CALGARY, CANADA,  August 6, 2008 - Gran Tierra Energy Inc. (AMEX: GTE, TSX: GTE) today announced that the company’s senior management will discuss the company’s results of operations for the second quarter ended June 30, 2008 during a conference call scheduled for Monday, August 11, 2008, at 11:00 a.m. Eastern Time.  The company’s financial results for the second quarter are scheduled to be released earlier that day.

What:                           Gran Tierra Energy Inc.’s Second Quarter Results of Operations Conference Call

When:                           Monday, August 11, 2008, 11:00 a.m. Eastern

Web cast address:         http://www.streetevents.com, http://www.fulldisclosure.com

Dial-in Numbers:           (888) 713-4213 (domestic) or (617) 213-4865 (international),                                                               pass code # 37148965

Contact:                        Al Palombo, Cameron Associates, (212) 245-8800 Ext. 209,

al@cameronassoc.com

Participants may pre-register for the call at:

https://www.theconferencingservice.com/prereg/key.process?key=PFTHEDJUC.

Pre-registrants will be issued a pin number to use when dialing into the live call which will provide quick access to the conference by bypassing the operator upon connection.

If you are unable to participate, an audio replay of the call will be available beginning two hours after the call and will be available until 11:59 p.m. on August 18, 2008, by dialing (888) 286-8010 (domestic) or (617) 801-6888 (international) using confirmation pass code 71727488. An audio replay of the call will also be available on Gran Tierra Energy’s web site, www.grantierra.com, until the next earnings call.

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

CALGARY, Alberta, August 5, 2008, Gran Tierra Energy Inc. (AMEX: GTE; TSX: GTE), a company focused on oil exploration and production in South America, today provided details on it’s exploration and delineation drilling programs, and infrastructure development taking place in Colombia and Argentina.

COLOMBIA

Chaza Block: Costayaco Field

Costayaco-5 Drilling and Testing

Gran Tierra Energy completed drilling of Costayaco-5 on July 27, 2008 when total measured depth of 8,703 feet was reached in basement.  The well was successfully cased on July 31, 2008.  The company encountered good oil shows in cuttings in the Kg Sand Unit of the Rumiyaco Formation, the U Sandstone Unit of the Villeta Formation, the T Sandstone Unit of the Villeta Formation and the Upper Caballos Formation.

Electric logs, cuttings and shows indicate excellent reservoir with fair to good oil saturations in the primary Villeta T reservoir, with thicknesses comparable to previous wells in the field.  No definitive oil-water contact is apparent in the Villeta T reservoirs, but testing will be required to confirm whether water is present in certain intervals.  The Upper Caballos reservoirs also appear to have good oil saturations and thicknesses comparable to previous wells drilled in the field.  The Lower Caballos reservoirs are well developed, but appear to be water bearing.  The top of the Villeta T and Caballos were encountered at a shallower depth than expected and oil shows were encountered deeper than expected in both the Villeta T and the Upper Caballos reservoirs; both results have the potential to add significant reserves to the west flank of the field.  Testing operations are expected to commence in mid-August and will take approximately one month to complete.

The recently reported Costayaco mid-year reserve update did not incorporate potential oil at the Costayaco-5 location as this well was drilled outside the control provided by previously drilled Costayaco wells.  The report indicated that effective July 1, 2008, the Costayaco field had gross proved reserves of 20.5 million barrels of oil, gross proved plus probable reserves of 34.9 million barrels of oil and gross proved plus probable plus possible reserves of 61.4 million barrels of oil.  If hydrocarbon testing is successful, these new reserves will be incorporated in Gran Tierra Energy’s year-end 2008 reserve report.

Costayaco-4 Testing

Gran Tierra Energy is expected to commence testing of Costayaco-4 in early August, 2008; delayed due to the extended testing at Palmera-1 by the test rig.  Log interpretations from data acquired after drilling indicate potential hydrocarbon pay in the Kg Sand Unit of the Rumiyaco Formation, in addition to 14 feet in the U Sandstone Unit of the Villeta Formation, 38 feet in the T Sandstone Unit of the Villeta Formation and 125 feet in the Caballos Formation.  This is almost 25% more potential net pay than in any of the previous three wells in the field.  Gran Tierra Energy expects this testing program to take approximately one month.

Additional Drilling

The drilling of Costayaco-6 and initiating of drilling of Costayaco-7 remain on the program for 2008, with a continuous delineation and development drilling campaign in the Costayaco field continuing through 2009.  The details of the 2009 program will be finalized in the fourth quarter of 2008.

Infrastructure

An 8 inch, 10 kilometer pipeline from the Costayaco field to the Uchupayaco Station on the existing pipeline system was completed on July 29, 2008 and is currently being tested.  This new pipeline will have a capacity of approximately 25,000 barrels of oil per day.  Initial throughput will be approximately 8,500 barrels of oil per day due to facility constraints further downstream in the existing pipeline system.  The company is developing options to increase production utilizing trucks to by-pass infrastructure constraints and expects gross Costayaco field production to rise to approximately 13,000 - 15,000 barrels of oil per day by year-end 2008, with additional production capacity behind pipe.

