Selective Factors Associated with the Origin of Fur and Feathers1

  title={Selective Factors Associated with the Origin of Fur and Feathers1},
  author={John A. Ruben and Terry D. Jones},
Abstract Conventional wisdom notwithstanding, fur and feathers are unlikely to have arisen in direct association with elevated metabolic rates in early mammals, birds, or their ancestors. A complete insulative fur coat probably appeared first in the earliest mammals long after mammalian ancestors (therapsids) had attained mammalian, or near-mammalian, metabolic rates. The evolution of feathers was unlinked to the evolution of modern avian metabolic rates since early, fully flighted birds (i.e… 

Phylogenetic Context for the Origin of Feathers 1

Current evidence strongly suggests that birds are theropod dinosaurs, and that the most primitive known feathers are found on nonflying animals, which suggests that feathers did not evolve as flight structures.

Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence

It is suggested that Aves plus bird‐like maniraptoran theropods (e.g., microraptors and others) may be a separate clade, distinctive from the main lineage of Theropoda, a remnant of the early avian radiation, exhibiting all stages of flight and flightlessness.

Hypothesis: Avian flight originated in arboreal archosaurs gliding on membranous wings

The oldest feathers known to date have been found in archosaurs capable of flight. However, some of them (scansoriopterygids) flew by the use of a membrane rather than feathers. We therefore propose

The Evolution of Endothermy in Terrestrial Vertebrates: Who? When? Why?

The fossil record of nonmammalian synapsids suggests that at least two Late Permian lineages possessed incipient respiratory turbinates, but this suggests that dinosaurs and nonornithurine birds generally lacked the capacity for high, avian‐like levels of sustained activity, although the aerobic capacity of theropods may have exceeded that of extant ectotherms.

Mammalian skin evolution: a reevaluation

  • P. Maderson
  • Environmental Science, Biology
    Experimental dermatology
  • 2003
It is now proposed that multiplication of sensory protohairs caused by mutations in patterning genes initially protected the delicate barrier tissues and eventually produced the minimal morphology necessary for an insulatory pelage.

Revisiting life history and morphological proxies for early mammaliaform metabolic rates

Availabledata suggest that metabolic rates play little role in affecting longevity within and between tetrapod classes once the effects of body size are properly accounted for, and contend that high longevity cannot be taken as a proxy for low metabolic rates.

Limb proportions and avian terrestrial locomotion

It is concluded that birds (Archaeopteryx + crownclade Aves) are a subgroup of the theropod dinosaurs and feathers cannot be used to define birds, as is traditionally advocated.

A Phylogenetic Perspective on Locomotory Strategies in Early Amniotes

This work investigates the major locomotory strategies that have been posited for Paleozoic amniotes by optimizing the major Locomotory styles identified for these taxa onto the consensus tree, in order to present an overview of the pattern of evolution of locomOTory strategies inherited and adopted by various amniote lineages.

Gravity-defying Behaviors: Identifying Models for Protoaves1

The more traditional model for the origin of flight derives birds from among small arboreal early Mesozoic archosaurs (“thecodonts”) via a series of intermediate stages, such as leaping, parachuting, gliding, and flapping.

A Phylogenetic Perspective on Locomotory Strategies in Early Amniotes1

Using a phylogeny representing the current consensus in the literature, the major locomotory strategies that have been posited for Paleozoic amniotes are investigated by optimizing the major Locomotory styles identified for these taxa onto the consensus tree in order to present an overview of the pattern of evolution of locomOTory strategies inherited and adopted by various amniote lineages.



Respiratory physiology of the dinosaurs

The apparent absence of respiratory turbinates in dinosaurs, as well as likely ectothermic patterns of thermoregulation in very early birds, argues strongly that these animals were unlikely to have achieved the metabolic status of modern terrestrial endotherms.

The Origin of Birds and of Avian Flight

I do not discuss pterosaurs, lizards, and mammals as possible ancestors because they have never enjoyed serious support as bird relatives and I have not discovered anything to make me think that they deserve any.

The relative timing of the origin of flight and endothermy: evidence from the comparative biology of birds and mammals.

Evidence from the comparative biology of living birds and mammals suggests that in the animals ancestral to birds the adaptations for high energy flow were constrained from the start by the need for acrodynamic stability, i.e. flight was initiated before endothermy.

The Metabolic Status of Some Late Cretaceous Dinosaurs

Analysis of the nasal region in fossils of three theropod dinosaurs and one ornithischian dinosaur showed that their metabolic rates were significantly lower than metabolic rates in modern birds and mammals.

Two feathered dinosaurs from northeastern China

Two theropods from the Upper Jurassic/Lower Cretaceous Chaomidianzi Formation of Liaoning province, China are described, which represent stages in the evolution of birds from feathered, ground-living, bipedal dinosaurs.


  • W. J. Hillenius
  • Biology, Environmental Science
    Evolution; international journal of organic evolution
  • 1994
The presence of respiratory turbinals in these advanced mammallike reptiles suggests that the evolution of “mammalian” oxygen consumption rates may have begun as early as the Late Permian and developed in parallel in therocephalians and cynodonts.

Sordes pilosus and the nature of the pterosaur flight apparatus

IT is now generally accepted that pterosaurs, Mesozoic reptiles, were true fliers, but the nature of their flight apparatus is still much disputed. Evidence has been presented in favour of bird-like

The Evolution of Endothermy in the Phylogeny of Mammals

  • B. McNab
  • Environmental Science, Biology
    The American Naturalist
  • 1978
It is concluded that many of the characteristics that distinguish mammals from reptiles, including endothermy, viviparity, and even lactation, may be related to the marked decrease in body size that occurred in the evolution of mammals from advanced therapsids.

Archaeopteryx and the origin of birds

Analysis of the five presently known skeletal specimens of Archaeopteryx confirm the conclusions (long rejected by most subsequent workers) of Heilmann (1926), Lowe (1935, 1944, 1944) and Holmgren (1955), namely, that the skeletal anatomy of Archaeipteryx is extraordinarily similar to that of contemporaneous and succeeding coelurosaurian dinosaurs.

The evolution of endothermy in mammals and birds: from physiology to fossils.

  • J. Ruben
  • Environmental Science, Biology
    Annual review of physiology
  • 1995
Endothermic warm­ bloodedness or, more correctly, endothermic homeothermy generally results from a combination of high resting, aerobically supported heat production rates in virtually all soft tissues, and insulation sufficient to retard excessive heat loss.