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Home , Ambulocetus, Archaeoceti, Indohyus, Maiacetus, Protocetidae

Examples Genetics Refs

Unit 2: Transmission Genetics

Lecture 2.6: Evidence for Evolution

John D. Nagy

BIO 181: General Biology for Majors, Scottsdale Community College

2020 Revision

John Nagy Lec 2.6: Evidence for Evolution 1/36 Fossils Examples Genetics Refs Outline

1 Some interesting fossils Synapomorphies Body plan Vestiges Timeline

2 Examples Avians Tetrapods

3 Molecular Genetic Evidence

4 Literature cited

John Nagy Lec 2.6: Evidence for Evolution 2/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline What kind of creature is this?

John Nagy Lec 2.6: Evidence for Evolution 3/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Indohyus

“Indohyus was an similar in size to a but quite different from a cat in shape. It had a long snout and a long tail and long slender limbs. At the end of each limb, there were four or five toes that ended in hoof, similar to that of a deer” [11, pg. 274]. The ear have a “thickened wall. . . called the [which] is present in all cetaceans, and recent. The involucrum is not present in other mammals, except for one: Indohyus” [11, pg. 275].

John Nagy Lec 2.6: Evidence for Evolution 4/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Ventral (underneath) view of dog cranium

The ear bones Thewissen et al. [11] refer to are auditory bullae.

So Indohyus is a racoon-shaped with hooves like a deer and ear bones like a . John Nagy Lec 2.6: Evidence for Evolution 5/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline What kind of creature is this?

John Nagy Lec 2.6: Evidence for Evolution 6/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline

Ambulocetus was “roughly the size of a large male ” [11, pg. 279]. “Toes are terminated by a short phalanx carrying a convex hoof” [12, pg. 211]. “The [auditory] bulla has a thick and massive involucrum on its medial side” [9, pg. 726]. ‘[T]the lower jaw and the auditory bulla have a bony contact unlike any other cetacean” [9, pg. 726].

John Nagy Lec 2.6: Evidence for Evolution 7/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Ambulocetus

“In hunting behavior, Ambulocetus may have been similar to a modern , and, externally, Ambulocetus may have looked like a crocodile” [11, pg. 279]

John Nagy Lec 2.6: Evidence for Evolution 8/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Ventral view of. . . what is that?

Where are the auditory (tympanic) bullae?

John Nagy Lec 2.6: Evidence for Evolution 9/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Ventral view of bottlenose (Tursiops truncatus)

The auditory bullae have fallen off. They are not attached to the skull.

John Nagy Lec 2.6: Evidence for Evolution 10/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Cetaceans have weird, unique ears

Cetacean auditory bullae are unique because they are are very thick on one side; they have an involucrum (red arrows); not attached or poorly attached to the skull. (A) and (B): Fossil ; (C): whale; (D): Right whale; (E) and (F): Fossil toothed whales.

John Nagy Lec 2.6: Evidence for Evolution 11/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Summary of observations so far

Shared traits collect naturally into groups: Indohyus and Ambulocetus all had hooves, like the rest of the Artiodactyla (group including hoofed mammals with an even number of toes). Indohyus, Ambulocetus and the rest of the (whales, and ) had thick auditory bullae with in an involucrum. Definition: Synapomorphy Shared, derived characters like these group organisms into natural catagories. They are called synapomorphies.

John Nagy Lec 2.6: Evidence for Evolution 12/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Another interesting fossil—Basilosaur

These species “have a nasal opening that has shifted back far toward the eyes to form a blowhole and have flippers for forelimbs, a fluke at the end of the tail” [11, pg. 283-4].

John Nagy Lec 2.6: Evidence for Evolution 13/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Look at the front limbs—Hand or flipper?

John Nagy Lec 2.6: Evidence for Evolution 14/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Compare to modern northern right whale

John Nagy Lec 2.6: Evidence for Evolution 15/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Body plans for different functions are the same

John Nagy Lec 2.6: Evidence for Evolution 16/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline What is this?

John Nagy Lec 2.6: Evidence for Evolution 17/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Basilosaurs—whales with feet

“The hind limbs of basilosaurids retain. . . the , [patella], , fibula, tarsals, metatarsals, and phalanges. However, [they] are greatly reduced in size and the is not attached to the , making the hind limbs unsuitable to support the body weight of these whales” [11, pg. 284] (Image from [2]).

John Nagy Lec 2.6: Evidence for Evolution 18/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Modern whales have hind limb bones, but no legs

Definition: Vestigial trait A body part that is imperfectly formed and unable to function properly is called vestigial.