The Costayaco field is located in the Chaza Block in the Putumayo Basin, where the company has a 50% working interest and is the operator, with Solana Resources holding the remaining 50% working interest.

Azar Block: Palmera-1 Tests First Oil

Gran Tierra Energy initiated re-entry operations of the Palmera-1 well in May 2008, an exploration well drilled in 1996 that had potential oil pay in the Kg Sandstone of the Rumiyaco Formation indicated on logs but was never tested.  Drill stem testing operations were conducted in June and July after a liner was set and perforated from 7,876 to 7,878 feet measured depth in the Kg Sandstone.

Stabilized natural flow of 13-15 degree API oil at a rate of approximately 47 barrels of oil per day with no water was obtained.  The reservoir and oil appear to be similar to the producing Miraflor field in the adjacent Santana Block operated by Gran Tierra Energy.  The well has been completed with a production string and will be shut-in for two months to evaluate optimum artificial lift systems and production facilities.  The company expects initial production rates from the well to be in the range of 150 bopd to 250 bopd gross with artificial lift, with early production to be transported by truck.

Gran Tierra Energy is operator of the Azar Block and has an 80% working interest. Under the terms of a farm-in agreement, Lewis Energy will earn a 50% share of the company’s interest by paying 100% of Gran Tierra Energy’s costs associated with the first three exploration periods, including the Palmera-1 workover and drilling of one exploration well. The Azar Block is subject to the Agencia Nacional de Hidrocarburos (ANH) contract terms, with attractive fiscal terms including a sliding scale royalty commencing at 8% and no back-in rights by the state company Ecopetrol.

Rio Magdalena Block: Popa-2 Testing Operations Continuing

Gran Tierra Energy initiated drill-stem testing operations of the Popa-2 exploration well in the Rio Magdalena Block in the Middle Magdalena Basin, on July 4, 2008. The company encountered oil and gas shows during drilling in the Cretaceous Monserrate Formation, the primary reservoir target in the Popa prospect, and in the underlying basement.  Four drill-stem tests have been completed and three additional drill-stem tests have been added.  Results of the testing are expected in late August.

Gran Tierra Energy, with a 100% working interest, is the operator of the 144,670 acre Rio Magdalena Block.  Under the terms of a recently completed farm-in agreement, Omega Energy Colombia will earn a 60% share of the company’s interest by paying 100% of the costs associated with drilling, testing and completing the Popa-2 well.  In the event of a commercial discovery, Ecopetrol S.A. has a right to back in for a 30% working interest, to be split proportionally between Gran Tierra Energy and Omega Energy Colombia.

ARGENTINA

Surubí Block - Proa.x-1 Exploration Well

Gran Tierra Energy began drilling the Proa.x-1 exploration well on July 9, 2008.  The well is planned to be drilled to a depth of 12,992 feet to test the Cretaceous Palmar Largo reservoir section, which is productive in the Palmar Largo field approximately 2 miles to the northeast in the adjacent Palmar Largo Block.  The company expects drilling to be completed in late August.

In addition, Gran Tierra Energy obtained provincial ratification of a new contract for the 90,688 gross acre Surubi Block with the Formosa Province on July 29, 2008.  This new contract includes a 10-year contract extension to August 15, 2026.  As part of this revised agreement, Gran Tierra Energy has assigned a 15% working interest to REFSA (Recursos Energéticos Formosa S.A.), the provincial government company, while retaining an 85% working interest and operatorship. REFSA will be carried by Gran Tierra Energy during drilling of the Proa.x-1 well. In the event of success, Gran Tierra Energy will be reimbursed for all of the costs incurred during drilling from 50% of the net production assigned to REFSA. The provincial royalties payable on production in the revised contract vary from 12% for cumulative production below 750,000 cubic meters of oil (approximately 4.7 million barrels), to 14% for cumulative production between 750,000 to 1,500,000 cubic meters of oil (approximately 9.4 million barrels), and to 16% for cumulative production above 1,500,000 cubic meters of oil.

SUMMARY

Commenting on the drilling and testing progress, Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc., stated, “These are outstanding preliminary results from Costayaco-5.  Successful testing of oil from this well has the potential to significantly add to the total reserve potential of the Costayaco field, which has already grown significantly in size as delineation drilling has shown in the first half of 2008.  With our first produced oil on the nearby Azar Block, and the promising testing taking place in the Rio Magdalena Block, and exploration drilling continuing in Argentina, the third quarter of this year is proving to be particularly exciting for Gran Tierra Energy.”

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

Cautionary Statement:

Possible reserves are those additional reserves that are less certain to be recovered than probable reserves.  There is a 10% probability that the quantities actually recovered will equal or exceed the sum of proved plus probable plus possible reserves. The estimate of reserves for individual properties may not reflect the same confidence level as estimates of reserves for all properties, due to the effects of aggregation.

