Conceived and designed the experiments: JH. Performed the experiments: JH. Analyzed the data: JLF PDG JH JHH WvK BHS. Wrote the paper: JLF PDG JHH WvK BHS.
The authors have declared that no competing interests exist.
The best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record.
We describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as
A set of extraordinary circumstances produced one of the most complete skeletons of a fossil primate ever recovered, here described as a new genus and species
(A)— Plate A (PMO 214.214) showing holotype skeleton in right lateral view. (B)— Plate B (WDC-MG-210) left side of holotype (reversed for comparison with plate A). Plates show part and counterpart of the same skeleton. Plates have different museum numbers because they are in different museum collections. Note the exceptional completeness of the articulated skeleton in plate A, with left and right hands and the right foot complete, including distal phalanges, and the tail complete to the tip. Stained matrix shows the soft-tissue body outline. Abdomen contains organic remains of food in the digestive tract. All of plate A and parts 1 and 2 on plate B (enclosed in dashed lines) are genuine; remainder of plate B was fabricated during preparation.
Relative positions and museum numbers as in
The new specimen, like some other Messel finds, is complete even to distal phalanges and terminal tail vertebrae. Moreover, it was exceptionally preserved during fossilization, retaining soft tissue outlines and contents of the digestive tract. Like other Messel fossils, however, the skeleton is lightly crushed and must be examined in place. Individual bones and teeth cannot be physically removed to examine individually, a difficulty we have partially overcome with innovative CT imagery.
The specimen is a juvenile, but erupting teeth indicate the developmental age and enable prediction of further growth of the body and limbs. The completeness of the fossil allows us to reconstruct aspects of life history, diet, and locomotion that are difficult to study in fossils. In addition, the skeleton enables identification of characteristics routinely used to distinguish strepsirrhine and haplorhine primates. Our focus here is on morphology and paleobiology, but the skeleton has interest for primate phylogeny as well. The skeleton's features clarify morphologies that have been given critical weight in primate phylogeny, and call into question accepted wisdom about the origin of higher primates.
The first primates of modern aspect appeared at the beginning of the Eocene epoch, about 55 m.y. before present. Two superfamilies can be recognized from the beginning: (1) Tarsioidea, including Eocene Omomyidae and Microchoeridae and living
Messel is a maar lake deposit. The basin in which the deposit accumulated formed during a volcanic explosion. It filled with water, which seemingly, one way or another, accumulated gases that poisoned animals individually, episodically, or periodically
The Messel locality is inferred to represent a paratropical Eocene rain forest. Primates are rare faunal elements at Messel, in spite of the rainforest habitat, and only eight primate specimens are known, all previous finds fragments of partial skeletons (
Present designation | Preserved Parts | Collection | Number and locality | Description |
Complete skeleton, same individual as No. 6b - |
Natural History Museum Oslo PMO 214.214 (found by private collectors in 1982) | This study | ||
Two fragments of a skeleton, same individual as No. 6a - |
WDC-MG -210 (found by private collectors in 1982) | No. |
||
Partial skeleton, comprising skull, thorax, vertebral column, os sacrum, and the right anterior limb | SMF-ME 1228 (found in 1982) | No. |
||
fragmentary mandible with cheek-teeth | SMF-ME 2986 (found in 1997) | No. |
||
Fragment of the pelvis, complete hindlimbs of both sides, and a complete tail vertebral column. | SMNK-Me1125 (found in 1990) | No. |
||
Complete, but dorso-ventrally compressed skull | SMF-ME-3379 (found by private collectors) | No. |
||
Pelvis, baculum, and both hindlimbs | HLMD-Me 7430 (found in 1975) | No. |
||
Right arm, forearm and hand | SMF-ME 1683 (found in 1987) | No. |
||
hindlimbs of both sides and a baculum | SMNK III 1641 (found in 1984) |
In order to comprehend how part and counterpart of the same individual fossil can have such different histories, it is essential to understand how fossils at Messel are collected and preserved. Here complete fossil mammal skeletons are well preserved, along with those of fish, amphibians, reptiles and birds. These almost always lie on bedding planes of the laminated sediment. During the early years of excavation for fossils, between 1971 and 1985, mining for oil shale had extensively exposed sediments. Once mining was finished, plans arose to use the open pit as a garbage dump. With this in mind, early excavations for fossils were necessarily rushed, and less attention was paid to careful bed by bed collecting of fossils. Large blocks of the oil shale were removed and split along bedding planes using long knives. The presence of fossils enhances the splitting.
