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A new paper in the journal Science on stem tetrapods includes Lauer Foundation Specimens

  • 6 days ago
  • 2 min read

Updated: 11 hours ago

Dr. Jason Pardo and  Lauer Foundation Research Associate Dr. Arjan Mann have published a paper in the Journal Science title “Direct development of stem tetrapods across the fin-to-limb transition”.  This paper includes important specimens from the Lauer Foundation collections. Two specimens were figured and two referenced.


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Summary of the paper:

Modern amphibians are characterized by an aquatic larval stage that ends abruptly with a period of widespread tissue remodeling (metamorphosis) upon transition to terrestrial adulthood. A transient larval stage ending in gradual metamorphosis is often assumed for the earliest digited tetrapods, but direct evidence of this larval stage is lacking. Exceptionally preserved stem tetrapod hatchlings show that a transient larval stage was absent in tetrapods both before and after the fin-to-limb transition; instead we identified soft-and hard tissue evidence of direct development, falsifying hypotheses of an ancestral origin of metamorphosis or of a gradual larval-postlarval transition serving as a template for lissamphibian metamorphosis. We argue that a transient larval period culminating in metamorphosis originated near or within the tetrapod crown group as part of a broader suite of traits associated with terrestrialization.


A new paper in the journal Science on stem tetrapods includes Lauer Foundation Specimens
Fig. 3. Early posthatching morphology of other Mazon Creek sarcopterygians. (A) Megalichthyid hatchling stage, LF 677, aggregation of eight individuals. (B) Megalichthyid early feeding stage, FMNH PF 3028. (C) Megalichthyid active locomotory stage, MPM VP 359216. (D) Hatchling stage of amphibamiform amphibian, LF 1232. (E) Early feeding stage of amphibamiform, FMNH PR 5085. (F) Early juvenile (premetamorphic) stage of amphibamiform, FMNH PR 664. (G) Postmetamorphic adult stage of amphibamiform Amphibamus grandiceps, FMNH PR 4202. (H) Early feeding stage of probable ctenodontid lungfish, FMNH PF 16088. (I) Early hatchling stage of aïstopod, USNM PAL 785706. (J) Active locomotory larva of dvinosaur Isodectes obtusus, FMNH PR 1659. Scale bars, 10 mm. Abbreviations: bd, branchial, denticles; cf, caudal fin; d, dentary; dv, dorsal vertebrae; eg, external gills; eye, retinal pigments of eye; f, femur; gt, gut trace; h, humerus; il, ilium; lip, lip fold; ol, olfactory lobe; op, operculum; pel, pelvic fin; pf, pectoral fin; pt, pterygoid; sph, sphenoid bone; sr, skull roof. [Image in (A) provided by the Lauer Foundation]

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