Forward Looking Statements:

The statements in this news release regarding Gran Tierra Energy’s plans and expectations for reserves, production, drilling, testing and infrastructure, including the timing of commencement and completion of these events, are forward looking information, forward looking statements or financial outlooks (collectively, “forward-looking statements”)  under the meaning of applicable securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995.  These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements.  Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct. Important factors that could cause the results or outcomes discussed herein to differ materially from those indicated by these forward-looking statements include, among other things:  Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to guerilla activity, technical difficulties and operational difficulties which impact the production, transport or sale of oil and gas; and unexpected problems due to technical difficulties, operational difficulties, and weather conditions.  Further information on potential factors that could affect Gran Tierra Energy are included in risks detailed from time to time in Gran Tierra Energy’s Securities and Exchange Commission filings, including, without limitation, under the caption “Item 1A - Risk Factors” in Part II of Gran Tierra Energy’s Quarterly Report on Form 10-Q for the period ended March 31, 2008, filed with the Securities and Exchange Commission on May 12, 2008.  These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov. The forward-looking statements contained herein are made as at the date of this press release. Subject to its obligations under applicable law, Gran Tierra Energy does not undertake an obligation to update forward-looking or other statements in this release. Gran Tierra Energy’s forward-looking statements are expressly qualified in their entirety by this cautionary statement.

CALGARY, Alberta, July 29, 2008, Gran Tierra Energy Inc. (AMEX:GTE; TSX: GTE) and Solana Resources Limited (TSX-V: SOR; AIM: SORL) announced today that they have entered into a definitive agreement providing for the business combination of Gran Tierra Energy Inc. and Solana Resources Limited.  The transaction is expected to create an exploration and production company with a significantly increased operating scale and balance sheet.

Mr. Dana Coffield, President and Chief Executive Officer of Gran Tierra, will continue as the President and Chief Executive Officer of the combined company, while Mr. J. Scott Price, President and Chief Executive Officer of Solana, will join the board of directors of the combined company.  The board of directors will be comprised of seven members including the current directors of Gran Tierra: Jeffrey Scott, Walter Dawson, Verne Johnson, Nick Kirton, and Dana Coffield, as well as Scott Price, and the current Chairman of the Solana board of directors, Mr. Ray Antony.  Mr. Scott, Chairman of the Gran Tierra board of directors, will maintain his position as Chairman.

Commenting on the transaction Mr. Coffield stated, “We are very pleased to make this announcement and we expect the transaction will create a much more substantial company in a consolidating global industry while preserving Gran Tierra’s operating leadership.  The combination creates a company with a 100 percent working interest in one of the most important oil discoveries in Colombia in recent years, the Costayaco field.  The anticipated production and cash flow growth from Colombia will fund continued exploration on the resulting company’s combined land position, in addition to increasing the capability to undertake much larger and material new venture initiatives in the future.”

Mr. Price stated, “The combination of the two companies will not only consolidate a premium light oil asset in Colombia, but will also launch a substantive, well financed, South American focused entity with an enviable land position and a portfolio of opportunities across the risk spectrum.  We believe this transaction will result in significant value accruing from the asset consolidation and resultant economies of scale.”

Summary of the Transaction

Under the terms of the Agreement, each Solana shareholder will receive either (i) 0.9527918 of a common share of Gran Tierra or; (ii) 0.9527918 of a common share of a Canadian subsidiary of Gran Tierra (an “Exchangeable Share”) for each common share of Solana held, which represents a premium of approximately 14.1 % to the 20 day weighted average trading price to July 28, 2008 of the Solana shares on the TSX Venture Exchange and Gran Tierra’s July 28, 2008, closing price on the Toronto Stock Exchange of CAD $5.73.  The shares of the Canadian subsidiary of Gran Tierra: (i) will have the same voting rights, dividend entitlements and other attributes as Gran Tierra common stock; (ii) will be exchangeable, at each shareholder’s option, on a one-for-one basis, into Gran Tierra common stock; and (iii) subject to compliance with the listing requirements of the Toronto Stock Exchange, will be listed on the Toronto Stock Exchange. The Exchangeable Shares will automatically be exchanged for Gran Tierra common stock five years from closing, and in certain other events.

The transaction will be completed pursuant to a statutory plan of arrangement pursuant to the Business Corporations Act (Alberta).  Upon completion of the transaction, Solana will become an indirect wholly-owned subsidiary of Gran Tierra.  The plan of arrangement will be accomplished on a tax deferred basis in Canada, but may be a taxable transaction for non-Canadian holders of Solana securities.  On a fully diluted basis, upon the closing of the plan of arrangement, Solana securityholders will own approximately 49% of the combined company and Gran Tierra securityholders will own approximately 51% of the combined company.

The proposed transaction is subject to regulatory, stock exchange, court and shareholder approvals.  Gran Tierra and Solana expect to hold shareholder meetings in October 2008.  A joint proxy statement and management information circular is expected to be mailed to shareholders of the companies in September 2008.  The parties have agreed to pay each other a termination fee of $21 million in certain circumstances and an expense reimbursement fee of $1.5 million in certain other circumstances.

Complete details of the plan of arrangement are set out in the agreement, which will be filed by Solana on SEDAR (www.sedar.com) and Gran Tierra on SEDAR and with the Securities and Exchange Commission (www.sec.gov).