Before starting preparation of a plate for study, the surface damaged by splitting must be embedded in epoxy or polyester resin. Then the as yet unexposed lateral surface of the plate is prepared to expose the lateral side of the little-damaged fossil. This procedure is necessary as dehydration of the oil shale destroys a fossil. The ideal situation is when part and counterpart are mirror images, and both right and left sides of the animal can be prepared equally well. Alternatively, the split can be such that most bones remain on one plate, leaving their natural cast on the counterpart plate.
From what we know of the present fossil, it was privately collected at Messel in 1983, at the foot of what is known as the Schildkrötenhügel (Turtle Hill) see
Plate B (
Plate A (
The Oslo specimen, plate A, clarifies exactly which parts of plate B were faked, including notably, hands and feet (where some proportions of constructions may have been based on reversed photos of A) and the tail vertebral column. Traces on the surrounding polyester resin background suggest that a cast of the tail of another mammal was inserted into plate B. Additional parts such as the vertebrae between sections 1 and 2 as well the nasal part of the skull on plate B were simply fabricated
The almost complete skeleton on plate A has been well prepared, and it also lies on a polyester resin background. Preservation is unique. The cranium is compressed, but a combination of plates A and B shows virtually the entire dentition. Plate A also shows almost the entire right side of the body and several parts of the left side of the body that are missing on plate B. Only the distal part of the left leg is missing on both plates. Thus the skeleton of
Study of the compressed skeleton was facilitated by X-radiography and microcomputerized tomography (CT):
Contact microradiographs were made with conventional X-ray sources (Faxitron 43804 X-ray cabinet, and Faxitron 43856A X-ray cabinet, Hewlett Packard, USA) on a 25 micron storage screen (SR-HD-IP, Fuji, Japan), combined with a laser scanning digitizer (HD-CR 35 NDT, Duerr-NDT, Germany).
Microradiographs were enlarged by direct projection of the specimen using a microfocus X-ray tube with 10-micron resolution (FXT 100.52, Feinfocus/Yxlon, Germany) on a real-time digital sensor (C7942 CK12, version modified for small bones, Hamamatsu, Japan). Moderately enlarged microradiographs (1.9×) of comparative primate specimens (
CT images were obtained using an industrial Micro CT System (RayScan 200 XE, RayScan Technologies, Germany). The microfocus X-ray tube makes it possible, in principle, to achieve resolutions below 10 microns when small probes a few cm in size are used. However, the principal
(A)—
Mapping of developing teeth was done using ArcGIS. First a high-resolution digital photograph of the dentition visible on the surface of plate A was mapped, tooth by tooth, using good light and a binocular microscope. The high-resolution digital X-ray was geo-referenced using landmarks visible in the photograph and X-ray. This permitted identification of some teeth that were not visible on the surface. Next in sequence a shaded CT image of the same region (
(A)— CT image of the skull in plate A, viewed from the right side. (B)— CT image of the skull in plate A, viewed from the left side. Note the presence of a postorbital bar, parts of the auditory bulla below the acoustic opening, and possible hyoid bones. Tooth homologies are mapped in greater detail in
Measurements of the holotype of
William Jungers (Stony Brook, New York) provided an extensive set of comparative measurements for multivariate analysis of skeletal proportions. Comparisons with the postcranial skeletons of modern primates were made using skeletons in the Senckenberg Museum (Frankfurt):
Comparisons with
Identification of teeth follows conventional nomenclature, with capital letters I, C, P, and M, representing incisors, canines, premolars, and molars. Superscripts indicate upper teeth. Subscripts indicate lower teeth. Deciduous teeth are prefaced with a lowercase d. When distinguished, left and right skeletal elements and teeth are followed by an
Institutional abbreviations: HLMD-Me: Hessisches Landesmuseum Darmstadt, Messel-Collection; PMO: Geological Museum, Natural History Museum, University of Oslo, Norway. SMF-ME: Senckenberg Museum Frankfurt, Messel Collection; SMNK-Me: Staatliches Museum für Naturkunde Karlsruhe, Messel Collection; UMMP: University of Michigan Museum of Paleontology vertebrate collection; UMMZ: University of Michigan Museum of Zoology mammal collection; WDC-MG: Wyoming Dinosaur Center, Messel Grube collection.
Systematic Paleontology
Order Primates Linnaeus, 1758
Suborder Euprimates Hoffstetter, 1977
Family Notharctidae Trouessart, 1879
Subfamily Cercamoniinae Gingerich, 1975
Honoring Charles Darwin on the occasion of his 200th birthday.