John Nagy Lec 2.6: Evidence for Evolution 19/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline What kind of creature is this?

John Nagy Lec 2.6: Evidence for Evolution 20/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline It’s one of these

Pantropical spotted dolphin (Stenella attenuata) mother and baby. What happened to the hind limbs in the ? Note that in the Cargegie State 17 embryo, hind limb buds are regressing. Hind limbs are vestigial.

John Nagy Lec 2.6: Evidence for Evolution 21/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline

In addition to gills and hind limbs, embryonic dolphins develop whiskers like a cat’s. These are all examples of vestigial traits. Image from [11, pg. 273].

John Nagy Lec 2.6: Evidence for Evolution 22/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Lay the fossils out in time

Lay the species out in chronological based on the earliest known fossils of each type. When we do, we see the following patterns: All are connected by a synapomorphic trait: involucrums on their auditory bullae. They appear to be a single lineage changing through time: The hind limbs are becoming detached from the spine and reduced (vestigial). The auditory bullae are becoming more detached from the skull. They are becoming more aquatic.

John Nagy Lec 2.6: Evidence for Evolution 23/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline Transitional fossils

If this hypothesis of change through time were true, we should find transitional fossils. And we do.

Pakicetus: Hooves, involucrum, other cetacean characteristics [1]. : Involucrum, other cetacean characteristics, strongly attached auditory bullae, attached pelvis [3]. : Cetacean characteristics, attached pelvis (probably) [4]. Peregocetus: Cetacean characteristics, attached pelvis [7]. : Cetacean characteristics, detached pelvis [5].

John Nagy Lec 2.6: Evidence for Evolution 24/36 Fossils Examples Genetics Refs Synapomorphies Body plan Vestiges Timeline A more accurate view: Indohyus did not become , etc. Rather, ancestries back to common ancestors, as depicted by the chart. This phylogeny represents evolutionary relationships. Each connection is a node. Nodes represent ancestors. Therefore, at least 17 species are represented: the 9 named + 8 nodes. Groups are defined by synapomorphies (red). Example: Indohyus is more closely related to baleen whales (Mysticetes) that to hippos.

John Nagy Lec 2.6: Evidence for Evolution 25/36 Fossils Examples Genetics Refs Mammals Avians Tetrapods These patterns are common: Mammals

Fossils show transition of reptiles to mammals: Bottom: Early synapsids called pelycosaurs have reptile (laid eggs, jaw attached to back of skull), some mammal-like, characteristics. Middle: Later synapsids, called cynodonts, are more mammal-like (maybe hair, and milk) but retain some reptilian characteristics (laid eggs). Top: Even later synapsids become modern mammals (have hair and feed young with milk, jaw attachment underneath skull).

John Nagy Lec 2.6: Evidence for Evolution 26/36 Fossils Examples Genetics Refs Mammals Avians Tetrapods Another

This is a fossil dinosaur called Microraptor [8]. Long, bony tail and teeth, unlike birds. Feathers over its body, with long feathers for gliding on arms and legs. Chemical traces in the fossil suggest black, slightly irridescent feathers like modern black birds.

John Nagy Lec 2.6: Evidence for Evolution 27/36 Fossils Examples Genetics Refs Mammals Avians Tetrapods These patterns are common: Birds

Birds came from dinosaurs. Many dinosarus with feathers have been discovered, including Velociraptor of Park and Jurassic World fame. Feathers are synapomorphic in one group of dinosaurs. All creatures defined by feathers, including birds, are nested within the dinosaur group; therefore, dinosaurs by definition never went extinct. Unrelated traits—patterns of articulations in the digits, for example—are synapomorphic in precisely the same group.

John Nagy Lec 2.6: Evidence for Evolution 28/36 Fossils Examples Genetics Refs Mammals Avians Tetrapods These patterns are common: Tetrapods

Tetrapods (4-legged creatures) came from fish Early lobe-finned fish (Eusthenopteron): bones in fin similar to tetrapod pattern before any existed on land. Tiktaalik (middle) is a nearly perfect transition between fish and amphibians—it possesses key characteristics of both. First true amphibians arise about 10 million later (Tulerpeton). Note: When did this occur relative to when whales arose?

John Nagy Lec 2.6: Evidence for Evolution 29/36 Fossils Examples Genetics Refs Two hypotheses

If modern cetaceans arose from hoofed mammals like the fossils suggest, then genes of whales and dolphins should be more like those of hoofed mammals than any other mammal type. Genetically, either cetaceans would be a sister group of hoofed mammals (A), or they would be, genetically, hoofed mammals themselves (B).