Following the offer becoming or being declared unconditional in all respects and as soon as it is able to do so (subject to any applicable requirements of the AIM Rules), Gran Tierra will procure that Solana will apply to the London Stock Exchange for the cancellation of the admission of Solana shares to trading on AIM.  A notice period of not less than 20 business days prior to the cancellation of trading will take effect upon the offer becoming or being declared unconditional in all respects.  Cancellation of admission to trading on AIM is likely to reduce significantly the liquidity and marketability of any Solana shares in respect of which the offer has not been accepted.  Gran Tierra will also seek to have the Solana shares delisted from the TSX Venture Exchange and to cease Solana being a reporting issuer under applicable Canadian securities laws.

Highlights of the Combined Entity

Management of Gran Tierra and Solana expect that the combination will provide many benefits, including the following:

-        Creation of a stronger South American oil producer with significant producing assets in Colombia;

-        Significant exploration portfolio properties in each of Colombia, Argentina and Peru;

-        Consolidation of 100% of the working interest in the Costayaco field (95% economic interest excluding government royalties), a major light oil discovery made in Colombia in 2007, currently under delineation and development;

-        An entity with a pro-forma enterprise value of approximately $1.35 billion based on Gran Tierra’s stock price on July 28, 2008, which is expected to result in enhanced liquidity and a more competitive cost of capital; and

-        Strong pro-forma cash flows which are expected to allow the combined entity to internally finance the exploration and development of the Costayaco field, pursue other exploration opportunities on the combined company’s large undeveloped land base in Colombia, Argentina and Peru, and pursue additional new venture growth opportunities.

Key Pro Forma Operating and Financial Information for the Combined Entity

Some of the key pro forma and financial metrics for the combined company include the following:⁽¹⁾

Mr. Glenn Van Doorne, Chief Operating Officer of Solana, a Petroleum Geologist, and Mr. Dana Coffield, President and CEO of Gran Tierra, a Geologist, are the qualified persons who have reviewed the technical information contained in this news release.

Advisors

Blackmont Capital Inc. is acting as exclusive financial advisor to Gran Tierra with respect to the transaction and has verbally advised the board of directors of Gran Tierra that it is of the opinion, as of the date hereof, that the consideration to be offered by Gran Tierra pursuant to the proposed combination is fair, from a financial point of view, to Gran Tierra shareholders.

Tristone Capital Inc. is acting as exclusive financial advisor to Solana with respect to the transaction and  has verbally advised the board of directors of Solana that it is of the opinion, as of the date hereof, that the consideration to be received by Solana shareholders is fair, from a financial point of view, to Solana shareholders.

Conference Call Information:

Gran Tierra and Solana will hold a joint conference call to review the transaction on Tuesday, July 29, 2008 at 11:00 a.m. Eastern Daylight Time.  The call will be hosted by Mr. Dana Coffield, President and Chief Executive Officer of Gran Tierra, and Mr. Scott Price, President and Chief Executive Officer of Solana Resources. Interested parties may access the conference call by dialing (888) 713-4213 (domestic) or (617) 213-4865 (international), pass code # 95621291.  The call will also be available via web cast at www.grantierra.com, or http://www.streetevents.com, or http://www.fulldisclosure.com

If you are unable to participate, an audio replay of the call will be available beginning two hours after the call and will be available until 11:59 p.m. on August 4, 2008, by dialing (888) 286-8010 (domestic) or (617) 801-6888 (international) using confirmation pass code 74702931.

About Gran Tierra Energy Inc.:

Gran Tierra is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada and is incorporated in the United States. The company holds interests in producing and prospective properties in Colombia, Argentina and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Gran Tierra trades on the American Stock Exchange under the symbol “GTE” and on the Toronto Stock Exchange under the symbol “GTE”.

Additional information concerning Gran Tierra is available at www.grantierra.com, on SEDAR (www.sedar.com) and with the Securities and Exchange Commission (www.sec.gov).

About Solana Resources Limited:

Solana is an international resource company engaged in the acquisition, exploration, development and production of oil and natural gas. The company’s properties are located in Colombia, South America and are held through its wholly owned subsidiary, Solana Petroleum Exploration (Colombia) Limited. The Company is headquartered in Calgary, Alberta, Canada.  Solana trades on the TSX Venture Exchange under the symbol “SOR” and on the AIM Exchange under the symbol “SORL”.

Additional information concerning Solana is available at www.solanaresources.com and on SEDAR (www.sedar.com)

Barrels of Oil Equivalent

Barrels of oil equivalent (boe) is calculated using the conversion factor of 6,000 cubic feet (”6Mcf”) of natural gas being equivalent to one barrel of oil.  Boes may be misleading, particularly if used in isolation.  A boe conversion ratio of 6 Mcf per barrel is based on an energy equivalency conversion method primarily applicable at the burner tip and does not represent a value equivalency at the wellhead.