By monotypy plate A, (PMO 214.214) with counterpart (plate B WDC-MG-210).
Messel, near Darmstadt (South Hessen, Germany); geographic coordinates are: 49°55′7″ North, 8°45′22″ East.
Messel Formation (middle part of section), early Middle Eocene or early Geiseltalian (MP 11), ca. 47 Ma
M1and M2 display a well developed hypocone but no mesostyle. A metaconule is lacking. The M1 and M2 show a small trigonid and a very broad talonid. In the permanent dentition, P1/P1 have been lost whereas P2/P2 are unicuspid and uniradical, especially reduced in the maxilla. The lower segments of the anterior and posterior limbs are conspicuously short and robust. The phalanges are elongated. A toilet or grooming claw is not present. Molars of
Differs from
Differs from
Differs from
When Franzen described the counterpart specimen (plate B) and assigned it to
The limb proportions of
(
Skeletal element | Measurement (mm) | Remarks |
Cranial length | Total skull length | |
Orbital diameters | Width and height | |
M1 crown | Length and width; measured on CT reconstruction | |
M1 crown | Length, trigonid width, talonid width; measured on CT reconstruction | |
M2 crown | Length, trigonid width, talonid width; measured on CT reconstruction | |
Thorax | Sum of thoracic centrum lengths as articulated | |
Lumbus | Sum of lumbar centrum lengths as articulated | |
Scapula | Maximum length | |
Humerus | Maximum length | |
Radius | Maximum length | |
Hand | Measured from base of wrist to most distal phalanx | |
Ilium | Length measured from center of acetabulum | |
Femur | Maximum length | |
Tibia | Maximum length | |
Foot | Length measured from end of calcaneum to most distal phalanx | |
Vertebral column | Proximal atlas to end of tail | |
Total length with skull | Skull plus vertebral column | |
Head and body length | Without tail |
Based on Micro-CT reconstructions of teeth and x-radiographs of the skeleton.
Nasale: The anterior parts of the nasals are not preserved. The ventral suture with the premaxilla is about one-third of the length of the suture with the maxilla and lachrymal (or median process of maxilla, see below). Following the impressions, the right nasal extends mesially to above I2 whereas the left ends above the border between I1 and I2. The right nasal contains three similar sized slit-like nasal foramina. The most caudal one is situated above the anterior rim of the orbit. The most mesial one occurs above the tip of the deciduous upper canine.
Premaxilla: The suture between the two premaxillae is recognizable between the central incisors. The right premaxilla contains two permanent incisors (
Deciduous dI2 has not yet been shed, and dC1/dC1, dP3/dP3, and dP4/dP4 are still functional. Permanent teeth that are fully erupted include I1/I1, P2/P2, and M1/M1 (P2 is present on plate B [1). Erupting teeth include I2/I2 and M2/M2. Crowns of M3/M3 are fully formed but lack roots. Crowns of P3/P3 and P4/P4 are partially formed, with P4/P4 notably more developed than P3/P3. The crown of C1 appears to be fully formed, while that of C1 is less mineralized. Judging from the stage of crown formation, premolars erupted in the sequence P2/P2 – P4/P4 – P3/P3, as in
Maxilla: The bone forms a large part of the face. It contains the canine, two deciduous premolars, P2 and three molars (
Lachrymal: The lachrymal bone is crushed. There seems to be a substantial facial part, but most of the bone lies within the orbit. The lachrymal foramen is not visible.
Frontal: The frontal bone forms the medial and upper half of the posterior border of the orbit. Mesially, it has a suture with the nasal and lachrymal. There is a well-defined ethmoidal foramen. The processus jugalis is robust and meets the processus frontalis of the jugal halfway. Together the two bones form the postorbital bar.
Jugal: The mesiodorsal beginning of the zygomatic arch as well as the ventral border of the orbit is situated above the metacone of dP4. The zygomatic arch is mesially low and slender. The jugal size increases considerably distally until the divergence of the processus frontalis. Behind this the jugal narrows to about half of its former height. This is also the width of the postorbital bar.
Squamosum: The bone forms the posterior half of the zygomatic arch and ends caudally in the fossa glenoidalis.
Squamosum: Caudally of the rather massive processus postglenoidalis there is a deep porus acusticus, which is not surrounded by an external meatus. The squamosum forms the dorsal roof of the meatus.