John Nagy Lec 2.6: Evidence for Evolution 30/36 Fossils Examples Genetics Refs Comparing species genetically

This is a DNA sequence alignment from GNAT3 gene in humans, mice, cows, hippos and a variety of cetaceans [6].

John Nagy Lec 2.6: Evidence for Evolution 31/36 Fossils Examples Genetics Refs Evidence: Whales are genetically hoofed mammals

Evidence from genetic and morpho- logical comparisons [10]. Most analyses place cetaceans alongside hippos genetically. Genetically, hippos (hoofed mammals) are more like whales and dolphins than they are like other hoofed mammals. This analysis [10] corroborates many other studies. This corroborates fossil evidence: Indohyus and Ambulocetus cluster with whales and dolphins. Another group—Mesonychus, an extinct group of hoofed carnivores—may or may not cluster with cetaceans.

John Nagy Lec 2.6: Evidence for Evolution 32/36 Fossils Examples Genetics Refs How did these changes occur?

John Nagy Lec 2.6: Evidence for Evolution 33/36 Fossils Examples Genetics Refs ReferencesI

Philip D. Gingerich, Donald E. Russell, and S. M. Ibrahim Shah. Origin of whales in epicontinential remnand seas: New evidence from the early of Pakistan. Science, 220:403–406, 1983.

Philip D. Gingerich, B. Holly Smith, and Elwyn L. Simons. Hind limbs of Eocene : Evidence of feet in whales. Science, 249:154–157, 1990.

Philip D. Gingerich, Munir ul Haq, Winghart von Koenigswald, William J. Sanders, B. Holly Smith, and Iyad S. Zalmout. New protocetid whale from the middle Eocene of Pakistan: Birth on land, precocial development, and sexual dimorphism. PLoS ONE, 4:e4366, 2009.

Philip D. Gingerich, Munir ul Haq, Iyad S. Zalmout, Intizar Hussain Khan, and M. Sadiq Malkani. Origin of whales from early artiodactyls: Hands and feet of Eocene from Pakistan. Science, 293:2239–2242, 2001.

Richard C. Hulbert, Richard M. Petkewich, Gale A. Bishop, David Bukry, and David P. Aleshire. A new middle eocene protocetid whale (Mammalia: Cetacea: ) and associated biota from Georgia. J. Paleont., 72(5):907–927, 1998.

John Nagy Lec 2.6: Evidence for Evolution 34/36 Fossils Examples Genetics Refs ReferencesII

Takushi Kishida, J. G. M. Thewissen, Takashi Hayakawa, Hiroo Imai, and Kiyokazu Agata. Aquatic adaptation and the evolution of smell and taste in whales. Zool. Lett., 1:9, 2015.

Olivier Lambert, Giovanni Bianucci, Rodolfo Salas-Gismondi, Claudio Di Celma, Etienne Steurbaut, Mario Urbina, and Christian de Muizon. An amphibious whale from the middle Eocene of Peru reveals early South Pacific dispersal of quadrupedal cetaceans. Curr. Biol., 29:1352–1359, 2019.

Quanguo Li, Ke-Qin Gao, Qingjin Meng, Julia A. Clark, Matthew D. Shawkey, Liliana D’Alba, Rui Pei, Mick Ellison, Mark A. Norrell, and Jakob Vinther. Reconstruction of Microraptor and the evolution of iridescent plumage. Science, 335:1215–1219, 2012.

Sirpa Nummela, J. G. M. Thewissen, Sunil Bajpai, Taseer Hussain, and Kishor Kumar. Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing. Anat. Record, 290:716–733, 2007.

Michelle Spaulding, Maureen A. O’Leary, and John Gatesy. Relationships of Cetacea (Artiodactyla) among mammals: Increased taxon sampling alters interpretations of key fossils and character evolution. PLoS ONE, 4(9):e7062, 2009.

John Nagy Lec 2.6: Evidence for Evolution 35/36 Fossils Examples Genetics Refs ReferencesIII

J. G. M. Thewissen, Lisa Noelle Cooper, John C. George, and Sunil Bajpai. From land to water: The origin of whales, dolphins, and porpoises. Evo. Edu. Outreach, 2:272–288, 2009.

J. G. M. Thewissen, S. T. Hussain, and M. Arif. Fossil evidence for the origin of in Archaeocete whales. Science, 263:210–212, 1994.

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