Forward Looking Statements:

This press release includes “forward-looking statements” within the meaning of the U.S. federal and Canadian securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements are commonly identified by such terms and phrases as “would”, “may”, “will”, “anticipates”, “expects” or “expected to” and other terms with similar meaning indicating possible future events or actions or potential impact on the businesses or shareholders of Gran Tierra Energy Inc. and Solana Resources Limited.  Such statements include, but are not limited to, statements about the anticipated benefits, savings and synergies of the plan of arrangement, including future financial and operating results, the plans, objectives, expectations and intentions of the combined company, the future development of the combined company’s business, and the contingencies and uncertainties to which Gran Tierra and Solana may be subject prior to closing the transaction and other statements that are not historical facts. The press release also includes information that has not been reviewed by the independent auditors of Gran Tierra or Solana. There is no assurance that the proposed transaction contemplated in this press release will be completed at all, or completed upon the same terms and conditions described.

The following factors, among others, could cause actual results to differ materially from those set forth in the forward-looking statements: the ability to obtain required approvals of the plan of arrangement on the proposed terms and schedule; the failure of the shareholders of Solana to approve the plan of arrangement or the shareholders of Gran Tierra to approve the issuance of the Gran Tierra shares to the holders of Solana securities in the proposed transaction; the risk that the businesses will not be integrated successfully; the risk that the cost savings and any revenue synergies from the plan of arrangement may not be fully realized or may take longer to realize than expected; and disruption from the transaction making it more difficult to maintain relationships with regulatory agencies, employees or suppliers.  Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the periodic reports filed by Gran Tierra with the Securities and Exchange Commission and available at the Securities and Exchange Commission’s internet site www.sec.gov and on SEDAR at www.sedar.com, as well as Solana’s continuous disclosure documents filed on Solana’s SEDAR profile at www.sedar.com.

All forward-looking statements in this press release are expressly qualified by information contained in each company’s filings with regulatory authorities and subject to their obligations under applicable securities laws, neither company undertakes to publicly update forward-looking statements, whether as a result of new information, future events or otherwise.

Additional Information

Shareholders are urged to read the joint proxy statement/management information circular regarding the proposed transaction and the registration statement filed on Form S-3 by Gran Tierra when they become available, because they will contain important information. Shareholders will be able to obtain a free copy of the joint proxy statement/management information circular, as well as other filings including the registration statement on Form S-3 containing information about Gran Tierra, without charge, at the Securities and Exchange Commission’s internet site www.sec.gov.  Copies of the joint proxy statement and the filings with the Securities and Exchange Commission that will be incorporated by reference in the joint proxy statement and registration statement on Form S-3 can also be obtained, without charge, by directing a request to Gran Tierra at 1-800-916-4873.

The respective directors and executive officers of Gran Tierra and Solana and other persons may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction.  Information regarding Gran Tierra’s directors and executive officers is available in the 2007 Annual Report on Form 10-K/A filed with the Securities and Exchange Commission by Gran Tierra on May 12, 2008, and information regarding Solana’s directors and executive officers will be included in the joint proxy statement/management information circular.  Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the joint proxy statement and other relevant materials to be filed with the Securities and Exchange Commission when they become available.

No regulatory authority has approved or disapproved the content of this release.  Neither the TSX Venture Exchange nor the Toronto Stock Exchange accepts responsibility for the adequacy or accuracy of this release.

CALGARY, Alberta, July 29, 2008, Gran Tierra Energy Inc. (AMEX: GTE; TSX: GTE), a company focused on oil exploration and production in South America, today announced the results of a mid-year reserve update for the Costayaco Field in the Chaza Block located in the Putumayo Basin of Colombia. Gran Tierra Energy holds a 50% working interest and is the operator of the Costayaco Field and the Chaza Block.  Solana Resources Limited holds the remaining 50% working interest.

An independent reserve evaluation of the Costayaco field conducted by GLJ Petroleum Consultants effective July 1, 2008, using 3-D seismic and drilling results from four wells (Costayaco-1 through -4, not including test results of Costayaco-4 as these test results are not yet available) indicates that the Costayaco field has gross proved reserves of 20.5 million barrels of oil (MMbbl), gross proved plus probable reserves of 34.9 million barrels of oil and gross proved plus probable plus possible reserves of 61.4 million barrels of oil.  The following table summarizes gross reserves for the field, in addition to Gran Tierra Energy’s gross and net reserves:

Gran Tierra Energy’s reserves, net of royalty, compared to year end 2007 for the Costayaco Field as of July 1, 2008 are as follows:

• Proved reserves are 6.67 million barrels of oil compared to 3.27 million barrels of oil at year end 2007, an increase of 104%;
• Probable reserves are 4.32 million barrels of oil compared to 3.32 million barrels of oil at year end 2007, an increase of 30%;
• Possible reserves are 7.91 million barrels of oil compared to 2.60 million barrels of oil at year end 2007, an increase of 204%;
• Total proved, probable and possible, net after royalty, reserves in the Costayaco Field are 18.90 million barrels of oil compared to 9.19 million barrels of oil at year end 2007, an increase of 106%.

Commenting on the reserve update, Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc., stated, “The Costayaco Field in Colombia continues to exceed our expectations.  Drilling in the first half of 2008 has added to our understanding of the reserve potential of the field.  Pending test results from Costayaco-4 and drilling results from Costayaco-5 are expected to add material new information to the reserve potential as we continue to delineate and develop the field with a continuous drilling program through the balance of this year.”