Petrosum: The bulla tympanica has completely collapsed. However, the posterior and dorsal part is visible. The bulla of the left side is preserved on plate B, where the dorsal half of the annulus tympanicus is clearly seen on the X-ray photograph
Part of the left parietal and frontal is visible above the well exposed sutura sagittalis. Because of compaction, the skull appears higher than it was originally. A crista sagittalis was not developed. The rather voluminous braincase ends distally at the crista nuchalis. Caudoventrally, the
The following bones form the dorsal and lateral parts of the braincase:
Frontal: As usual, the bone forms the mesial part of the braincase.
Parietal: The bone makes up most of the lateral side of the braincase. It is both deep and wide. Mesially, the parietal meets the frontal bone and caudally it has a long suture with the dorsal part of the occipital. It ends posterolaterally at the nuchal crest.
Occipital: The dorsal extension of the occipital bone (protuberantia occipitalis externa) is wedged between the parietals as a triangular plate.
On the caudal end of the skull, the dorsal rim of the foramen magnum is visible. The atlas is visible to the right of the foramen magnum, pressed against the occipital plane.
The right ramus mandibularis is exposed laterally, with the teeth visible in buccal view. In contrast to adapid skulls
The dentition of
Deciduous teeth: In the mandible, it appears that the central deciduous incisors (dI1) have been shed and replaced. Much smaller second deciduous incisors (dI2) remain in the mandible, on right and left sides. We cannot positively identify any upper deciduous incisors, which may have been shed. Clearly, upper and lower deciduous canines are in place. All four deciduous third and fourth premolars (dP3/dP3 and dP4/dP4) are erupted and in occlusion. All the deciduous teeth have long roots, consistent with circumnatal emergence. At the second premolar position we see only a single tooth generation in the mandible and maxilla, and, after more extensive comparison, conclude that dP2 was probably shed at an early age.
Permanent molars: All three permanent molars can be seen in the dentary. The first permanent molar in the dentary, M1, is fully erupted, occluding in normal position with M1. The long, but open roots of M1 suggest that it was probably erupted for some time (weeks or possibly months). The mandibular second molar, M2, is just erupting, and its roots are less developed. The upper second molar, M2, is displaced but lacks sufficient root development for eruption. Third molars, M3/M3, had no roots mineralized, and these crowns were probably still covered by soft tissues.
Replacement teeth: The first permanent incisor is the most advanced of the replacement teeth; this tooth is fully erupted with root length mineralized perhaps ⅔ or ¾ of final adult length. The tooth labeled I1 is permanent because it is much larger than dI2 and it has a denser crown. Development of I2 is well underway, but it is significantly behind I1.
In the premaxilla, we can see four incisor teeth. The right side is clearest: here, the I1 (with its labial edge slightly broken) is erupted, with a long root (¾ or more mineralized). The more caniniform right I2 shows root development of about ⅔. Radiographs also show a well developed incisor from the left side that is more difficult to identify (it may be I1 or possibly I2; one of these teeth is missing in either case). Maxillary permanent incisors were at or near emergence.
The developing lower canine crown, C1, is substantial, but probably no more than half its eventual size. The massive upper permanent canine crown is probably caught at its maximum width, as mineralization was just outlining flanges at the base of the crown, indicating that a wide but not extremely tall crown was forming. The second premolar is represented by a tiny maxillary tooth, P2, on plate B, and a small mandibular tooth, P2, on both plates A and B. The mandibular tooth has a more densely mineralized crown, casting a denser shadow on radiographs and allying it with other permanent teeth. Root development is long and clearly advanced over that of the remaining permanent premolars. The crown of P4 is less than ½ formed, but noticeably advanced over that of P3; crowns of P4 and P3 can be identified in radiographs, with P4 again much advanced over P3.
Little can be seen of the crowns of the molars in either plate A (
Tooth crowns shown here were extracted digitally to show the entire crown for teeth that are only partially exposed in Plate A (see
The crown of M1 is subrectangular in occlusal outline, with a prominent protocone, paracone, and metacone well spaced on the crown. There is a well-developed hypocone developed on a broad lingual cingulum, but a pericone, if present, was weakly developed (
The crown of M1 is relatively long and narrow (
The crown of M2 is shorter than that of M1, with a broader trigonid and a much broader talonid (
(
Measurements of
The atlas is broken and incomplete. It is attached to the planum nuchale of the cranium. The left wing of the atlas is crushed, whereas the right wing is seen in dorsal view, with a well-developed foramen vertebrale laterale. The lateral surface of the axis is visible in plate A, however the prominent processus spinalis is crushed. C3–C5 are visible in lateral view. Their processus spinales are only partially exposed, whereas their processus transversi are clearly visible. Caudally in the cervical series, the processus transversi become more and more expanded. C6 is crushed, whereas the right scapula covers C7.
