsally immobile thin-walled lung in basal dinosauriform archosaurs towards a small volume-constant avian-style lung in saurischian dinosaurs.

 

 

Dinosauriform vertebrae
Dinosauriform vertebrae
Extant sauropsid vertebrae and lungs
Extant sauropsid vertebrae and lungs
Dinosaur lung evolution
Dinosaur lung evolution
Varanid lungs and vertebrae
Varanid lungs and vertebrae