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

Cautionary Statement:

Possible reserves are those additional reserves that are less certain to be recovered than probable reserves.  There is a 10% probability that the quantities actually recovered will equal or exceed the sum of proved plus probable plus possible reserves. The estimate of reserves for individual properties may not reflect the same confidence level as estimates of reserves for all properties, due to the effects of aggregation.

Forward Looking Statements:

The statements in this news release regarding Gran Tierra plans and expectations for testing and drilling, and expectations as to results of these testing and drilling operations, are forward looking information, forward looking statements or financial outlooks (collectively, “forward-looking statements”)  under the meaning of applicable securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995.  These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements.  Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct. Important factors that could cause the results or outcomes discussed herein to differ materially from those indicated by these forward-looking statements, include, among other things:  Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to guerilla activity, technical difficulties and operational difficulties which impact the production, transport or sale of its products, geographic, political and weather conditions; and the usefulness of the information from the test results from Costayaco-4 and drilling results from Costayaco-5 may be different than Gran Tierra Energy predicts.  Further information on potential factors that could affect Gran Tierra Energy are included in risks detailed from time to time in Gran Tierra Energy’s Securities and Exchange Commission filings, including, without limitation, under the caption “Item 1A - Risk Factors” in Part II of Gran Tierra Energy’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 12, 2008.  These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov. The forward-looking statements contained herein are made as at the date of this press release. Gran Tierra Energy does not undertake an obligation to update forward-looking or other statements in this release except as may be required by law. Gran Tierra Energy’s forward-looking statements are expressly qualified in their entirety by this cautionary statement.

CALGARY, Alberta, June 27, 2008, Gran Tierra Energy Inc. (AMEX: GTE; TSX: GTE), a company focused on oil exploration and production in South America, today announced that it had successfully drilled the Popa-2 exploration well in the Rio Magdalena Block in central Colombia, and was preparing to initiate well testing operations.

Gran Tierra Energy initiated drilling of the Popa-2 exploration well in the Rio Magdalena Block in the Middle Magdalena Basin, on May 8, 2008, and reached total measured depth of 8,646 feet in basement on June 21, 2008. Electric logs have been run and preparations are being made to run a 7 inch liner into the wellbore and then initiate drill stem testing operations. Gran Tierra Energy expects testing operations to take approximately two weeks and to be completed by mid-July.

Gran Tierra Energy encountered oil and gas shows during drilling in sandstones in the Cretaceous Monserrate Formation, the primary reservoir target in the Popa prospect, and in the underlying basement. Electric log interpretations together with mudlog and the shows encountered during drilling indicate potential net hydrocarbon pay of approximately 80 feet has been penetrated by the wellbore in the Monserrate Formation.

Popa-2 was drilled 2,035 meters from a non-commercial oil discovery made by Gran Tierra Energy in 2006 at Popa-1, which tested approximately 160 barrels of oil per day. Gran Tierra Energy acquired a new 89 kilometer 2-D seismic program after the initial discovery, and used it to pick the location of Popa-2.

Gran Tierra Energy, with a 100% working interest, is the operator of the 144,670 acre Rio Magdalena Block. Under the terms of a recently completed farm-in agreement, Omega Energy Colombia will earn a 60% share of the company’s interest by paying 100% of the costs associated with drilling, testing and completing the Popa-2 well. In the event of a commercial discovery, Ecopetrol S.A. has a right to back in for a 30% working interest, to be split proportionally between Gran Tierra Energy and Omega Energy Colombia.

Commenting on progress, Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc., stated, “Preliminary results from Popa-2 are very exciting, building on the knowledge acquired from the drilling of Popa-1 and the new 2-D seismic data that we have acquired since then. Testing of Popa-2 will determine the potential of this prospect and, if successful, will confirm a new exploration play on our lands in Colombia.”

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

Forward Looking Statements:

The statements in this news release regarding Gran Tierra Energy’s plans and expectations for testing Popa-2 and results of these testing operations are forward looking information, forward looking statements or financial outlooks (collectively, “forward-looking statements”) under the meaning of applicable securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements. Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct. Important factors that could cause the results or outcomes discussed herein to differ materially from those indicated by these forward-looking statements include, among other things: unexpected problems due to technical difficulties, operational difficulties, guerilla activity, and weather conditions. Further information on potential factors that could affect Gran Tierra Energy are included in risks detailed from time to time in Gran Tierra Energy’s Securities and Exchange Commission filings, including, without limitation, under the caption “Item 1A – Risk Factors” in Part II of Gran Tierra Energy’s Quarterly Report on Form 10-Q for the period ended March 31, 2008, filed with the Securities and Exchange Commission on May 12, 2008. These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov. The forward-looking statements contained herein are made as at the date of this press release. Subject to its obligations under applicable law, Gran Tierra Energy does not undertake an obligation to update forward-looking or other statements in this release. Gran Tierra Energy’s forward-looking statements are expressly qualified in their entirety by this cautionary statement.

CALGARY, Alberta, June 19, 2008, Gran Tierra Energy Inc. (AMEX: GTE; TSX: GTE), a company focused on oil exploration and production in South America, today announced that it is set to join the broad-market Russell 3000 Index when Russell Investments reconstitutes its comprehensive set of U.S. and global equity indexes on June 27, according to a preliminary list of additions posted June 13 on www.russell.com.