By including the first and second thoracic vertebrae, which are hidden below the right scapula, 11 thoracic vertebrae are present although their exact number is difficult to determine and therefore somewhat ambiguous. Whereas T3–T5 are laterally exposed, T6–T8 have rotated around their long axis so that they are seen in dorsal aspect, while T9–T11 are visible laterally. There is no diaphragmatic vertebra, because even the processus spinalis of T11 is slightly but clearly dipping caudally. The ribs are not well preserved. Most of their cartilaginous parts exist only as natural casts. The right humerus mostly covers the sternum.
Caudal to the thoracics are 7 lumbar vertebrae. They are comparatively massive and display cranially oriented transverse processes, which become more and more expanded caudally. No spinal processes are evident on L1–L3, but L4 carries a rather small process slightly dipping caudally. The spinal process of the lumbar vertebrae becomes somewhat larger caudally and dips more in this direction. The os sacrum comprises 3 vertebrae, S1–S3, the most proximal one of which is damaged.
Altogether, there are 31 caudal vertebrae but the last one ends fragmented at a fault. So there may have been one or two more. The 3 most proximal are comparatively short and display strong transverse processes that become weaker more distally in the series. The last transverse process is developed on Ca4, which is already considerably longer and shows only a small processus transversus at its caudal end. All following vertebrae have no processus transversi.
In
(
Photograph (A) and X-ray image (B) show the specimen preserved on plate A (
Photograph (A) and X-ray image (B) show the specimen preserved on plate A (
The right humerus is well exposed in lateral view. Only the distal part of the left humerus can be seen, in medial view. Both are articulated with their respective forelimbs. Proximally, the epiphyseal suture is still present, although nothing can be said about the proximal epiphysis because it is completely obscured by siderite. Here, as elsewhere on the skeleton, siderite formed as a concretion around decomposing cartilage. The crista deltoidea of the humerus is well developed and runs up to the middle of the distal diaphysis. A crista brachiolateralis (crista epicondyli lateralis) is visible distally, and this expands as is seen typically in prosimians. It is not as broad as that of
The trochleae of both humeri are in articulation so no details are visible.
The ulna and radius are completely separated, as is typical for primates. The forearm is unusually short, being about the same length as the humerus. This is the case in
The left ulna has a well developed processus anconaeus, and the incisura semilunaris is deep. The distal end of the left forearm is still articulated with the carpus, whereas that of the right forearm lies on top of the carpus. In both cases, articular facets are not discernible. Of special interest is a substantial excrescence that inflates the distal ends of the right ulna and radius, causing them to be secondarily fused (
The left carpus is proximally exposed from its palmar side. Left metacarpal I is proximally disarticulated, exposing part of the articular facet for articulation with the trapezium. This articulation is clearly saddle-shaped, indicating beyond doubt that the thumb was opposable. The proximal carpals include a transversally oriented pisiform that articulated originally with the ulna proximally and the hamate distally. The rather small lunate articulates proximally with the radius and with the ulna, medially with the scaphoid, and distally with the centrale (
The articulated basal and terminal phalanges of the pollex lie across the distal ends of the radius and ulna. The distal end of the basal phalanx appears to be somewhat deformed, being bent lateropalmarly. It is exposed in lateral aspect. An X-ray (
The terminal phalanx of the pollex, on the lateral side of the ulna, is scutiform in dorsal view. The basal phalanx of the second digit is completely exposed from its medial side, and its distal half covers most of the distal ends of metacarpal II–V. The complete basal phalanx of digit III is seen in medial view. It articulates proximally with metacarpal III, as do metacarpals IV–V with digits IV and V, respectively. Whereas the basal phalanx of digit IV is exposed palmarly, that of digit V is exposed laterally. In a distal direction, the basal phalanges of digits III and V come so closely together that the distal end of the basal phalanx of digit IV is almost completely covered by them. The intermediate phalanges of digits III–V are all exposed in medial view, and digit IV is seen crossing over the diaphysis of the intermediate phalanx of digit V. The terminal phalanx of digit I is exposed from the dorsal side, whereas those of digits II–IV, are seen in palmarolateral view. The terminal phalanx of digit V is exposed between the intermediate phalanges of digits III and IV. All are scutiform, and hence were nail-bearing.