Commenting on the matter, Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc. stated, “Inclusion in the Russell 3000 Index reflects the success of our Company. Our oil exploration and development programs have resulted in reserves, production and cash flow growth over the last year and a half, resulting in a material growth in our market capitalization during that period.”

Annual reconstitution of Russell’s U.S. indexes captures the 4,000 largest U.S. stocks as of the end of May, ranking them by total market capitalization. Membership in the Russell 3000, which remains in place for one year, means automatic inclusion in the large-cap Russell 1000 Index or small-cap Russell 2000 Index as well as the appropriate growth and value style indexes. Russell determines membership for its equity indexes primarily by objective, market-capitalization rankings and style attributes.

The Russell 3000 also serves as the U.S. component to the Russell Global Index, which Russell launched last year.
Russell indexes are widely used by investment managers and institutional investors for index funds and as benchmarks for both passive and active investment strategies. An industry-leading $4.4 trillion in assets currently are benchmarked to them. These investment tools originated from Russell’s multi-manager investment business in the early 1980s when the company saw the need for a more objective, market-driven set of benchmarks in order to evaluate outside investment managers.

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

Colombia Operations

Chaza Block

Costayaco-4

Gran Tierra Energy completed drilling operations for Costayaco-4, the fourth well drilled in the Costayaco field, a new oil field discovered in 2007. The Costayaco field is located in the Chaza Block in the Putumayo Basin, where the company has a 50% working interest and is the operator, with Solana Resources holding the remaining 50% working interest.

Gran Tierra Energy drilled Costayaco-4 directionally from the Costayaco-2 well site and drilled through the same reservoir sequences encountered in the previous wells drilled in the field, reaching a total measured depth of 8,884 feet (7,344 feet true vertical depth) on May 24, 2008. The bottom-hole location is approximately 541 meters north of Costayaco-2. Gran Tierra Energy successfully acquired core of the major reservoir intervals in the Villeta T sandstone and the Upper Caballos sandstone. Analysis of the core will provide additional data for reservoir modeling and full field development planning. Log interpretations from data acquired after drilling indicate approximately 16 feet of potential hydrocarbon pay in the Kg Sand Unit of the Rumiyaco Formation, 14 feet in the U Sandstone Unit of the Villeta Formation, 38 feet in the T Sandstone Unit of the Villeta Formation and 125 feet in the Caballos Formation. This is almost 25% more potential net pay than in any of the previous three wells in the field.

Gran Tierra Energy is currently designing a completion and testing program to evaluate the hydrocarbon reservoirs encountered. Gran Tierra Energy expects testing to begin in late June and take approximately one month to complete.

Costayaco-5

Gran Tierra Energy has completed construction of the drilling location for Costayaco-5. The company will drill this well on the west flank of the Costayaco field, approximately 1,120 meters west of Costayaco-2 (1,060 meters north west of Costayaco-1 discovery well) in an attempt to locate the oil-water contact in the T Sandstone Unit and to further define the reserves of the Costayaco Field. Drilling is to commence in late June and finish in late July. The company plans to drill Costayaco-6 and 7 during 2008.

Costayaco Production and Infrastructure

The Costayaco field is currently producing approximately 7,000 barrels of oil per day (bopd) gross from Costayaco-1, -2 and -3, which is being transported by truck to offloading facilities at Uchupayaco on the existing pipeline system. Construction of an 8 inch 10 kilometer oil transfer line from Costayaco-1 to Uchupayaco is approximately 53% complete. Gran Tierra Energy expects the line to be operational in early August. Once connected to existing infrastructure, plans are to ramp up Costayaco production to approximately 10,000 bopd gross, overcoming the Santana to Orito pipeline bottleneck by trucking approximately 3,000 bopd gross around this pipeline segment. Gran Tierra Energy is investigating the opportunity to possibly truck approximately another 3,000 to 5,000 bopd gross north to Neiva. Additional infrastructure expansion is being evaluated to accommodate the anticipated increase in production from the continuing Costayaco drilling program and to negate the need for any trucking.

Rio Magdalena Block

Popa-2 Exploration Well

Gran Tierra Energy initiated drilling of the Popa-2 exploration well in the Rio Magdalena Block in the Middle Magdalena Basin, on May 8, 2008. Gran Tierra Energy expects drilling to be completed in late June. This well is being drilled near a non-commercial oil discovery made by Gran Tierra Energy in 2006 at Popa-1, which tested approximately 160 bopd. Gran Tierra Energy is the operator of the Rio Magdalena Block and has a 100% working interest. Under the terms of a recently completed farm-in agreement, Omega Energy Colombia will earn a 60% share of the company’s interest by paying 100% of the costs associated with the exploration well. In the event of a commercial discovery, Ecopetrol S.A. has a right to back in for a 30% working interest, to be split proportionally between Gran Tierra Energy and Omega Energy Colombia.