On the right hand, all metacarpals and most phalanges are exposed in dorsal view. Only the phalanges of digit V are turned progressively so that the terminal phalanx is completely exposed in palmar view. The lengths of the basal and middle phalanges of digits II–V are remarkable and resemble those of the modern
All in all, the hand of
(
Photograph (A) and X-ray image (B) show the specimen preserved on plate A (
Photograph (A) and X-ray image (B) show the specimen preserved on plate A (
The proximal part of the left femur is mostly covered by that belonging to the right side, which is laterally exposed. Compared with the caput, the neck of the femur is very short and the trochanter major is very low as in
The left lower limb is missing except for a short proximal fragment beyond the knee joint. Most of the left lower leg is preserved on plate B, although its distal end and the foot are also missing on plate B. Most probably, this part was lost during excavation of the specimen as there are no signs of damage or bite marks on the adjacent bones. The lower leg and foot of the right limb are completely preserved. The tibia is seen in lateral view and the fibula is exposed mainly from its cranial side. Both lie parallel to each other and are not fused. Proximally as well as distally, growth sutures are still visible. The crista tibiae is not well defined, and the proximal end of the tibia is slightly bent caudally as in
The tarsus is exposed in laterocranial view (
Anatomical/morphological characteristic | Lem | Lor | Tar | Ceb | Cer | Hom | ref | Primitive or derived | Interpretation | ||
1 | Moist nose with median cleft in upper lip | X | X | 74: p.24 | Primitive | N/A | — | ||||
2 | Jacobson's vomeronasal organ | X | X | X | X | 74: p.24 | Primitive | N/A | — | ||
3 | Sphenoidal recess in nasal cavity | X | X | 74: p.23 | Primitive | N/A | — | ||||
4 | Reflecting tapetum lucidum in eye | X | X | 74: p.82 | Derived? | N/A | — | ||||
5 | Small brain and braincase | X | X | X | 74: p.82 | Primitive | Present | — | |||
6 | Brain with relatively large olfactory bulbs | X | X | X | 74: p.20 | Primitive | N/A | — | |||
7 | Stapedial/pharyngeal blood supply to brain | X | X | 74: p.22 | Derived? | N/A | — | ||||
8 | Cranium with long rostrum | X | X | 74: p.15 | Primitive | Absent | — | ||||
9 | Shallow mandibular ramus | X | X | 74: p.15 | Primitive | Absent | — | ||||
10 | Open metopic suture between frontal bones | X | X | X | 74: p.15 | Primitive | Present | — | |||
11 | Postorbital bar without postorbital closure | X | X | 74: p.82 | Primitive | Present | — | ||||
12 | Ectotympanic free or in lateral wall | X | X | X | 74: p.28 | Primitive | Present | — | |||
13 | Open mandibular symphysis | X | X | X | 74: p.13 | Primitive | Partial | — | |||
14 | Procumbent to vertical pointed incisors | X | X | X | 74: p.15 | Primitive | Absent | — | |||
15 | Tooth comb of lower incisors-canines | X | X | 74: p.82 | Derived | Absent | — | ||||
16 | Non-dimorphic canine teeth | X | X | X | 87 | Primitive | N/A | — | |||
17 | Upper molars quadrate with hypocone cusp | X | X | X | X | X | 75: p.53 | Derived | Present | Indet. | |
18 | Premolar P4 molarized | X | X | 75: p.53 | Derived? | N/A | — | ||||
19 | Lower molars quadrate w. reduced paraconid | X | X | X | X | X | 75: p.53 | Derived | Present | Indet. | |
20 | Capitate (os magnum) laterally compressed | X | X | 75: P.51 | Derived | N/A | — | ||||
21 | Sloping fibular facet on astragalus or talus | X | X | 74: p.82 | Primitive? | Absent | — | ||||
22 | ‘Tarsi-fulcrumating’ pes with long tarsals | X | X | X | 75: p.40 | Derived | Absent | — | |||
23 | Mediolaterally-compressed mesocuneiform | X | X | 75: p.52 | Derived | Absent | — | ||||
24 | Pes with fourth toe longest | X | X | X | 75: p.40 | Derived | Absent | — | |||
25 | Grooming claw on pedal digit II | X | X | X | 74: p.82 | Primitive | Absent | — | |||
26 | Two or more pairs of mammary glands | X | X | X | 74: p.82 | Primitive | N/A | — | |||
27 | Bicornate uterus | X | X | X | 74: p.83 | Primitive | N/A | — | |||
28 | Epitheliochorial placenta | X | X | 74: p.83 | Primitive | N/A | — | ||||
29 | More precocial (more teeth at birth) | X | X | X | X | 50, 88 | Primitive | N/A | — | ||
30 | Lack of SINE human Alu transpositions | X | X | 89 | Primitive | N/A | — | ||||
1 | Dry nose and continuous upper lip | X | X | X | X | 74: p.24 | Derived | N/A | — | ||
2 | Loss of Jacobson's vomeronasal organ | X | X | 74: p.24 | Derived | N/A | — | ||||
3 | Sphenoidal recess greatly reduced | X | X | X | X | 74: p.23 | Derived | N/A | — | ||
4 | Retinal fovea in eye | X | X | X | X | 74: p.82 | Derived? | N/A | — | ||
5 | Larger brain and braincase | X | X | X | 74: p.82 | Derived | Absent | — | |||
6 | Brain with relatively small olfactory bulbs | X | X | X | 74: p.20 | Derived | N/A | — | |||
7 | Promontory arterial blood supply to brain | X | X | X | X | 74: p.22 | Derived? | N/A | — | ||
8 | Cranium with short rostrum | X | X | X | X | 74: p.15 | Derived | Present | |||
9 | Deep mandibular ramus | X | X | X | X | 74: p.15 | Derived | Present | |||
10 | Fused metopic suture uniting frontals | X | X | X | 74: p.15 | Derived | Absent | — | |||
11 | Partial to complete postorbital closure | X | X | X | X | 74: p.82 | Derived | Absent | — | ||
12 | Ectotympanic in lateral wall or tubular | X | X | X | 74: p.28 | Derived | Absent | — | |||
13 | Fused mandibular symphysis | X | X | X | 74: p.13 | Derived | Partial | ||||
14 | Vertical spatulate incisors | X | X | X | 74: p.82 | Derived | Present | ||||
15 | Interlocking canine teeth | X | X | X | X | 74: p.15 | Primitive | Present | — | ||
16 | Sexually dimorphic canine teeth | X | X | X | 87 | Derived | N/A | — | |||
17 | Upper molars quadrate with hypocone cusp | X | X | X | X | X | 77: p.16 | Derived | Present | Indet. | |
18 | Premolar P4 simple w. transverse pad-mcd crest | X | X | X | 76: p.16 | Derived | N/A | — | |||
19 | Lower molars quadrate w. reduced paraconid | X | X | X | X | X | 76: p.16 | Derived | Present | Indet. | |
20 | Capitate (os magnum) uncompressed | X | X | X | X | 76: p.16 | Primitive | N/A | — | ||
21 | Relatively small, steep fibular facet on astragalus | X | X | X | X | 74: p.82 | Derived | Present | |||
22 | ‘Metatarsi-fulcrumating’ pes w. long metatarsals | X | X | X | 76: p.15 | Primitive | Present | — | |||
23 | Non-compressed mesocuneiform | X | X | X | X | 76: p.15 | Primitive | Present | — | ||
24 | Pes with third toe longest | X | X | X | 76: p.15 | Primitive | Present | — | |||
25 | Loss of all grooming claws | X | X | X | 74: p.82 | Derived | Present | ||||
26 | Single pair of mammary glands | X | X | X | 74: p.82 | Derived | N/A | — | |||
27 | Simplex uterus | X | X | X | 74: p.83 | Derived | N/A | — | |||
28 | Hemochorial placenta | X | X | X | X | 74: p.83 | Derived | N/A | — | ||
29 | Less precocial (fewer teeth at birth) | X | X | 50 | Derived | N/A | — | ||||
30 | SINE human Alu transpositions C7, C9, C12 | X | X | X | X | 89 | Derived | N/A | — |
Abbreviations:
The cuboid, which is situated between the calcaneum proximally and metatarsals IV–V distally, articulates proximomedially with a remarkable high navicular bone. On the lateral side a sesamoid is visible. Seen from the lateral aspect only, it is not possible to decide whether it has a pivot joint with the calcaneum like most primates. The navicular is situated between the talus proximally and the ecto- and mesocuneiform distally. It is a long bone compared to that in lorisines, indriids and anthropoids
By far the strongest of all metatarsals is metatarsal I, as is the entire hallux. Metatarsal I is about twice as thick as metatarsals II–V. As preserved, metatarsal I extends medially almost at right angles to the other metatarsals when viewed dorsally. Proximomedially, part of the articular facet for the entocuneiform can be seen (
All phalanges are exposed mainly from their dorsal side, and all are slightly bent plantarly. Morphologically, the basal and intermediate phalanges do not differ very much from those of the manus, although they are somewhat more robust. This difference in robustness is particularly true for digits I and II of the pes, which are much more robust than their counterparts in the manus. Terminal phalanges IV–V are seen from their dorsal aspects, while III and II are seen progressively but slightly dorsomedially. All terminal phalanges are definitely scutiform, and were therefore nail-bearing, although those of digit II and III appear to be rather narrow. The toilet or grooming claw reported on the second digit of
The presence of a complete skeleton with soft-tissue body contours and contents of the digestive tract brings us close to the paleobiology of the animal's life and death ( the living individual is reconstructed in
To begin, we can see something of the process of death and burial. Shortly after death, it appears that the body sank to the lake bottom, landing on its back before coming to rest on its side. There are no bite marks on the adjacent bones to indicate activity of a predator or scavenger.