Azar Block

Gran Tierra Energy initiated re-entry operations of the Palmera-1 well on May 28, 2008, an exploration well drilled in 1996 that had potential oil pay in the Kg Sandstone of the Rumiyaco Formation indicated on logs but which was never tested. Gran Tierra Energy expects these testing operations to be completed in late June. In addition, the company is continuing to interpret newly acquired 3-D seismic data in preparation for drilling an exploration well in the block. Gran Tierra Energy is operator of the Azar Block and has a 40% working interest.

Peru Operations

Gran Tierra Energy completed the acquisition of approximately 20,000 linear kilometers of new high definition airborne gravity and magnetic data over the entire area of Blocks 122 and 128 in May 2008. Preparations are being made to enter the Second Exploration Periods of both Blocks 122 and 128, beginning with an extensive environmental impact assessment that will be undertaken to support 2-D seismic data that will be acquired in the Second Exploration Period of each block. Block 122 encompasses approximately 1.2 million acres and Block 128 encompasses approximately 2.2 million acres of land. Gran Tierra Energy is operator and holds a 100% working interest in both exploration blocks.

Argentina Operations

Gran Tierra Energy began mobilization of a rig to drill the Proa-1 exploration well in the Surubi Block in the Noroeste Basin of northern Argentina during the second quarter of 2008. The company expects drilling to begin in early July and be completed in late August. Gran Tierra Energy is operator and has a 100% working interest in this block. In addition, technical evaluation work and a variety of well work-overs continue in Gran Tierra Energy’s other six landholdings in the basin.

Production Growth Continues

Gran Tierra Energy’s production for the second quarter to date has averaged approximately 3,250 bopd net after royalty. This is up from an average of 2,842 bopd reported for the first quarter of 2008. Production has grown further to an average of approximately 4,100 bopd net after royalty in early June. The majority of the production growth has taken place in Colombia, with Argentina production having grown to approximately 550 bopd net after royalty.

Commenting on progress, Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc., stated, “The Costayaco Field in Colombia continues to exceed our expectations. Significant progress is being made on defining production infrastructure requirements, advancing production capacity and setting new production targets for the field, in addition to advancing our exploration programs in our other operated blocks in Colombia, Peru and Argentina.”

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).

Forward Looking Statements:

The statements in this news release regarding Gran Tierra Energy’s expected production growth, plans and expectations for testing and drilling, expectations as to results of these testing and drilling operations and infrastructure, the use to which acquired seismic data will be put, the benefits that will result from the identification of the oil-water contact in the Costayaco discovery, and expectations as to completion of the pipeline from Costayaco-1 and the timing for the other events cited above, are forward looking information, forward looking statements or financial outlooks (collectively, “forward-looking statements”) under the meaning of applicable securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements. Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct. Important factors that could cause the results or outcomes discussed herein to differ materially from those indicated by these forward-looking statements, include, among other things: Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to guerilla activity, technical difficulties and operational difficulties which impact the production, transport or sale of its products, and geographic, political and weather conditions; and the usefulness of the seismic data and benefits of the discovery of the oil-water contact may be different than Gran Tierra Energy predicts. Further information on potential factors that could affect Gran Tierra Energy are included in risks detailed from time to time in Gran Tierra Energy’s Securities and Exchange Commission filings, including, without limitation, under the caption “Item 1A – Risk Factors” in Gran Tierra Energy’s Annual Report on Form 10-K/A for the period ended December 31, 2007, filed with the Securities and Exchange Commission on May 12, 2008. These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov. The forward-looking statements contained herein are made as at the date of this press release. Gran Tierra Energy does not undertake an obligation to update forward-looking or other statements in this release. Gran Tierra Energy’s forward-looking statements are expressly qualified in their entirety by this cautionary statement.

CALGARY, CANADA,  May 12, 2008 – Gran Tierra Energy Inc. (AMEX: GTE, TSX: GTE) today announced that the company’s senior management will discuss the company’s results of operations for the first quarter ended March 31, 2008 during a conference call scheduled for Tuesday, May 13, 2008, at 11:00 a.m. Eastern Time.  The company’s financial results for the first quarter are scheduled to be released earlier that day.
What:                  Gran Tierra Energy Inc.’s First Quarter Results of Operations Conference Call
When:                  Tuesday, May 13, 2008, 11:00 a.m. Eastern
Web cast address: http://www.streetevents.com, http://www.fulldisclosure.com
                            
Dial-in Numbers:   (888) 680-0892 (domestic) or (617) 213-4858 (international), pass code # 81399744
Contact:              Al Palombo, Cameron Associates, (212) 245-8800 Ext. 209,  al@cameronassoc.com

Participants may pre-register for the call at:
https://www.theconferencingservice.com/prereg/key.process?key=PQWL684Q4.
Pre-registrants will be issued a pin number to use when dialing into the live call which will provide quick access to the conference by bypassing the operator upon connection.
If you are unable to participate, an audio replay of the call will be available beginning two hours after the call and will be available until 11:59 p.m. on May 20, 2008, by dialing (888) 286-8010 (domestic) or (617) 801-6888 (international) using confirmation pass code 51001211. An audio replay of the call will also be available on Gran Tierra Energy’s web site, www.grantierra.com, until the next earnings call.

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).