A dark shadow surrounds almost the whole skeleton, incomplete only at the tail. This shadow indicates the former outline of body and fur produced as a result of bacterial activity
The neck is straight and arms and legs are slightly angled, lying almost parallel. The hands and feet show a somewhat unusual appearance for skeletons from Messel, with the left palm face up and parallel to the bedding (
Male primates commonly preserve a baculum or penis bone
Sequence of tooth eruption can inform us about other aspects of primate life history. A broad look at tooth formation of
Schultz
Outside of living primates, some very rapidly growing mammals erupt all three molars before replacing any deciduous teeth. The tree shrew for example has the sequence
Eruption of the first permanent molar marks an important transition for primates, that from infant to juvenile
To evaluate
Stage of tooth eruption indicates that when it died
If
Organ systems in
For a check on these projections, we can compare
Thus, with either
There are several ways to try to understand locomotion in primates, and these often involve ratios or indices of pairs of measurements. A favorite is the intermembral index (ratio of humerus+radius length divided by femur+tibia length)
Here we have taken a different approach, compiling measurements of 11 skull, trunk, and limb lengths for 45 species of extant primates, subjecting these to a multivariate principle components analysis (PCA; following
(A)— Bivariate plot of PC-I and PC-II, with both axes drawn to the same scale. All loadings for PC-I are similar and positive, indicating that PC-I represents body size (small primates are at left and larger primates are at right; the coefficient of determination (R2) for PC-I and body weight is greater than 0.8). Loadings for PC-II contrast thorax length and foot length, with climbers having a longer thorax and shorter foot, and leapers having a longer foot and shorter thorax. (B)— Bivariate plot of PC-III and PC-II, with both axes drawn to the same scale. Interpretation of PC-II is the same as in A, but here the scale is expanded. Loadings for PC-III contrast lumbus length and scapula length, with climbers having a longer lumbus and shorter scapula, and leapers having a longer scapula and shorter lumbus.
When
Body weight is an important parameter of life history and functional morphology
Lastly, with a skeleton so complete, we can try something even simpler, matching complete head and body length with a living primate. Based on information in
A body weight of 650–900 g lies above Kay's threshold separating insectivorous primates from those gaining their protein from leaves
The size of the orbit of
The overall shape of the
The bony porus acusticus forms a deep channel in
Living primates have long been divided into Strepsirrhini, with a moist nose and median cleft in the upper lip, and Haplorhini, with a dry nose and continuous upper lip. Strepsirrhini was named by Étienne Geoffroy Saint-Hilaire in 1812
Fossils came into the picture in several ways. Hubrecht
Fossil tarsioid primates including Eocene Omomyidae and Microchoeridae were elevated to haplorhine status from the beginning for the simple reason that
The complete skeleton of
All of the determinate synapomorphies in
As currently conceived, the history of Anthropoidea is traced through the Eocene in somewhat speculatively identified lineages of isolated teeth
We can now document the history of an extraordinary fossil, here named
After comparative study, we conclude that the
Maps showing the provenance of
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Skull of
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Skeletal drawing of
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Right forelimb forelimb of
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Right hind limb of
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Life restorations of
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Cladogram to show systematic position of
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Measurements of individual bones of
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The authors thank the Natural History Museum of the University of Oslo and especially Director Prof. Elen Roaldset for the opportunity to study the specimen. We also thank Prof. Dr. Helmut Heinisch, Dr. Meinolf Hellmund, and Christoph Koehn (Geiseltalmuseum Halle) for a rewarding week comparing the adapiform primates from Geiseltal and for the loan of original primate specimens including the holotype of